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barchart(n)		     BLT Built-In Commands		   barchart(n)

______________________________________________________________________________

NAME
       barchart -  Bar chart for plotting X-Y coordinate data.

SYNOPSIS
       barchart pathName ?option value?...
_________________________________________________________________

DESCRIPTION
       The  barchart  command creates a bar chart for plotting two-dimensional
       data (X-Y coordinates). A bar chart is a	 graphic  means	 of  comparing
       numbers by displaying bars of lengths proportional to the y-coordinates
       of the points they represented.	The bar chart  has  many  configurable
       components: coordinate axes, elements, legend, grid lines, cross hairs,
       etc.  They allow you to customize the look and feel of the graph.

INTRODUCTION
       The barchart command creates a new window for plotting  two-dimensional
       data  (X-Y coordinates), using bars of various lengths to represent the
       data points.  The bars are drawn in a rectangular area displayed in the
       center  of  the new window.  This is the plotting area.	The coordinate
       axes are drawn in  the  margins	surrounding  the  plotting  area.   By
       default,	 the  legend  is drawn in the right margin.  The title is dis‐
       played in top margin.

       A barchart widget has several configurable components: coordinate axes,
       data elements, legend, grid, cross hairs, pens, postscript, and annota‐
       tion markers.  Each component can be queried or modified.

       axis

		 Up to four coordinate axes (two X-coordinate and two  Y-coor‐
		 dinate axes) can be displayed, but you can create and use any
		 number of axes. Axes control what region of data is displayed
		 and  how  the	data is scaled. Each axis consists of the axis
		 line, title, major and minor ticks,  and  tick	 labels.  Tick
		 labels display the value at each major tick.

       crosshairs
		 Cross	hairs  are used to position the mouse pointer relative
		 to the X and Y	 coordinate  axes.  Two	 perpendicular	lines,
		 intersecting  at  the	current	 location of the mouse, extend
		 across the plotting area to the coordinate axes.

       element	 An element represents a set of data to be plotted.   It  con‐
		 tains	an  x  and  y  vector  of values representing the data
		 points.  Each data point is displayed	as  a  bar  where  the
		 length	 of the bar is proportional to the ordinate (Y-coordi‐
		 nate) of the data point.  The appearance of the bar, such  as
		 its color, stipple, or relief is configurable.

		 A  special  case exists when two or more data points have the
		 same abscissa (X-coordinate).	By default, the bars are over‐
		 layed,	 one  on  top of the other.  The bars are drawn in the
		 order of the element display list.  But you can also  config‐
		 ure  the bars to be displayed in two other ways.  They may be
		 displayed as a stack, where each bar (with the same abscissa)
		 is  stacked  on  the previous.	 Or they can be drawn side-by-
		 side as thin bars.  The width of each bar is  a  function  of
		 the number of data points with the same abscissa.

       grid	 Extends the major and minor ticks of the X-axis and/or Y-axis
		 across the plotting area.

       legend	 The legend displays the name and symbol of each data element.
		 The  legend  can  be  drawn  in any margin or in the plotting
		 area.

       marker	 Markers are used annotate or highlight areas  of  the	graph.
		 For  example, you could use a text marker to label a particu‐
		 lar data point. Markers come in various forms: text  strings,
		 bitmaps, connected line segments, images, polygons, or embed‐
		 ded widgets.

       pen	 Pens define attributes for elements.  Data elements use  pens
		 to  specify how they should be drawn.	A data element may use
		 many pens at once.  Here the particular pen used for  a  data
		 point	is  determined	from each element's weight vector (see
		 the element's -weight and -style options).

       postscript
		 The widget can generate encapsulated PostScript output.  This
		 component has several options to configure how the PostScript
		 is generated.

SYNTAX
       barchart pathName ?option value?...  The barchart command creates a new
       window  pathName and makes it into a barchart widget.  At the time this
       command is invoked, there must not exist a window named	pathName,  but
       pathName's  parent  must exist.	Additional options may be specified on
       the command line or in the option database to configure aspects of  the
       graph  such  as its colors and font.  See the configure operation below
       for the exact details about what option and value pairs are valid.

       If successful, barchart returns the path name of the widget.   It  also
       creates	a  new Tcl command by the same name.  You can use this command
       to invoke various operations that query or modify the graph.  The  gen‐
       eral form is: pathName operation ?arg?...  Both operation and its argu‐
       ments determine the exact behavior  of  the  command.   The  operations
       available  for  the graph are described in the BARCHART OPERATIONS sec‐
       tion.

       The command can also be used to access components of the graph.	 path‐
       Name component operation ?arg?...  The operation, now located after the
       name of the component, is the function to be performed on  that	compo‐
       nent. Each component has its own set of operations that manipulate that
       component.  They will be described below in their own sections.

EXAMPLE
       The barchart command creates a new bar chart.

	      # Create a new bar chart.	 Plotting area is black.
	      barchart .b -plotbackground black

       A new Tcl command .b is created.	 This command can be used to query and
       modify the bar chart.  For example, to change the title of the graph to
       "My Plot", you use the new command and the configure operation.

	      # Change the title.
	      .b configure -title "My Plot"

       To add data elements, you use the command and the element component.

	      # Create a new element named "e1"
	      .b element create e1 \
		-xdata { 1 2 3 4 5 6 7 8 9 10 } \
		-ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14
		   155.85 166.60 175.38 }

       The element's X-Y coordinates are specified  using  lists  of  numbers.
       Alternately, BLT vectors could be used to hold the X-Y coordinates.

	      # Create two vectors and add them to the barchart.
	      vector xVector yVector
	      xVector set { 1 2 3 4 5 6 7 8 9 10 }
	      yVector set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
		166.60 175.38 }
	      n.b element create e1 -xdata xVector -ydata yVector

       The  advantage  of using vectors is that when you modify one, the graph
       is automatically redrawn to reflect the new values.

	      # Change the y coordinate of the first point.
	      set yVector(0) 25.18

       An element named e1 is now created in .b.  It is automatically added to
       the display list of elements.  You can use this list to control in what
       order elements are displayed.  To query or reset	 the  element  display
       list, you use the element's show operation.

	      # Get the current display list
	      set elemList [.b element show]
	      # Remove the first element so it won't be displayed.
	      .b element show [lrange $elemList 0 end]

       The  element will be displayed by as many bars as there are data points
       (in this case there are ten).  The bars will be drawn centered  at  the
       x-coordinate  of	 the  data  point.   All  the  bars will have the same
       attributes (colors, stipple, etc).  The width of each bar is by default
       one unit.  You can change this with using the -barwidth option.

	      # Change the scale of the x-coordinate data
	      xVector set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
	      # Make sure we change the bar width too.
	      .b configure -barwidth 0.2

       The  height  of each bar is proportional to the ordinate (Y-coordinate)
       of the data point.

       If two or more data points have the same abscissa (X-coordinate value),
       the  bars  representing those data points may be drawn in various ways.
       The default is to overlay the bars, one	on  top	 of  the  other.   The
       ordering	 is  determined	 from  the  of	element	 display list.	If the
       stacked mode is selected (using the -barmode configuration option), the
       bars are stacked, each bar above the previous.

	      # Display the elements as stacked.
	      .b configure -barmode stacked

       If the aligned mode is selected, the bars having the same x-coordinates
       are displayed side by side.  The width of each bar is a fraction of its
       normal width, based upon the number of bars with the same x-coordinate.

	      # Display the elements side-by-side.
	      .b configure -barmode aligned

       By default, the element's label in the legend will be also e1.  You can
       change the label, or specify no legend entry, again using the element's
       configure operation.

	      # Don't display "e1" in the legend.
	      .b element configure e1 -label ""

       You  can	 configure more than just the element's label.	An element has
       many attributes such as	stipple,  foreground  and  background  colors,
       relief, etc.

	      .b element configure e1 -fg red -bg pink \
		-stipple gray50

       Four  coordinate axes are automatically created: x, x2, y, and y2.  And
       by default, elements are mapped onto the axes x and  y.	 This  can  be
       changed with the -mapx and -mapy options.

	      # Map "e1" on the alternate y axis "y2".
	      .b element configure e1 -mapy y2

       Axes  can  be configured in many ways too.  For example, you change the
       scale of the Y-axis from linear to log using the axis component.

	      # Y-axis is log scale.
	      .b axis configure y -logscale yes

       One important way axes are used is to zoom  in  on  a  particular  data
       region.	Zooming is done by simply specifying new axis limits using the
       -min and -max configuration options.

	      .b axis configure x -min 1.0 -max 1.5
	      .b axis configure y -min 12.0 -max 55.15

       To zoom interactively, you link theaxis configure operations with  some
       user  interaction  (such	 as pressing the mouse button), using the bind
       command.	 To convert between screen  and	 graph	coordinates,  use  the
       invtransform operation.

	      # Click the button to set a new minimum
	      bind .b <ButtonPress-1> {
		  %W axis configure x -min [%W axis invtransform x %x]
		  %W axis configure x -min [%W axis invtransform x %y]
	      }

       By default, the limits of the axis are determined from data values.  To
       reset back to the default limits, set the -min and -max options to  the
       empty value.

	      # Reset the axes to autoscale again.
	      .b axis configure x -min {} -max {}
	      .b axis configure y -min {} -max {}

       By  default,  the  legend is drawn in the right margin.	You can change
       this or any legend configuration options using the legend component.

	      # Configure the legend font, color, and relief
	      .b legend configure -position left -relief raised \
		-font fixed -fg blue

       To prevent the legend from being displayed, turn on the -hide option.

	      # Don't display the legend.
	      .b legend configure -hide yes

       The barchart has simple drawing procedures called markers.  They can be
       used  to	 highlight or annotate data in the graph. The types of markers
       available are bitmaps, polygons, lines, or  windows.   Markers  can  be
       used, for example, to mark or brush points.  For example there may be a
       line marker which indicates some low-water value.  Markers are  created
       using the marker operation.

	      # Create a line represent the low water mark at 10.0
	      .b marker create line -name "low_water" \
		-coords { -Inf 10.0 Inf 10.0 } \
		-dashes { 2 4 2 } -fg red -bg blue

       This creates a line marker named low_water.  It will display a horizon‐
       tal line stretching across the plotting area at the y-coordinate	 10.0.
       The coordinates "-Inf" and "Inf" indicate the relative minimum and max‐
       imum of the axis (in this case the x-axis).  By	default,  markers  are
       drawn  last,  on	 top of the bars.  You can change this with the -under
       option.

