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+<HTML>
+<BODY>
+<PRE>
+<!-- Manpage converted by man2html 3.0.1 -->
+
+</PRE>
+<H2>SYNOPSIS</H2><PRE>
+ <B>barchart</B> <I>pathName</I> ?<I>option</I> <I>value</I>?...
+
+
+</PRE>
+<H2>DESCRIPTION</H2><PRE>
+ The <B>barchart</B> 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.
+
+
+</PRE>
+<H2>INTRODUCTION</H2><PRE>
+ The <B>barchart</B> 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 <I>plotting</I> <I>area</I>. 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 <B>barchart</B> 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
+
+ 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 <B>-weight</B> and <B>-style</B> options).
+
+ postscript
+ The widget can generate encapsulated PostScript output. This
+ component has several options to configure how the PostScript
+ is generated.
+
+
+</PRE>
+<H2>SYNTAX</H2><PRE>
+ <B>barchart</B> <I>pathName</I> ?<I>option</I> <I>value</I>?... The <B>barchart</B> command creates a new
+ window <I>pathName</I> and makes it into a <B>barchart</B> widget. At the time this
+ command is invoked, there must not exist a window named <I>pathName</I>, but
+ <I>pathName</I>'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 <B>configure</B> operation below
+ for the exact details about what <I>option</I> and <I>value</I> pairs are valid.
+
+ If successful, <B>barchart</B> 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: <I>pathName</I> <I>operation</I> ?<I>arg</I>?... Both <I>operation</I> and its argu-
+ ments determine the exact behavior of the command. The operations
+ available for the graph are described in the <B>BARCHART</B> <B>OPERATIONS</B> sec-
+ tion.
+
+ The command can also be used to access components of the graph. <I>path-</I>
+ <I>Name</I> <I>component</I> <I>operation</I> ?<I>arg</I>?... 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.
+
+
+</PRE>
+<H2>EXAMPLE</H2><PRE>
+ The <B>barchart</B> 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 <B>configure</B> operation. #
+ Change the title. .b configure -title "My Plot" To add data elements,
+ you use the command and the <B>element</B> 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 yVec-
+ tor The advantage of using vectors is that when you modify one, the
+ 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 <B>-barmode</B> 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 ele-
+ ments side-by-side. .b configure -barmode aligned By default, the ele-
+ ment's label in the legend will be also e1. You can change the label,
+ or specify no legend entry, again using the element's <B>configure</B> opera-
+ tion. # 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 <B>-mapx</B> and <B>-mapy</B> 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 <B>axis</B> 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 <B>-min</B> and <B>-max</B> 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 the<B>axis</B> <B>configure</B>
+ operations with some user interaction (such as pressing the mouse but-
+ ton), using the <B>bind</B> command. To convert between screen and graph
+ coordinates, use the <B>invtransform</B> operation. # Click the button to set
+ a new minimum bind .b &lt;ButtonPress-1&gt; {
+ %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 <B>-min</B> and <B>-max</B> 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 con-
+ figuration options using the <B>legend</B> 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 <B>-hide</B> option. # Don't display the legend. .b
+ legend configure -hide yes The <B>barchart</B> 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
+ chart into file "file.ps" .b postscript output file.ps -maxpect yes
+ -decorations no This generates a file file.ps containing the encapsu-
+ lated PostScript of the graph. The option <B>-maxpect</B> says to scale the
+ plot to the size of the page. Turning off the <B>-decorations</B> option
+ denotes that no borders or color backgrounds should be drawn (i.e. the
+ background of the margins, legend, and plotting area will be white).
+
+
+</PRE>
+<H2>SYNTAX</H2><PRE>
+ <B>barchart</B> <I>pathName</I> ?<I>option</I> <I>value</I>?... The <B>barchart</B> command creates a new
+ window <I>pathName</I> and makes it into a barchart widget. At the time this
+ command is invoked, there must not exist a window named <I>pathName</I>, but
+ <I>pathName</I>'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 <B>configure</B> operation
+ below for the exact details as to what <I>option</I> and <I>value</I> pairs are
+ valid.