	      # Draw the marker before elements are drawn.
	      .b marker configure low_water -under yes

       You can add cross hairs or grid lines using  the	 crosshairs  and  grid
       components.

	      # Display both cross hairs and grid lines.
	      .b crosshairs configure -hide no -color red
	      .b grid configure -hide no -dashes { 2 2 }

       Finally, to get hardcopy of the graph, use the postscript component.

	      # Print the bar chart into file "file.ps"
	      .b postscript output file.ps -maxpect yes -decorations no

       This generates a file file.ps containing the encapsulated PostScript of
       the graph.  The option -maxpect says to scale the plot to the  size  of
       the  page.  Turning off the -decorations option denotes that no borders
       or color backgrounds should be drawn (i.e. the background of  the  mar‐
       gins, legend, and plotting area will be white).

SYNTAX
       barchart pathName ?option value?...  The barchart command creates a new
       window pathName and makes it into a barchart widget.  At the time  this
       command	is  invoked, there must not exist a window named pathName, but
       pathName's parent must exist.  Additional options may may be  specified
       on  the	command line or in the option database to configure aspects of
       the bar chart such as its colors and font.  See the configure operation
       below  for  the	exact  details	as  to what option and value pairs are
       valid.

       If successful, barchart returns pathName. It also  creates  a  new  Tcl
       command	pathName.   This  command may be used to invoke various opera‐
       tions to query or modify the bar chart.	It has the general form: path‐
       Name operation ?arg?...	Both operation and its arguments determine the
       exact behavior of the command.  The operations available	 for  the  bar
       chart are described in the following section.

BARCHART OPERATIONS
       pathName bar elemName ?option value?...
	      Creates  a  new  barchart element elemName.  It's an error if an
	      element elemName already exists.	See the	 manual	 for  barchart
	      for details about what option and value pairs are valid.

       pathName cget option
	      Returns  the  current value of the configuration option given by
	      option.  Option may be any option described below for  the  con‐
	      figure operation.

       pathName configure ?option value?...
	      Queries  or modifies the configuration options of the graph.  If
	      option isn't specified, a list describing	 the  current  options
	      for  pathName  is	 returned.   If	 option	 is specified, but not
	      value, then a list describing option is  returned.   If  one  or
	      more  option  and value pairs are specified, then for each pair,
	      the option option is set to value.  The  following  options  are
	      valid.

	      -background color
		     Sets  the background color. This includes the margins and
		     legend, but not the plotting area.

	      -barmode mode
		     Indicates	how  related  bar  elements  will  be	drawn.
		     Related elements have data points with the same abscissas
		     (X-coordinates). Mode indicates how those segments should
		     be	 drawn.	 Mode  can  be	infront,  aligned, overlap, or
		     stacked.  The default mode is infront.

		     infront   Each successive segment is drawn	 in  front  of
			       the previous.

		     stacked   Each  successive	 segment is stacked vertically
			       on top of the previous.

		     aligned   Segments is displayed  aligned  from  right-to-
			       left.

		     overlap   Like aligned but segments slightly overlap each
			       other.

	      -barwidth value
		     Specifies the width of the bars.  This value can be over‐
		     rided  by	the  individual elements using their -barwidth
		     configuration option.  Value is the  width	 in  terms  of
		     graph coordinates.	 The default width is 1.0.

	      -borderwidth pixels
		     Sets  the width of the 3-D border around the outside edge
		     of the widget.  The -relief option determines if the bor‐
		     der is to be drawn.  The default is 2.

	      -bottommargin pixels
		     Specifies	the  size of the margin below the X-coordinate
		     axis.  If pixels is 0, the size of the margin is selected
		     automatically.  The default is 0.

	      -bufferelements boolean
		     Indicates	whether	 an internal pixmap to buffer the dis‐
		     play of data elements should  be  used.   If  boolean  is
		     true,  data  elements  are	 drawn	to an internal pixmap.
		     This option  is  especially  useful  when	the  graph  is
		     redrawn  frequently while the remains data unchanged (for
		     example, moving a marker across the plot).	 See the SPEED
		     TIPS section.  The default is 1.

	      -cursor cursor
		     Specifies	the  widget's  cursor.	 The default cursor is
		     crosshair.

	      -font fontName
		     Specifies the font of the graph  title.  The  default  is
		     *-Helvetica-Bold-R-Normal-*-18-180-*.

	      -halo pixels
		     Specifies	a  maximum distance to consider when searching
		     for the closest data point	 (see  the  element's  closest
		     operation	below).	  Data points further than pixels away
		     are ignored.  The default is 0.5i.

	      -height pixels
		     Specifies the requested height of widget.	The default is
		     4i.

	      -invertxy boolean
		     Indicates	whether the placement X-axis and Y-axis should
		     be inverted.  If boolean is true, the X and  Y  axes  are
		     swapped.  The default is 0.

	      -justify justify
		     Specifies	how  the title should be justified.  This mat‐
		     ters only when the title contains more than one  line  of
		     text.  Justify  must  be  left,  right,  or  center.  The
		     default is center.

	      -leftmargin pixels
		     Sets the size of the margin from the  left	 edge  of  the
		     window  to	 the  Y-coordinate  axis.  If pixels is 0, the
		     size is calculated automatically.	The default is 0.

	      -plotbackground color
		     Specifies the background color of the plotting area.  The
		     default is white.

	      -plotborderwidth pixels
		     Sets  the	width  of  the	3-D border around the plotting
		     area.  The -plotrelief option determines if a  border  is
		     drawn.  The default is 2.

	      -plotpadx pad
		     Sets  the	amount	of padding to be added to the left and
		     right sides of the plotting area.	Pad can be a  list  of
		     one  or  two  screen distances.  If pad has two elements,
		     the left side of the plotting area entry is padded by the
		     first  distance and the right side by the second.	If pad
		     is just one distance, both the left and right  sides  are
		     padded evenly.  The default is 8.

	      -plotpady pad
		     Sets  the	amount	of  padding to be added to the top and
		     bottom of the plotting area.  Pad can be a list of one or
		     two  screen  distances.  If pad has two elements, the top
		     of the plotting area is padded by the first distance  and
		     the  bottom  by the second.  If pad is just one distance,
		     both the top and bottom are padded evenly.	  The  default
		     is 8.

	      -plotrelief relief
		     Specifies	the  3-D effect for the plotting area.	Relief
		     specifies how the interior of the	plotting  area	should
		     appear relative to rest of the graph; for example, raised
		     means the plot should appear to protrude from the	graph,
		     relative  to  the	surface	 of the graph.	The default is
		     sunken.

	      -relief relief
		     Specifies the 3-D effect for the barchart widget.	Relief
		     specifies	how the graph should appear relative to widget
		     it is packed into; for example, raised  means  the	 graph
		     should appear to protrude.	 The default is flat.

	      -rightmargin pixels
		     Sets  the	size  of  margin from the plotting area to the
		     right edge of the window.	 By  default,  the  legend  is
		     drawn  in	this  margin.  If pixels is than 1, the margin
		     size is selected automatically.

	      -takefocus focus
		     Provides information used when moving the focus from win‐
		     dow  to  window  via  keyboard  traversal	(e.g., Tab and
		     Shift-Tab).  If focus is 0, this means that  this	window
		     should  be skipped entirely during keyboard traversal.  1
		     means that the this  window  should  always  receive  the
		     input  focus.   An	 empty	value means that the traversal
		     scripts make the decision whether to focus on the window.
		     The default is "".

	      -tile image
		     Specifies	a  tiled  background for the widget.  If image
		     isn't "", the background is tiled	using  image.	Other‐
		     wise,  the	 normal	 background  color  is	drawn (see the
		     -background option).  Image  must	be  an	image  created
		     using the Tk image command.  The default is "".

	      -title text
		     Sets  the	title to text. If text is "", no title will be
		     displayed.

	      -topmargin pixels
		     Specifies the size of the margin above the x2  axis.   If
		     pixels is 0, the margin size is calculated automatically.

	      -width pixels
		     Specifies the requested width of the widget.  The default
		     is 5i.

       pathName crosshairs operation ?arg?
	      See the CROSSHAIRS COMPONENT section.

       pathName element operation ?arg?...
	      See the ELEMENT COMPONENTS section.

       pathName extents item
	      Returns the size of a particular item in the graph.   Item  must
	      be  either  leftmargin,  rightmargin,  topmargin,	 bottommargin,
	      plotwidth, or plotheight.

       pathName grid operation ?arg?...
	      See the GRID COMPONENT section.

       pathName invtransform winX winY
	      Performs an inverse coordinate  transformation,  mapping	window
	      coordinates back to graph coordinates, using the standard X-axis
	      and Y-axis.  Returns a list of containing the X-Y graph  coordi‐
	      nates.

       pathName inside x y
	      Returns  1  is  the  designated  screen  coordinate (x and y) is
	      inside the plotting area and 0 otherwise.

       pathName legend operation ?arg?...
	      See the LEGEND COMPONENT section.

       pathName line operation arg...
	      The operation is the same as element.

       pathName marker operation ?arg?...
	      See the MARKER COMPONENTS section.

       pathName metafile ?fileName?
	      This operation is for Window platforms only.  Creates a  Windows
	      enhanced	metafile of the barchart.  If present, fileName is the
	      file name of the new metafile.  Otherwise, the metafile is auto‐
	      matically added to the clipboard.

       pathName postscript operation ?arg?...
	      See the POSTSCRIPT COMPONENT section.

       pathName snap photoName
	      Takes  a	snapshot  of  the graph and stores the contents in the
	      photo image photoName.  PhotoName is the	name  of  a  Tk	 photo
	      image that must already exist.

       pathName transform x y
	      Performs	a coordinate transformation, mapping graph coordinates
	      to window coordinates, using the	standard  X-axis  and  Y-axis.
	      Returns a list containing the X-Y screen coordinates.

       pathName xaxis operation ?arg?...

       pathName x2axis operation ?arg?...

       pathName yaxis operation ?arg?...

       pathName y2axis operation ?arg?...
	      See the AXIS COMPONENTS section.

BARCHART COMPONENTS
       A  graph	 is composed of several components: coordinate axes, data ele‐
       ments, legend, grid, cross hairs, postscript, and  annotation  markers.
       Instead	of  one	 big  set of configuration options and operations, the
       graph is partitioned, where each component has  its  own	 configuration
       options and operations that specifically control that aspect or part of
       the graph.

   AXIS COMPONENTS
       Four coordinate axes are automatically created: two  X-coordinate  axes
       (x and x2) and two Y-coordinate axes (y, and y2).  By default, the axis
       x is located in the bottom margin, y in the left margin, x2 in the  top
       margin, and y2 in the right margin.

       An  axis	 consists  of the axis line, title, major and minor ticks, and
       tick labels.  Major ticks are drawn  at	uniform	 intervals  along  the
       axis.  Each tick is labeled with its coordinate value.  Minor ticks are
       drawn at uniform intervals within major ticks.

       The range of the axis controls what region of data  is  plotted.	  Data
       points outside the minimum and maximum limits of the axis are not plot‐
       ted.  By default, the minimum and maximum limits	 are  determined  from
       the data, but you can reset either limit.

       You can create and use several axes. To create an axis, invoke the axis
       component and its create operation.

	      # Create a new axis called "temperature"
	      .b axis create temperature

       You map data elements to an axis using the element's  -mapy  and	 -mapx
       configuration  options.	They specify the coordinate axes an element is
       mapped onto.

	      # Now map the temperature data to this axis.
	      .b element create "temp" -xdata $x -ydata $tempData \
		  -mapy temperature

       While you can have many axes, only four axes can be displayed  simulta‐
       neously.	  They	are drawn in each of the margins surrounding the plot‐
       ting area.  The axes x and y are drawn in the bottom and left  margins.
       The  axes  x2  and y2 are drawn in top and right margins.  Only x and y
       are shown by default. Note that the axes can have different scales.

       To display a different axis, you invoke one  of	the  following	compo‐
       nents:  xaxis, yaxis, x2axis, and y2axis.  The use operation designates
       the axis to be drawn in the corresponding margin: xaxis in the  bottom,
       yaxis in the left, x2axis in the top, and y2axis in the right.

	      # Display the axis temperature in the left margin.
	      .b yaxis use temperature

       You  can	 configure  axes in many ways. The axis scale can be linear or
       logarithmic.  The  values  along	 the  axis  can	 either	 monotonically
       increase	 or decrease.  If you need custom tick labels, you can specify
       a Tcl procedure to format the label any way you wish.  You can  control
       how  ticks are drawn, by changing the major tick interval or the number
       of minor ticks.	You can define non-uniform tick intervals, such as for
       time-series plots.

       pathName axis cget axisName option
	      Returns  the  current  value  of	the option given by option for
	      axisName.	 Option may be any option described below for the axis
	      configure operation.

       pathName axis configure axisName ?axisName?... ?option value?...
	      Queries or modifies the configuration options of axisName.  Sev‐
	      eral axes can be changed.	 If option  isn't  specified,  a  list
	      describing all the current options for axisName is returned.  If
	      option is specified, but	not  value,  then  a  list  describing
	      option  is  returned.  If one or more option and value pairs are
	      specified, then for each pair, the axis option option is set  to
	      value.  The following options are valid for axes.

	      -autorange range
		     Sets the range of values for the axis to range.  The axis
		     limits are automatically reset to display the most recent
		     data points in this range.	 If range is 0.0, the range is
		     determined from the limits of the data.  If -min or  -max
		     are specified, they override this option.	The default is
		     0.0.

	      -color color
		     Sets the color of the axis and tick labels.  The  default
		     is black.

	      -command prefix
		     Specifies a Tcl command to be invoked when formatting the
		     axis tick labels. Prefix is a string containing the  name
		     of	 a Tcl proc and any extra arguments for the procedure.
		     This command is invoked for each major tick on the	 axis.
		     Two additional arguments are passed to the procedure: the
		     pathname of the widget and the current the numeric	 value
		     of	 the  tick.   The procedure returns the formatted tick
		     label.  If "" is returned, no label will appear  next  to
		     the  tick.	 You can get the standard tick labels again by
		     setting prefix to "".  The default is "".

		     Please note that this procedure is invoked while the  bar
		     chart  is redrawn.	 You may query the widget's configura‐
		     tion options.  But do not reset options, because this can
		     have unexpected results.

	      -descending boolean
		     Indicates whether the values along the axis are monotoni‐
		     cally increasing or decreasing.  If boolean is true,  the
		     axis values will be decreasing.  The default is 0.

	      -hide boolean
		     Indicates whether the axis is displayed.

	      -justify justify
		     Specifies	how  the axis title should be justified.  This
		     matters only when the axis title contains more  than  one
		     line  of  text.  Justify  must be left, right, or center.
		     The default is center.

	      -limits formatStr
		     Specifies a printf-like description to format the minimum
		     and maximum limits of the axis.  The limits are displayed
		     at the top/bottom or left/right  sides  of	 the  plotting
		     area.   FormatStr is a list of one or two format descrip‐
		     tions.  If one description is supplied, both the  minimum
		     and  maximum  limits  are	formatted in the same way.  If
		     two, the first designates	the  format  for  the  minimum
		     limit,  the  second  for  the maximum.  If "" is given as
		     either description, then the that limit will not be  dis‐
		     played.  The default is "".

	      -linewidth pixels
		     Sets  the	width of the axis and tick lines.  The default
		     is 1 pixel.

	      -logscale boolean
		     Indicates whether the scale of the axis is logarithmic or
		     linear.   If  boolean  is	true, the axis is logarithmic.
		     The default scale is linear.

	      -loose boolean
		     Indicates whether the limits of the axis should  fit  the
		     data  points  tightly,  at	 the outermost data points, or
		     loosely, at the outer tick intervals.  This  is  relevant
		     only when the axis limit is automatically calculated.  If
		     boolean is true, the axis range is "loose".  The  default
		     is 0.

	      -majorticks majorList
		     Specifies where to display major axis ticks.  You can use
		     this option to display ticks  at  non-uniform  intervals.
		     MajorList	is  a list of axis coordinates designating the
		     location of major ticks.  No minor ticks are  drawn.   If
		     majorList	is  "", major ticks will be automatically com‐
		     puted. The default is "".

	      -max value
		     Sets the maximum  limit  of  axisName.   Any  data	 point
		     greater than value is not displayed.  If value is "", the
		     maximum limit is calculated using the largest data value.
		     The default is "".

	      -min value
		     Sets  the	minimum limit of axisName. Any data point less
		     than value is not displayed.  If value is "", the minimum
		     limit  is	calculated using the smallest data value.  The
		     default is "".

	      -minorticks minorList
		     Specifies where to display minor axis ticks.  You can use
		     this  option to display minor ticks at non-uniform inter‐
		     vals. MinorList is a list of real	values,	 ranging  from
		     0.0  to  1.0,  designating the placement of a minor tick.
		     No minor ticks are drawn if the -majortick option is also
		     set.   If	minorList is "", minor ticks will be automati‐
		     cally computed. The default is "".

	      -rotate theta
		     Specifies the how many degrees to rotate  the  axis  tick
		     labels.  Theta is a real value representing the number of
		     degrees to rotate the tick labels.	 The  default  is  0.0
		     degrees.

	      -shiftby value
		     Specifies	how  much  to automatically shift the range of
		     the axis.	When the new data  exceeds  the	 current  axis
		     maximum, the maximum is increased in increments of value.
		     You can use this option to prevent the axis  limits  from
		     being recomputed at each new time point. If value is 0.0,
		     then no automatic shifting is down. The default is 0.0.

	      -showticks boolean
		     Indicates whether axis ticks should be drawn. If  boolean
		     is	 true,	ticks are drawn.  If false, only the axis line
		     is drawn. The default is 1.

	      -stepsize value
		     Specifies the interval  between  major  axis  ticks.   If
		     value  isn't a valid interval (must be less than the axis
		     range), the request is ignored and the step size is auto‐
		     matically calculated.

	      -subdivisions number
		     Indicates how many minor axis ticks are to be drawn.  For
		     example, if number is two, only one minor tick is	drawn.
		     If	 number	 is  one,  no  minor ticks are displayed.  The
		     default is 2.

	      -tickfont fontName
		     Specifies the font for axis tick labels. The  default  is
		     *-Courier-Bold-R-Normal-*-100-*.

	      -ticklength pixels
		     Sets the length of major and minor ticks (minor ticks are
		     half the length of major ticks). If pixels is  less  than
		     zero, the axis will be inverted with ticks drawn pointing
		     towards the plot.	The default is 0.1i.

	      -title text
		     Sets the title of the axis. If text is "", no axis	 title
		     will be displayed.

	      -titlecolor color
		     Sets the color of the axis title. The default is black.

	      -titlefont fontName
		     Specifies	the font for axis title. The default is *-Hel‐
		     vetica-Bold-R-Normal-*-14-140-*.

	      Axis configuration options may be also be set by the option com‐
	      mand.   The  resource class is Axis.  The resource names are the
	      names of the axes (such as x or x2).

		     option add *Barchart.Axis.Color  blue
		     option add *Barchart.x.LogScale  true
		     option add *Barchart.x2.LogScale false

       pathName axis create axisName ?option value?...
	      Creates a new axis by the name axisName.	No axis	 by  the  same
	      name  can already exist. Option and value are described in above
	      in the axis configure operation.

       pathName axis delete ?axisName?...
	      Deletes the named axes. An axis is not really deleted  until  it
	      is not longer in use, so it's safe to delete axes mapped to ele‐
	      ments.

       pathName axis invtransform axisName value
	      Performs the inverse transformation, changing the screen coordi‐
	      nate  value  to  a graph coordinate, mapping the value mapped to
	      axisName.	 Returns the graph coordinate.

       pathName axis limits axisName
	      Returns a list of the minimum and maximum limits	for  axisName.
	      The order of the list is min max.

       pathName axis names ?pattern?...
	      Returns  a  list	of axes matching zero or more patterns.	 If no
	      pattern argument is give, the names of all axes are returned.

       pathName axis transform axisName value
	      Transforms the coordinate value to a screen coordinate  by  map‐
	      ping the it to axisName.	Returns the transformed screen coordi‐
	      nate.

       Only four axes can be displayed simultaneously.	By default,  they  are
       x,  y, x2, and y2.  You can swap in a different axis with use operation
       of the special axis components: xaxis, x2axis, yaxis, and y2axis.