+
+ If successful, <B>barchart</B> returns <I>pathName</I>. It also creates a new Tcl
+ command <I>pathName</I>. This command may be used to invoke various opera-
+ tions to query or modify the bar chart. It has the general form: <I>path-</I>
+ <I>Name</I> <I>operation</I> ?<I>arg</I>?... Both <I>operation</I> and its arguments determine the
+ exact behavior of the command. The operations available for the bar
+ chart are described in the following section.
+
+
+</PRE>
+<H2>BARCHART OPERATIONS</H2><PRE>
+ <I>pathName</I> <B>bar</B> <I>elemName</I> ?<I>option</I> <I>value</I>?...
+ Creates a new barchart element <I>elemName</I>. It's an error if an
+ element <I>elemName</I> already exists. See the manual for <B>barchart</B>
+ for details about what <I>option</I> and <I>value</I> pairs are valid.
+
+ <I>pathName</I> <B>cget</B> <I>option</I>
+ Returns the current value of the configuration option given by
+ <I>option</I>. <I>Option</I> may be any option described below for the <B>con-</B>
+ <B>figure</B> operation.
+
+ <I>pathName</I> <B>configure</B> ?<I>option</I> <I>value</I>?...
+ Queries or modifies the configuration options of the graph. If
+ <I>option</I> isn't specified, a list describing the current options
+ for <I>pathName</I> is returned. If <I>option</I> is specified, but not
+ <I>value</I>, then a list describing <I>option</I> is returned. If one or
+ more <I>option</I> and <I>value</I> pairs are specified, then for each pair,
+ the option <I>option</I> is set to <I>value</I>. The following options are
+ valid.
+
+ <B>-background</B> <I>color</I>
+ Sets the background color. This includes the margins and
+ legend, but not the plotting area.
+
+ <B>-barmode</B> <I>mode</I>
+ Indicates how related bar elements will be drawn.
+ Related elements have data points with the same abscissas
+ (X-coordinates). <I>Mode</I> indicates how those segments should
+
+ <B>-barwidth</B> <I>value</I>
+ Specifies the width of the bars. This value can be over-
+ rided by the individual elements using their <B>-barwidth</B>
+ configuration option. <I>Value</I> is the width in terms of
+ graph-coordinates. The default width is 1.0.
+
+ <B>-borderwidth</B> <I>pixels</I>
+ Sets the width of the 3-D border around the outside edge
+ of the widget. The <B>-relief</B> option determines if the bor-
+ der is to be drawn. The default is 2.
+
+ <B>-bottommargin</B> <I>pixels</I>
+ Specifies the size of the margin below the X-coordinate
+ axis. If <I>pixels</I> is 0, the size of the margin is selected
+ automatically. The default is 0.
+
+ <B>-bufferelements</B> <I>boolean</I>
+ Indicates whether an internal pixmap to buffer the dis-
+ play of data elements should be used. If <I>boolean</I> 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 <B>SPEED</B>
+ <B>TIPS</B> section. The default is 1.
+
+ <B>-cursor</B> <I>cursor</I>
+ Specifies the widget's cursor. The default cursor is
+ crosshair.
+
+ <B>-font</B> <I>fontName</I>
+ Specifies the font of the graph title. The default is
+ *-Helvetica-Bold-R-Normal-*-18-180-*.
+
+ <B>-halo</B> <I>pixels</I>
+ Specifies a maximum distance to consider when searching
+ for the closest data point (see the element's <B>closest</B>
+ operation below). Data points further than <I>pixels</I> away
+ are ignored. The default is 0.5i.
+
+ <B>-height</B> <I>pixels</I>
+ Specifies the requested height of widget. The default is
+ 4i.