	      .g create axis temp
	      .g create axis time
	      ...
	      .g xaxis use temp
	      .g yaxis use time

       Only the axes specified for use are displayed on the screen.

       The xaxis, x2axis, yaxis, and y2axis  components	 operate  on  an  axis
       location	 rather than a specific axis like the more general axis compo‐
       nent does.  The xaxis component manages the X-axis located in the  bot‐
       tom  margin  (whatever  axis that happens to be).  Likewise, yaxis uses
       the Y-axis in the left margin, x2axis the top X-axis,  and  y2axis  the
       right Y-axis.

       They  implicitly control the axis that is currently using to that loca‐
       tion.  By default, xaxis uses the x axis, yaxis uses y, x2axis uses x2,
       and  y2axis  uses  y2.	These components can be more convenient to use
       than always determining what axes are current being  displayed  by  the
       graph.

       The  following  operations  are available for axes. They mirror exactly
       the operations of the axis component.  The axis argument must be xaxis,
       x2axis, yaxis, or y2axis.

       pathName axis cget option

       pathName axis configure ?option value?...

       pathName axis invtransform value

       pathName axis limits

       pathName axis transform value

       pathName axis use ?axisName?
	      Designates  the  axis  axisName is to be displayed at this loca‐
	      tion.  AxisName can not be already in use at  another  location.
	      This  command  returns the name of the axis currently using this
	      location.

   CROSSHAIRS COMPONENT
       Cross hairs consist of two intersecting lines  (one  vertical  and  one
       horizontal)  drawn  completely across the plotting area.	 They are used
       to position the mouse in relation to the coordinate axes.  Cross	 hairs
       differ from line markers in that they are implemented using XOR drawing
       primitives.  This means that they can be quickly drawn and erased with‐
       out redrawing the entire widget.

       The following operations are available for cross hairs:

       pathName crosshairs cget option
	      Returns  the  current  value  of	the  cross hairs configuration
	      option given by option.  Option  may  be	any  option  described
	      below for the cross hairs configure operation.

       pathName crosshairs configure ?option value?...
	      Queries  or  modifies  the  configuration	 options  of the cross
	      hairs.  If option isn't specified, a  list  describing  all  the
	      current  options	for the cross hairs is returned.  If option is
	      specified, but not value,	 then  a  list	describing  option  is
	      returned.	  If one or more option and value pairs are specified,
	      then for each pair, the cross hairs  option  option  is  set  to
	      value.  The following options are available for cross hairs.

	      -color color
		     Sets the color of the cross hairs.	 The default is black.

	      -dashes dashList
		     Sets  the	dash  style  of the cross hairs. DashList is a
		     list of up to 11 numbers that alternately	represent  the
		     lengths  of  the dashes and gaps on the cross hair lines.
		     Each number must be between 1 and 255.   If  dashList  is
		     "", the cross hairs will be solid lines.

	      -hide boolean
		     Indicates	whether	 cross	hairs are drawn. If boolean is
		     true, cross hairs are not drawn.  The default is yes.

	      -linewidth pixels
		     Set the width of the cross hair lines.  The default is 1.

	      -position pos
		     Specifies the  screen  position  where  the  cross	 hairs
		     intersect.	 Pos must be in the form "@x,y", where x and y
		     are the window coordinates of the intersection.

	      Cross hairs configuration options may be	also  be  set  by  the
	      option  command.	The resource name and class are crosshairs and
	      Crosshairs respectively.

		     option add *Barchart.Crosshairs.LineWidth 2
		     option add *Barchart.Crosshairs.Color     red

       pathName crosshairs off
	      Turns off the cross hairs.

       pathName crosshairs on
	      Turns on the display of the cross hairs.

       pathName crosshairs toggle
	      Toggles the current state of the cross hairs,  alternately  map‐
	      ping and unmapping the cross hairs.

ELEMENTS
       A  data	element represents a set of data.  It contains x and y vectors
       which are the coordinates of the data points.  Elements	are  displayed
       as  bars where the length of the bar is proportional to the ordinate of
       the data point.	Elements also control the appearance of the data, such
       as the color, stipple, relief, etc.

       When  new  data elements are created, they are automatically added to a
       list of displayed elements.   The display list controls	what  elements
       are drawn and in what order.

       The following operations are available for elements.

       pathName element activate elemName ?index?...
	      Specifies	 the data points of element elemName to be drawn using
	      active foreground and background colors.	ElemName is  the  name
	      of  the  element and index is a number representing the index of
	      the data point. If no indices are present then all  data	points
	      become active.

       pathName element bind tagName ?sequence?	 ?command?
	      Associates  command  with	 tagName  such that whenever the event
	      sequence given by sequence occurs for an element with this  tag,
	      command will be invoked.	The syntax is similar to the bind com‐
	      mand except that it operates on graph elements, rather than wid‐
	      gets. See the bind manual entry for complete details on sequence
	      and the substitutions performed on command before invoking it.

	      If all arguments are specified then a new	 binding  is  created,
	      replacing	 any  existing	binding for the same sequence and tag‐
	      Name.  If the first character of command is + then command  aug‐
	      ments  an existing binding rather than replacing it.  If no com‐
	      mand argument is provided then the command currently  associated
	      with  tagName  and  sequence (it's an error occurs if there's no
	      such binding) is returned.  If both  command  and	 sequence  are
	      missing  then  a list of all the event sequences for which bind‐
	      ings have been defined for tagName.

       pathName element cget elemName option
	      Returns the current value of the	element	 configuration	option
	      given  by	 option.   Option  may be any of the options described
	      below for the element configure operation.

       pathName element closest x y ?option value?... ?elemName?...
	      Finds the data point representing the bar closest to the	window
	      coordinates  x  and  y in the element elemName.  ElemName is the
	      name of an element, which must be displayed.  If no elements are
	      specified, then all displayed elements are searched.  It returns
	      a list containing the name of the closest element, the index  of
	      its closest point, and the graph coordinates of the point. If no
	      data point within the threshold distance can  be	found,	""  is
	      returned.	 The following option-value pairs are available.

	      -halo pixels
		     Specifies a threshold distance where selected data points
		     are ignored.  Pixels is a valid screen distance, such  as
		     2	or  1.2i.   If	this  option  isn't specified, then it
		     defaults to the value of the barchart's -halo option.

       pathName element configure elemName ?elemName... ?option value?...
	      Queries or modifies  the	configuration  options	for  elements.
	      Several  elements	 can  be  modified at the same time. If option
	      isn't specified, a list describing all the current  options  for
	      elemName	is  returned.	If option is specified, but not value,
	      then a list describing the option option is returned.  If one or
	      more  option  and value pairs are specified, then for each pair,
	      the element option  option  is  set  to  value.	The  following
	      options are valid for elements.

	      -activepen penName
		     Specifies	pen to use to draw active element.  If penName
		     is "", no active elements will be drawn.  The default  is
		     activeLine.

	      -bindtags tagList
		     Specifies the binding tags for the element.  TagList is a
		     list of binding tag names.	 The tags and their order will
		     determine	how events for elements.  Each tag in the list
		     matching the current event sequence  will	have  its  Tcl
		     command  executed.	 Implicitly the name of the element is
		     always the first tag in the list.	The default  value  is
		     all.

	      -background color
		     Sets  the	the  color of the border around each bar.  The
		     default is white.

	      -barwidth value
		     Specifies the width  the  bars  drawn  for	 the  element.
		     Value  is	the  width  in	X-coordinates.	If this option
		     isn't specified, the width of each bar is	the  value  of
		     the widget's -barwidth option.

	      -baseline value
		     Specifies the baseline of the bar segments.  This affects
		     how bars are  drawn  since	 bars  are  drawn  from	 their
		     respective	 y-coordinate  the  baseline.  By  default the
		     baseline is 0.0.

	      -borderwidth pixels
		     Sets the border width of the 3-D border drawn around  the
		     outside  of  each	bar.  The -relief option determines if
		     such a border is drawn.  Pixels must be  a	 valid	screen
		     distance like 2 or 0.25i. The default is 2.

	      -data coordList
		     Specifies	the X-Y coordinates of the data.  CoordList is
		     a list of numeric expressions representing the X-Y	 coor‐
		     dinate pairs of each data point.

	      -foreground color
		     Sets the color of the interior of the bars.

	      -hide boolean
		     Indicates	whether the element is displayed.  The default
		     is no.

	      -label text
		     Sets the element's label in the legend.  If text  is  "",
		     the  element  will	 have  no  entry  in  the legend.  The
		     default label is the element's name.

	      -mapx xAxis
		     Selects the X-axis to  map	 the  element's	 X-coordinates
		     onto.  XAxis must be the name of an axis.	The default is
		     x.

	      -mapy yAxis
		     Selects the Y-axis to  map	 the  element's	 Y-coordinates
		     onto.   YAxis must be the name of an axis. The default is
		     y.

	      -relief string
		     Specifies the 3-D effect desired for bars.	 Relief	 indi‐
		     cates  how the interior of the bar should appear relative
		     to the surface of the chart; for  example,	 raised	 means
		     the bar should appear to protrude from the surface of the
		     plotting area.  The default is raised.

	      -stipple bitmap
		     Specifies a stipple pattern with which to draw the	 bars.
		     If	 bitmap	 is "", then the bar is drawn in a solid fash‐
		     ion.

	      -xdata xVector
		     Specifies the x-coordinate vector of the  data.   XVector
		     is	 the name of a BLT vector or a list of numeric expres‐
		     sions.

	      -ydata yVector
		     Specifies the y-coordinate vector of the  data.   YVector
		     is	 the name of a BLT vector or a list of numeric expres‐
		     sions.

	      Element configuration options may also be set by the option com‐
	      mand.   The  resource names  in the option database are prefixed
	      by elem.

		     option add *Barchart.Element.background blue

       pathName element create elemName ?option value?...
	      Creates a new element elemName.  Element names must  be  unique,
	      so  an  element  elemName	 may not already exist.	 If additional
	      arguments are present, they specify any of the  element  options
	      valid for element configure operation.

       pathName element deactivate pattern...
	      Deactivates  all	the  elements  matching pattern for the graph.
	      Elements whose names match any of the patterns given are redrawn
	      using their normal colors.

       pathName element delete ?pattern?...
	      Deletes  all  the elements matching pattern for the graph.  Ele‐
	      ments whose names match any of the patterns given	 are  deleted.
	      The graph will be redrawn without the deleted elements.

       pathName element exists elemName
	      Returns  1  if an element elemName currently exists and 0 other‐
	      wise.

       pathName element names ?pattern?...
	      Returns the elements matching one or more pattern.  If  no  pat‐
	      tern is given, the names of all elements is returned.

       pathName element show ?nameList?
	      Queries  or modifies the element display list.  The element dis‐
	      play list designates the	elements  drawn	 and  in  what	order.
	      NameList is a list of elements to be displayed in the order they
	      are named.  If there is no nameList argument, the	 current  dis‐
	      play list is returned.

       pathName element type elemName
	      Returns  the type of elemName.  If the element is a bar element,
	      the commands returns the	string	"bar",	otherwise  it  returns
	      "line".

   GRID COMPONENT
       Grid  lines extend from the major and minor ticks of each axis horizon‐
       tally or vertically across the plotting area.  The following operations
       are available for grid lines.

       pathName grid cget option
	      Returns  the current value of the grid line configuration option
	      given by option.	Option may be any option described  below  for
	      the grid configure operation.

       pathName grid configure ?option value?...
	      Queries  or  modifies  the configuration options for grid lines.
	      If option isn't specified, a list	 describing  all  the  current
	      grid  options for pathName is returned.  If option is specified,
	      but not value, then a list describing option  is	returned.   If
	      one  or more option and value pairs are specified, then for each
	      pair, the grid line option option is set to value.  The  follow‐
	      ing options are valid for grid lines.

	      -color color
		     Sets the color of the grid lines.	The default is black.

	      -dashes dashList
		     Sets the dash style of the grid lines. DashList is a list
		     of up  to	11  numbers  that  alternately	represent  the
		     lengths  of  the dashes and gaps on the grid lines.  Each
		     number must be between 1 and 255.	If dashList is "", the
		     grid will be solid lines.

	      -hide boolean
		     Indicates whether the grid should be drawn. If boolean is
		     true, grid lines are not shown. The default is yes.

	      -linewidth pixels
		     Sets the width of grid lines.  The default width is 1.

	      -mapx xAxis
		     Specifies the X-axis to display grid lines.   XAxis  must
		     be	 the  name  of	an  axis or "" for no grid lines.  The
		     default is "".

	      -mapy yAxis
		     Specifies the Y-axis to display grid lines.   YAxis  must
		     be	 the  name  of	an  axis or "" for no grid lines.  The
		     default is y.

	      -minor boolean
		     Indicates whether the grid	 lines	should	be  drawn  for
		     minor  ticks.   If boolean is true, the lines will appear
		     at minor tick intervals.  The default is 1.

	      Grid configuration options may also be set by  the  option  com‐
	      mand.   The  resource  name  and class are grid and Grid respec‐
	      tively.

		     option add *Barchart.grid.LineWidth 2
		     option add *Barchart.Grid.Color	 black

       pathName grid off
	      Turns off the display the grid lines.

       pathName grid on
	      Turns on the display the grid lines.

       pathName grid toggle
	      Toggles the display of the grid.

   LEGEND COMPONENT
       The legend displays a list of the data elements.	 Each  entry  consists
       of the element's symbol and label.  The legend can appear in any margin
       (the default location is in the right margin).  It can  also  be	 posi‐
       tioned anywhere within the plotting area.

       The following operations are valid for the legend.

       pathName legend activate pattern...
	      Selects  legend entries to be drawn using the active legend col‐
	      ors and relief.  All entries whose element names	match  pattern
	      are  selected.  To be selected, the element name must match only
	      one pattern.

       pathName legend bind tagName ?sequence?	?command?
	      Associates command with tagName such  that  whenever  the	 event
	      sequence	given  by sequence occurs for a legend entry with this
	      tag, command will be invoked.  Implicitly the element  names  in
	      the  entry  are tags.  The syntax is similar to the bind command
	      except that it operates on legend entries, rather than  widgets.
	      See  the	bind manual entry for complete details on sequence and
	      the substitutions performed on command before invoking it.

	      If all arguments are specified then a new	 binding  is  created,
	      replacing	 any  existing	binding for the same sequence and tag‐
	      Name.  If the first character of command is + then command  aug‐
	      ments  an existing binding rather than replacing it.  If no com‐
	      mand argument is provided then the command currently  associated
	      with  tagName  and  sequence (it's an error occurs if there's no
	      such binding) is returned.  If both  command  and	 sequence  are
	      missing  then  a list of all the event sequences for which bind‐
	      ings have been defined for tagName.

       pathName legend cget option
	      Returns the current value	 of  a	legend	configuration  option.
	      Option may be any option described below in the legend configure
	      operation.

       pathName legend configure ?option value?...
	      Queries or modifies the configuration options  for  the  legend.
	      If  option isn't specified, a list describing the current legend
	      options for pathName is returned.	 If option is  specified,  but
	      not value, then a list describing option is returned.  If one or
	      more option and value pairs are specified, then for  each	 pair,
	      the legend option option is set to value.	 The following options
	      are valid for the legend.

	      -activebackground color
		     Sets the background color for active legend entries.  All
		     legend  entries  marked  active  (see the legend activate
		     operation) are drawn using this background color.

	      -activeborderwidth pixels
		     Sets the width of the 3-D border around the outside  edge
		     of the active legend entries.  The default is 2.

	      -activeforeground color
		     Sets the foreground color for active legend entries.  All
		     legend entries marked as active (see the legend  activate
		     operation) are drawn using this foreground color.

	      -activerelief relief
		     Specifies	the  3-D  effect  desired  for	active	legend
		     entries.  Relief denotes how the interior	of  the	 entry
		     should appear relative to the legend; for example, raised
		     means the entry should appear to protrude from  the  leg‐
		     end,  relative to the surface of the legend.  The default
		     is flat.

	      -anchor anchor
		     Tells how to position the legend relative	to  the	 posi‐
		     tioning  point  for the legend.  This is dependent on the
		     value of the -position option.  The default is center.

		     left or right
				 The anchor describes how to position the leg‐
				 end vertically.

		     top or bottom
				 The anchor describes how to position the leg‐
				 end horizontally.

		     @x,y	 The anchor specifies how to position the leg‐
				 end  relative	to  the positioning point. For
				 example, if anchor is center then the	legend
				 is centered on the point; if anchor is n then
				 the legend will be drawn such	that  the  top
				 center	 point of the rectangular region occu‐
				 pied by the legend will be at the positioning
				 point.

		     plotarea	 The anchor specifies how to position the leg‐
				 end relative to the plotting area. For	 exam‐
				 ple,  if  anchor is center then the legend is
				 centered in the plotting area; if  anchor  is
				 ne  then  the	legend will be drawn such that
				 occupies the upper right corner of the	 plot‐
				 ting area.

	      -background color
		     Sets  the background color of the legend. If color is "",
		     the legend background with be transparent.

	      -bindtags tagList
		     Specifies the binding tags for legend  entries.   TagList
		     is a list of binding tag names.  The tags and their order
		     will determine how events for legend entries.   Each  tag
		     in the list matching the current event sequence will have
		     its Tcl command executed. The default value is all.

	      -borderwidth pixels
		     Sets the width of the 3-D border around the outside  edge
		     of	 the legend (if such border is being drawn; the relief
		     option determines this).  The default is 2 pixels.

	      -font fontName
		     FontName specifies a font to use when drawing the	labels
		     of	 each  element into the legend.	 The default is *-Hel‐
		     vetica-Bold-R-Normal-*-12-120-*.

	      -foreground color
		     Sets the foreground color of the text drawn for the  ele‐
		     ment's label.  The default is black.

	      -hide boolean
		     Indicates	whether	 the  legend  should  be displayed. If
		     boolean is true,  the  legend  will  not  be  draw.   The
		     default is no.

	      -ipadx pad
		     Sets  the	amount	of internal padding to be added to the
		     width of each legend entry.  Pad can be a list of one  or
		     two  screen distances.  If pad has two elements, the left
		     side of the legend entry is padded by the first  distance
		     and  the  right  side  by the second.  If pad is just one
		     distance, both  the  left	and  right  sides  are	padded
		     evenly.  The default is 2.

	      -ipady pad
		     Sets  an  amount  of  internal padding to be added to the
		     height of each legend entry.  Pad can be a list of one or
		     two  screen  distances.  If pad has two elements, the top
		     of the entry is padded by the first distance and the bot‐
		     tom by the second.	 If pad is just one distance, both the
		     top and bottom of	the  entry  are	 padded	 evenly.   The
		     default is 2.

	      -padx pad
		     Sets  the	padding to the left and right exteriors of the
		     legend.  Pad can be a list of  one	 or  two  screen  dis‐
		     tances.   If  pad	has two elements, the left side of the
		     legend is padded by the first distance and the right side
		     by	 the  second.	If pad has just one distance, both the
		     left and right sides are padded evenly.  The  default  is
		     4.

	      -pady pad
		     Sets  the padding above and below the legend.  Pad can be
		     a list of one or two screen distances.  If	 pad  has  two
		     elements,	the  area  above  the  legend is padded by the
		     first distance and the area below by the second.  If  pad
		     is	 just  one distance, both the top and bottom areas are
		     padded evenly.  The default is 0.

	      -position pos
		     Specifies where the legend is drawn. The  -anchor	option
		     also  affects  where the legend is positioned.  If pos is
		     left, left, top, or bottom, the legend is	drawn  in  the
		     specified margin.	If pos is plotarea, then the legend is
		     drawn inside the plotting area at	a  particular  anchor.
		     If	 pos is in the form "@x,y", where x and y are the win‐
		     dow coordinates, the legend is drawn in the plotting area
		     at the specified coordinates.  The default is right.

	      -raised boolean
		     Indicates	whether	 the legend is above or below the data
		     elements.	This matters only if  the  legend  is  in  the
		     plotting  area.   If  boolean is true, the legend will be
		     drawn on top of any elements that	may  overlap  it.  The
		     default is no.

	      -relief relief
		     Specifies	the  3-D effect for the border around the leg‐
		     end.  Relief specifies how the  interior  of  the	legend
		     should  appear  relative  to  the bar chart; for example,
		     raised means the legend should appear  to	protrude  from
		     the  bar chart, relative to the surface of the bar chart.
		     The default is sunken.

	      Legend configuration options may also be set by the option  com‐
	      mand.  The resource name and class are legend and Legend respec‐
	      tively.

		     option add *Barchart.legend.Foreground blue
		     option add *Barchart.Legend.Relief	    raised

       pathName legend deactivate pattern...
	      Selects legend entries to be drawn using the normal legend  col‐
	      ors  and	relief.	 All entries whose element names match pattern
	      are selected.  To be selected, the element name must match  only
	      one pattern.

       pathName legend get pos
	      Returns  the  name  of  the element whose entry is at the screen
	      position pos in the legend.  Pos must be	in  the	 form  "@x,y",
	      where  x and y are window coordinates.  If the given coordinates
	      do not lie over a legend entry, "" is returned.

   PEN COMPONENTS
       Pens define attributes for elements.   Pens  mirror  the	 configuration
       options	of  data  elements  that  pertain to how symbols and lines are
       drawn.  Data elements use pens to determine how they are drawn.	A data
       element may use several pens at once.  In this case, the pen used for a
       particular data point is determined from each element's	weight	vector
       (see the element's -weight and -style options).

       One  pen, called activeBar, is automatically created.  It's used as the
       default	active	pen  for  elements.  So	 you  can  change  the	active
       attributes for all elements by simply reconfiguring this pen.

	      .g pen configure "activeBar" -fg green -bg green4

       You  can	 create	 and use several pens. To create a pen, invoke the pen
       component and its create operation.

	      .g pen create myPen

       You map pens to a data element  using  either  the  element's  -pen  or
       -activepen options.

	      .g element create "e1" -xdata $x -ydata $tempData \
		  -pen myPen

       An element can use several pens at once. This is done by specifying the
       name of the pen in the element's style list (see the -styles option).

	      .g element configure "e1" -styles { myPen 2.0 3.0 }

       This says that any data point with a weight between 2.0 and 3.0	is  to
       be drawn using the pen myPen.  All other points are drawn with the ele‐
       ment's default attributes.

       The following operations are available for pen components.

       pathName pen cget penName option
	      Returns the current value of the option given by option for pen‐
	      Name.  Option may be any option described below for the pen con‐
	      figure operation.

       pathName pen configure penName ?penName... ?option value?...
	      Queries or modifies the configuration options of	penName.  Sev‐
	      eral pens can be modified at once.  If option isn't specified, a
	      list describing the current options for penName is returned.  If
	      option  is  specified,  but  not	value,	then a list describing
	      option is returned.  If one or more option and value  pairs  are
	      specified,  then	for each pair, the pen option option is set to
	      value.  The following options are valid for pens.

	      -background color
		     Sets the the color of the border around  each  bar.   The
		     default is white.

	      -borderwidth pixels
		     Sets  the border width of the 3-D border drawn around the
		     outside of each bar.  The -relief	option	determines  if
		     such  a  border  is drawn.	 Pixels must be a valid screen
		     distance like 2 or 0.25i. The default is 2.

	      -foreground color
		     Sets the color of the interior of the bars.

	      -relief string
		     Specifies the 3-D effect desired for bars.	 Relief	 indi‐
		     cates  how the interior of the bar should appear relative
		     to the surface of the chart; for  example,	 raised	 means
		     the  bar  should  appear  to protrude from the bar chart,
		     relative to  the  surface	of  the	 plotting  area.   The
		     default is raised.

	      -stipple bitmap
		     Specifies	a stipple pattern with which to draw the bars.
		     If bitmap is "", then the bar is drawn in a  solid	 fash‐
		     ion.

	      -type elemType
		     Specifies the type of element the pen is to be used with.
		     This option should only be	 employed  when	 creating  the
		     pen.   This is for those that wish to mix different types
		     of elements (bars and lines)  on  the  same  graph.   The
		     default type is "bar".

	      Pen  configuration options may be also be set by the option com‐
	      mand.  The resource class is Pen.	 The resource  names  are  the
	      names of the pens.

		     option add *Barchart.Pen.Foreground   blue
		     option add *Barchart.activeBar.foreground	green

       pathName pen create penName ?option value?...
	      Creates  a new pen by the name penName.  No pen by the same name
	      can already exist. Option and value are described	 in  above  in
	      the pen configure operation.

       pathName pen delete ?penName?...
	      Deletes  the named pens. A pen is not really deleted until it is
	      not longer in use, so it's safe to delete pens  mapped  to  ele‐
	      ments.

       pathName pen names ?pattern?...
	      Returns  a  list	of pens matching zero or more patterns.	 If no
	      pattern argument is give, the names of all pens are returned.

   POSTSCRIPT COMPONENT
       The barchart can generate encapsulated PostScript  output.   There  are
       several	configuration  options you can specify to control how the plot
       will be generated.  You can change the  page  dimensions	 and  borders.
       The  plot itself can be scaled, centered, or rotated to landscape.  The
       PostScript output can be written directly to a file or returned through
       the interpreter.

       The following postscript operations are available.

       pathName postscript cget option
	      Returns  the  current  value  of	the postscript option given by
	      option.  Option may be any option described below for the	 post‐
	      script configure operation.

       pathName postscript configure ?option value?...
	      Queries  or  modifies  the  configuration options for PostScript
	      generation.  If option isn't specified, a	 list  describing  the
	      current  postscript options for pathName is returned.  If option
	      is specified, but not value, then a list	describing  option  is
	      returned.	  If one or more option and value pairs are specified,
	      then for each pair, the  postscript  option  option  is  set  to
	      value.  The following postscript options are available.

	      -center boolean
		     Indicates	whether	 the  plot  should  be centered on the
		     PostScript page.  If boolean is false, the plot  will  be
		     placed in the upper left corner of the page.  The default
		     is 1.

	      -colormap varName
		     VarName must be the name of a global array variable  that
		     specifies	a color mapping from the X color name to Post‐
		     Script.  Each element of varName must  consist  of	 Post‐
		     Script  code  to set a particular color value (e.g. ``1.0
		     1.0 0.0 setrgbcolor'').  When generating  color  informa‐
		     tion in PostScript, the array variable varName is checked
		     if an element of the name as the color exists. If so,  it
		     uses  its	value  as  the	PostScript  command to set the
		     color.  If this option hasn't been specified, or if there
		     isn't an entry in varName for a given color, then it uses
		     the red, green, and blue intensities from the X color.

	      -colormode mode
		     Specifies how to output color information.	 Mode must  be
		     either  color  (for full color output), gray (convert all
		     colors to their gray-scale equivalents) or mono  (convert
		     foreground	 colors	 to  black  and	 background  colors to
		     white).  The default mode is color.

	      -fontmap varName
		     VarName must be the name of a global array variable  that
		     specifies	a  font	 mapping from the X font name to Post‐
		     Script.  Each element of varName must consist  of	a  Tcl
		     list with one or two elements; the name and point size of
		     a PostScript font.	 When outputting  PostScript  commands
		     for  a  particular	 font,	the  array variable varName is
		     checked to see  if	 an  element  by  the  specified  font
		     exists.   If  there  is  such  an	element, then the font
		     information contained in that  element  is	 used  in  the
		     PostScript	 output.   (If	the point size is omitted from
		     the list, the point size of the X font is used).	Other‐
		     wise  the	X font is examined in an attempt to guess what
		     PostScript font to use.  This works only for fonts	 whose
		     foundry  property	is  Adobe  (such  as Times, Helvetica,
		     Courier, etc.).  If all  of  this	fails  then  the  font
		     defaults to Helvetica-Bold.

	      -decorations boolean
		     Indicates	whether	 PostScript commands to generate color
		     backgrounds and 3-D borders will be output.   If  boolean
		     is	 false, the graph will background will be white and no
		     3-D borders will be generated. The default is 1.

	      -height pixels
		     Sets the height of the plot.  This lets you print the bar
		     chart  with  a height different from the one drawn on the
		     screen.  If pixels is 0, the height is the	 same  as  the
		     widget's height.  The default is 0.

	      -landscape boolean
		     If boolean is true, this specifies the printed area is to
		     be rotated 90 degrees.  In non-rotated output the	X-axis
		     of the printed area runs along the short dimension of the
		     page (``portrait'' orientation); in  rotated  output  the
		     X-axis runs along the long dimension of the page (``land‐
		     scape'' orientation).  Defaults to 0.

	      -maxpect boolean
		     Indicates to scale the plot so that it  fills  the	 Post‐
		     Script  page.   The aspect ratio of the barchart is still
		     retained.	The default is 0.

	      -padx pad
		     Sets the horizontal padding for the left and  right  page
		     borders.	The borders are exterior to the plot.  Pad can
		     be a list of one or two screen distances.	If pad has two
		     elements, the left border is padded by the first distance
		     and the right border by the second.  If pad has just  one
		     distance,	both  the  left	 and  right borders are padded
		     evenly.  The default is 1i.

	      -pady pad
		     Sets the vertical padding for the	top  and  bottom  page
		     borders.  The  borders are exterior to the plot.  Pad can
		     be a list of one or two screen distances.	If pad has two
		     elements,	the top border is padded by the first distance
		     and the bottom border by the second.  If pad has just one
		     distance,	both  the  top	and  bottom borders are padded
		     evenly.  The default is 1i.

	      -paperheight pixels
		     Sets the height of the postscript page.  This can be used
		     to select between different page sizes (letter, A4, etc).
		     The default height is 11.0i.

	      -paperwidth pixels
		     Sets the width of the postscript page.  This can be  used
		     to select between different page sizes (letter, A4, etc).
		     The default width is 8.5i.

	      -width pixels
		     Sets the width of the plot.  This	lets  you  generate  a
		     plot  of  a  width different from that of the widget.  If
		     pixels is 0, the width is the same as the widget's width.
		     The default is 0.

	      Postscript  configuration	 options  may  be  also	 be set by the
	      option command.  The resource name and class are postscript  and
	      Postscript respectively.

		     option add *Barchart.postscript.Decorations false
		     option add *Barchart.Postscript.Landscape	 true

       pathName postscript output ?fileName? ?option value?...
	      Outputs  a file of encapsulated PostScript.  If a fileName argu‐
	      ment isn't present, the command returns the PostScript.  If  any
	      option-value  pairs  are present, they set configuration options
	      controlling how the PostScript is generated.  Option  and	 value
	      can  be  anything accepted by the postscript configure operation
	      above.

   MARKER COMPONENTS
       Markers are simple drawing procedures used  to  annotate	 or  highlight
       areas of the graph.  Markers have various types: text strings, bitmaps,
       images, connected lines, windows, or polygons.  They can be  associated
       with  a	particular  element, so that when the element is hidden or un-
       hidden, so is the marker.  By  default,	markers	 are  the  last	 items
       drawn,  so  that	 data  elements	 will  appear in behind them.  You can
       change this by configuring the -under option.

       Markers, in contrast to elements, don't affect the scaling of the coor‐
       dinate axes.  They can also have elastic coordinates (specified by -Inf
       and Inf respectively) that translate into the minimum or maximum	 limit
       of  the axis.  For example, you can place a marker so it always remains
       in the lower left corner of the plotting area, by using the coordinates
       -Inf,-Inf.

       The following operations are available for markers.

       pathName marker after markerId ?afterId?
	      Changes the order of the markers, drawing the first marker after
	      the second.  If no second afterId	 argument  is  specified,  the
	      marker  is  placed at the end of the display list.  This command
	      can be used to control how markers are displayed	since  markers
	      are drawn in the order of this display list.

       pathName marker before markerId ?beforeId?
	      Changes  the  order  of  the  markers,  drawing the first marker
	      before the second.  If no second beforeId argument is specified,
	      the marker is placed at the beginning of the display list.  This
	      command can be used to control how markers are  displayed	 since
	      markers are drawn in the order of this display list.

       pathName marker bind tagName ?sequence?	?command?
	      Associates  command  with	 tagName  such that whenever the event
	      sequence given by sequence occurs for a marker  with  this  tag,
	      command will be invoked.	The syntax is similar to the bind com‐
	      mand except that it operates on graph markers, rather than  wid‐
	      gets. See the bind manual entry for complete details on sequence
	      and the substitutions performed on command before invoking it.

	      If all arguments are specified then a new	 binding  is  created,
	      replacing	 any  existing	binding for the same sequence and tag‐
	      Name.  If the first character of command is + then command  aug‐
	      ments  an existing binding rather than replacing it.  If no com‐
	      mand argument is provided then the command currently  associated
	      with  tagName  and  sequence (it's an error occurs if there's no
	      such binding) is returned.  If both  command  and	 sequence  are
	      missing  then  a list of all the event sequences for which bind‐
	      ings have been defined for tagName.

       pathName marker cget option
	      Returns the current value of  the	 marker	 configuration	option
	      given  by	 option.   Option may be any option described below in
	      the configure operation.

       pathName marker configure markerId ?option value?...
	      Queries or modifies the configuration options for	 markers.   If
	      option  isn't  specified,	 a list describing the current options
	      for markerId is returned.	  If  option  is  specified,  but  not
	      value,  then  a  list  describing option is returned.  If one or
	      more option and value pairs are specified, then for  each	 pair,
	      the marker option option is set to value.

	      The  following  options are valid for all markers.  Each type of
	      marker  also  has	 its  own  type-specific  options.   They  are
	      described in the sections below.

	      -bindtags tagList
		     Specifies	the binding tags for the marker.  TagList is a
		     list of binding tag names.	 The tags and their order will
		     determine	how  events for markers are handled.  Each tag
		     in the list matching the current event sequence will have
		     its  Tcl  command	executed.   Implicitly the name of the
		     marker is always the first tag in the list.  The  default
		     value is all.

	      -coords coordList
		     Specifies	the coordinates of the marker.	CoordList is a
		     list of graph coordinates.	  The  number  of  coordinates
		     required  is  dependent  on  the  type  of marker.	 Text,
		     image, and window markers need only two  coordinates  (an
		     X-Y  coordinate).	 Bitmap markers can take either two or
		     four coordinates (if four, they represent the corners  of
		     the bitmap). Line markers need at least four coordinates,
		     polygons at least six.  If coordList is  "",  the	marker
		     will not be displayed.  The default is "".

	      -element elemName
		     Links  the	 marker with the element elemName.  The marker
		     is drawn only if the element is also currently  displayed
		     (see  the	element's show operation).  If elemName is "",
		     the marker is always drawn.  The default is "".

	      -hide boolean
		     Indicates whether the marker  is  drawn.  If  boolean  is
		     true, the marker is not drawn.  The default is no.

	      -mapx xAxis
		     Specifies	the  X-axis  to map the marker's X-coordinates
		     onto.  XAxis must the name of an axis.  The default is x.

	      -mapy yAxis
		     Specifies the Y-axis to map  the  marker's	 Y-coordinates
		     onto.  YAxis must the name of an axis.  The default is y.

	      -name markerId
		     Changes  the  identifier  for the marker.	The identifier
		     markerId can not already be used by another  marker.   If
		     this   option  isn't  specified,  the  marker's  name  is
		     uniquely generated.

	      -under boolean
		     Indicates whether the marker is  drawn  below/above  data
		     elements.	 If  boolean  is  true, the marker is be drawn
		     underneath the data elements.  Otherwise, the  marker  is
		     drawn on top of the element.  The default is 0.

	      -xoffset pixels
		     Specifies a screen distance to offset the marker horizon‐
		     tally.  Pixels is a valid screen distance, such as	 2  or
		     1.2i.  The default is 0.

	      -yoffset pixels
		     Specifies	a screen distance to offset the markers verti‐
		     cally.  Pixels is a valid screen distance, such as	 2  or
		     1.2i.  The default is 0.

	      Marker  configuration options may also be set by the option com‐
	      mand.  The resource class is either BitmapMarker,	  ImageMarker,
	      LineMarker,  PolygonMarker, TextMarker, or WindowMarker, depend‐
	      ing on the type of marker.  The resource name is the name of the
	      marker.

		     option add *Barchart.TextMarker.Foreground white
		     option add *Barchart.BitmapMarker.Foreground white
		     option add *Barchart.m1.Background	    blue

       pathName marker create type ?option value?...
	      Creates  a marker of the selected type. Type may be either text,
	      line, bitmap, image, polygon, or window.	This  command  returns
	      the  marker  identifier,	used  as  the markerId argument in the
	      other marker-related commands.  If the  -name  option  is	 used,
	      this  overrides  the normal marker identifier.  If the name pro‐
	      vided is already used for another marker, the  new  marker  will
	      replace the old.

       pathName marker delete ?name?...
	      Removes  one  of	more markers.  The graph will automatically be
	      redrawn without the marker..

       pathName marker exists markerId
	      Returns 1 if the marker markerId exists and 0 otherwise.

       pathName marker names ?pattern?
	      Returns the names of all the markers that currently  exist.   If
	      pattern  is  supplied,  only  those markers whose names match it
	      will be returned.

       pathName marker type markerId
	      Returns the type of the marker given by markerId, such  as  line
	      or  text.	 If markerId is not a valid a marker identifier, "" is
	      returned.

   BITMAP MARKERS
       A bitmap marker displays a bitmap.  The size  of	 the  bitmap  is  con‐
       trolled	by  the	 number of coordinates specified.  If two coordinates,
       they specify the position of the top-left corner of  the	 bitmap.   The
       bitmap  retains	its normal width and height.  If four coordinates, the
       first and second pairs of coordinates represent the corners of the bit‐
       map.   The bitmap will be stretched or reduced as necessary to fit into
       the bounding rectangle.

       Bitmap markers are created with the marker's create  operation  in  the
       form:  pathName	marker	create	bitmap ?option value?...  There may be
       many option-value pairs, each sets  a  configuration  options  for  the
       marker.	 These	same  option-value pairs may be used with the marker's
       configure operation.

       The following options are specific to bitmap markers:

       -background color
	      Same as the -fill option.

       -bitmap bitmap
	      Specifies the bitmap to be displayed.   If  bitmap  is  "",  the
	      marker will not be displayed.  The default is "".

       -fill color
	      Sets  the background color of the bitmap.	 If color is the empty
	      string, no background will be transparent.   The	default	 back‐
	      ground color is "".

       -foreground color
	      Same as the -outline option.

       -mask mask
	      Specifies	 a mask for the bitmap to be displayed. This mask is a
	      bitmap itself, denoting the pixels  that	are  transparent.   If
	      mask is "", all pixels of the bitmap will be drawn.  The default
	      is "".

       -outline color
	      Sets the foreground color of the bitmap. The  default  value  is
	      black.

       -rotate theta
	      Sets  the rotation of the bitmap.	 Theta is a real number repre‐
	      senting the angle of rotation in degrees.	 The marker  is	 first
	      rotated  and  then placed according to its anchor position.  The
	      default rotation is 0.0.

   IMAGE MARKERS
       A image marker displays an image.  Image markers are created  with  the
       marker's	 create	 operation  in	the form: pathName marker create image
       ?option value?...  There may be many option-value pairs,	 each  sets  a
       configuration option for the marker.  These same option-value pairs may
       be used with the marker's configure operation.

       The following options are specific to image markers:

       -anchor anchor
	      Anchor tells how to position the image relative to the position‐
	      ing  point  for the image. For example, if anchor is center then
	      the image is centered on the point;  if anchor  is  n  then  the
	      image  will  be drawn such that the top center point of the rec‐
	      tangular region occupied by the image will be at the positioning
	      point.  This option defaults to center.

       -image image
	      Specifies	 the  image  to	 be drawn.  If image is "", the marker
	      will not be drawn.  The default is "".

   LINE MARKERS
       A line marker displays one or more connected line segments.  Line mark‐
       ers  are	 created  with marker's create operation in the form: pathName
       marker create line ?option value?...  There may	be  many  option-value
       pairs,  each  sets  a  configuration option for the marker.  These same
       option-value pairs may be used with the marker's configure operation.

       The following options are specific to line markers:

       -dashes dashList
	      Sets the dash style of the line. DashList is a list of up to  11
	      numbers that alternately represent the lengths of the dashes and
	      gaps on the line.	 Each number must be between 1	and  255.   If
	      dashList is "", the marker line will be solid.

       -fill color
	      Sets  the background color of the line.  This color is used with
	      striped lines (see the -fdashesoption). If color	is  the	 empty
	      string,  no  background color is drawn (the line will be dashed,
	      not striped).  The default background color is "".

       -linewidth pixels
	      Sets the width of the lines.  The default width is 0.

       -outline color
	      Sets the foreground color of the	line.  The  default  value  is
	      black.

       -stipple bitmap
	      Specifies a stipple pattern used to draw the line, rather than a
	      solid line.  Bitmap specifies a bitmap to	 use  as  the  stipple
	      pattern.	 If  bitmap  is	 "", then the line is drawn in a solid
	      fashion. The default is "".

   POLYGON MARKERS
       A polygon marker displays a closed region described as two or more con‐
       nected line segments.  It is assumed the first and last points are con‐
       nected.	Polygon markers are created using the marker create  operation
       in  the	form:  pathName marker create polygon ?option value?...	 There
       may be many option-value pairs, each sets a  configuration  option  for
       the  marker.  These same option-value pairs may be used with the marker
       configure command to change the marker's configuration.	The  following
       options are supported for polygon markers:

       -dashes dashList
	      Sets the dash style of the outline of the polygon. DashList is a
	      list of up to 11 numbers that alternately represent the  lengths
	      of  the  dashes  and  gaps  on the outline.  Each number must be
	      between 1 and 255. If dashList is "",  the  outline  will	 be  a
	      solid line.

       -fill color
	      Sets  the	 fill  color of the polygon.  If color is "", then the
	      interior of the polygon is transparent.  The default is white.

       -linewidth pixels
	      Sets the width of the outline of the polygon. If pixels is zero,
	      no outline is drawn. The default is 0.

       -outline color
	      Sets the color of the outline of the polygon.  If the polygon is
	      stippled (see the -stipple option),  then	 this  represents  the
	      foreground color of the stipple.	The default is black.

       -stipple bitmap
	      Specifies	 that the polygon should be drawn with a stippled pat‐
	      tern rather than a solid color. Bitmap specifies a bitmap to use
	      as  the  stipple	pattern.  If bitmap is "", then the polygon is
	      filled with a solid color (if the -fill  option  is  set).   The
	      default is "".

   TEXT MARKERS
       A  text	marker displays a string of characters on one or more lines of
       text.  Embedded newlines cause line breaks.  They may be used to	 anno‐
       tate  regions  of  the graph.  Text markers are created with the create
       operation in the form: pathName marker create  text  ?option  value?...
       There  may be many option-value pairs, each sets a configuration option
       for the text marker.  These same option-value pairs may	be  used  with
       the marker's configure operation.

       The following options are specific to text markers:

       -anchor anchor
	      Anchor  tells how to position the text relative to the position‐
	      ing point for the text. For example, if anchor  is  center  then
	      the  text is centered on the point; if anchor is n then the text
	      will be drawn such that the top center point of the  rectangular
	      region  occupied	by  the text will be at the positioning point.
	      This default is center.

       -background color
	      Same as the -fill option.

       -font fontName
	      Specifies the font of the text.	The  default  is  *-Helvetica-
	      Bold-R-Normal-*-120-*.

       -fill color
	      Sets  the	 background  color of the text.	 If color is the empty
	      string, no background will be transparent.   The	default	 back‐
	      ground color is "".

       -foreground color
	      Same as the -outline option.

       -justify justify
	      Specifies	 how  the text should be justified.  This matters only
	      when the marker contains more than one  line  of	text.  Justify
	      must be left, right, or center.  The default is center.

       -outline color
	      Sets the color of the text. The default value is black.

       -padx pad
	      Sets  the	 padding  to the left and right exteriors of the text.
	      Pad can be a list of one or two screen distances.	  If  pad  has
	      two  elements,  the left side of the text is padded by the first
	      distance and the right side by the second.  If pad has just  one
	      distance,	 both the left and right sides are padded evenly.  The
	      default is 4.

       -pady pad
	      Sets the padding above and below the text.  Pad can be a list of
	      one  or two screen distances.  If pad has two elements, the area
	      above the text is padded by the  first  distance	and  the  area
	      below  by the second.  If pad is just one distance, both the top
	      and bottom areas are padded evenly.  The default is 4.

       -rotate theta
	      Specifies the number of degrees to rotate the text.  Theta is  a
	      real  number  representing the angle of rotation.	 The marker is
	      first rotated along its center and is then  drawn	 according  to
	      its anchor position. The default is 0.0.

       -text text
	      Specifies	 the  text  of	the marker.  The exact way the text is
	      displayed may be affected by other options such  as  -anchor  or
	      -rotate.

   WINDOW MARKERS
       A  window marker displays a widget at a given position.	Window markers
       are created with the marker's create operation in  the  form:  pathName
       marker  create window ?option value?...	There may be many option-value
       pairs, each sets a configuration option for  the	 marker.   These  same
       option-value pairs may be used with the marker's configure command.

       The following options are specific to window markers:

       -anchor anchor
	      Anchor  tells  how  to position the widget relative to the posi‐
	      tioning point for the widget. For example, if anchor  is	center
	      then  the	 widget	 is centered on the point; if anchor is n then
	      the widget will be displayed such that the top center  point  of
	      the  rectangular	region	occupied  by the widget will be at the
	      positioning point.  This option defaults to center.

       -height pixels
	      Specifies the height to assign to the marker's window.  If  this
	      option  isn't  specified,	 or if it is specified as "", then the
	      window is given whatever height the widget requests internally.

       -width pixels
	      Specifies the width to assign to the marker's window.   If  this
	      option  isn't  specified,	 or if it is specified as "", then the
	      window is given whatever width the widget requests internally.

       -window pathName
	      Specifies the widget to be managed by  the  barchart.   PathName
	      must be a child of the barchart widget.

GRAPH COMPONENT BINDINGS
       Specific	 barchart  components,	such  as  elements, markers and legend
       entries, can have a command trigger when event  occurs  in  them,  much
       like  canvas  items in Tk's canvas widget.  Not all event sequences are
       valid.  The only binding events that may be specified are those related
       to  the	mouse and keyboard (such as Enter, Leave, ButtonPress, Motion,
       and KeyPress).

       Only one element or marker can be picked during an event.  This	means,
       that  if	 the mouse is directly over both an element and a marker, only
       the uppermost component	is  selected.	This  isn't  true  for	legend
       entries.	  Both	a legend entry and an element (or marker) binding com‐
       mands will be invoked if both items are picked.

       It is possible for multiple bindings to match a particular event.  This
       could occur, for example, if one binding is associated with the element
       name and another is associated with one of the element's tags (see  the
       -bindtags  option).  When this occurs, all of the matching bindings are
       invoked.	 A binding associated with the element name is invoked	first,
       followed	 by  one binding for each of the element's bindtags.  If there
       are multiple matching bindings for a single tag,	 then  only  the  most
       specific	 binding  is  invoked.	A continue command in a binding script
       terminates that script, and a break command terminates that script  and
       skips  any  remaining  scripts for the event, just as for the bind com‐
       mand.

       The -bindtags option for these components controls addition  tag	 names
       which can be matched.  Implicitly elements and markers always have tags
       matching their names.   Setting	the  value  of	the  -bindtags	option
       doesn't change this.

C LANGUAGE API
       You  can	 manipulate  data  elements from the C language.  There may be
       situations where it is too expensive to translate the data values  from
       ASCII  strings.	 Or you might want to read data in a special file for‐
       mat.

       Data can manipulated from the C language using BLT vectors.  You	 spec‐
       ify  the	 X-Y  data coordinates of an element as vectors and manipulate
       the vector from C.  The barchart will be	 redrawn  automatically	 after
       the vectors are updated.

       From Tcl, create the vectors and configure the element to use them.

	      vector X Y
	      .g element configure line1 -xdata X -ydata Y

       To  set	data  points  from C, you pass the values as arrays of doubles
       using the Blt_ResetVector call.	The vector is reset with the new  data
       and  at	the  next  idle	 point (when Tk re-enters its event loop), the
       graph will be redrawn automatically.

	      #include <tcl.h>
	      #include <blt.h>

	      register int i;
	      Blt_Vector *xVec, *yVec;
	      double x[50], y[50];

	      /* Get the BLT vectors "X" and "Y" (created above from Tcl) */
	      if ((Blt_GetVector(interp, "X", 50, &xVec) != TCL_OK) ||
		  (Blt_GetVector(interp, "Y", 50, &yVec) != TCL_OK)) {
		  return TCL_ERROR;
	      }

	      for (i = 0; i < 50; i++) {
		  x[i] = i * 0.02;
		  y[i] = sin(x[i]);
	      }

	      /* Put the data into BLT vectors */
	      if ((Blt_ResetVector(xVec, x, 50, 50, TCL_VOLATILE) != TCL_OK) ||
		  (Blt_ResetVector(yVec, y, 50, 50, TCL_VOLATILE) != TCL_OK)) {
		 return TCL_ERROR;
	      }

       See the vector manual page for more details.

SPEED TIPS
       There may be cases where the bar chart needs to be drawn and updated as
       quickly	as possible.  If drawing speed becomes a big problem, here are
       a few tips to speed up displays.

       · Try to minimize the number of data  points.   The  more  data	points
	 looked at, the more work the bar chart must do.

       · If your data is generated as floating point values, the time required
	 to convert the data values to and from ASCII strings can be  signifi‐
	 cant,	especially when there any many data points.  You can avoid the
	 redundant string-to-decimal conversions using the C API to  BLT  vec‐
	 tors.

       · Don't stipple or dash the element.  Solid bars are much faster.

       · If  you update data elements frequently, try turning off the widget's
	 -bufferelements option.  When the bar chart is	 first	displayed,  it
	 draws	data  elements	into an internal pixmap.  The pixmap acts as a
	 cache, so that when the bar chart needs to be redrawn again, and  the
	 data  elements or coordinate axes haven't changed, the pixmap is sim‐
	 ply copied to the screen.  This is especially	useful	when  you  are
	 using	markers to highlight points and regions on the bar chart.  But
	 if the bar chart is updated frequently, changing either  the  element
	 data or coordinate axes, the buffering becomes redundant.

LIMITATIONS
       Auto-scale  routines  do not use requested min/max limits as boundaries
       when the axis is logarithmically scaled.

       The PostScript output generated for polygons with more than 1500 points
       may  exceed the limits of some printers (See PostScript Language Refer‐
       ence Manual, page 568).	The work-around is to break the	 polygon  into
       separate pieces.

KEYWORDS
       bar chart, widget

BLT				      2.4			   barchart(n)
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