+
+ <B>-invertxy</B> <I>boolean</I>
+ Indicates whether the placement X-axis and Y-axis should
+ be inverted. If <I>boolean</I> is true, the X and Y axes are
+ swapped. The default is 0.
+
+ <B>-justify</B> <I>justify</I>
+ Specifies how the title should be justified. This mat-
+ ters only when the title contains more than one line of
+ area. The <B>-plotrelief</B> option determines if a border is
+ drawn. The default is 2.
+
+ <B>-plotpadx</B> <I>pad</I>
+ Sets the amount of padding to be added to the left and
+ right sides of the plotting area. <I>Pad</I> can be a list of
+ one or two screen distances. If <I>pad</I> 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 <I>pad</I>
+ is just one distance, both the left and right sides are
+ padded evenly. The default is 8.
+
+ <B>-plotpady</B> <I>pad</I>
+ Sets the amount of padding to be added to the top and
+ bottom of the plotting area. <I>Pad</I> can be a list of one or
+ two screen distances. If <I>pad</I> has two elements, the top
+ of the plotting area is padded by the first distance and
+ the bottom by the second. If <I>pad</I> is just one distance,
+ both the top and bottom are padded evenly. The default
+ is 8.
+
+ <B>-plotrelief</B> <I>relief</I>
+ Specifies the 3-D effect for the plotting area. <I>Relief</I>
+ 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.
+
+ <B>-relief</B> <I>relief</I>
+ Specifies the 3-D effect for the barchart widget. <I>Relief</I>
+ 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.
+
+ <B>-rightmargin</B> <I>pixels</I>
+ 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 <I>pixels</I> is than 1, the margin
+ size is selected automatically.
+
+ <B>-takefocus</B> <I>focus</I>
+ Provides information used when moving the focus from win-
+ dow to window via keyboard traversal (e.g., Tab and
+ Shift-Tab). If <I>focus</I> 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 "".
+
+ <B>-tile</B> <I>image</I>
+ <B>-width</B> <I>pixels</I>
+ Specifies the requested width of the widget. The default
+ is 5i.
+
+ <I>pathName</I> <B>crosshairs</B> <I>operation</I> ?<I>arg</I>?
+ See the <B>CROSSHAIRS</B> <B>COMPONENT</B> section.
+
+ <I>pathName</I> <B>element</B> <I>operation</I> ?<I>arg</I>?...
+ See the <B>ELEMENT</B> <B>COMPONENTS</B> section.
+
+ <I>pathName</I> <B>extents</B> <I>item</I>
+ Returns the size of a particular item in the graph. <I>Item</I> must
+ be either leftmargin, rightmargin, topmargin, bottommargin,
+ plotwidth, or plotheight.
+
+ <I>pathName</I> <B>grid</B> <I>operation</I> ?<I>arg</I>?...
+ See the <B>GRID</B> <B>COMPONENT</B> section.
+
+ <I>pathName</I> <B>invtransform</B> <I>winX</I> <I>winY</I>
+ 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.
+
+ <I>pathName</I> <B>inside</B> <I>x</I> <I>y</I>
+ Returns 1 is the designated screen-coordinate (<I>x</I> and <I>y</I>) is
+ inside the plotting area and 0 otherwise.
+
+ <I>pathName</I> <B>legend</B> <I>operation</I> ?<I>arg</I>?...
+ See the <B>LEGEND</B> <B>COMPONENT</B> section.
+
+ <I>pathName</I> <B>line</B> <B>operation</B> <B>arg</B>...
+ The operation is the same as <B>element</B>.
+
+ <I>pathName</I> <B>marker</B> <I>operation</I> ?<I>arg</I>?...
+ See the <B>MARKER</B> <B>COMPONENTS</B> section.
+
+ <I>pathName</I> <B>metafile</B> ?<I>fileName</I>?
+ <I>This</I> <I>operation</I> <I>is</I> <I>for</I> <I>Window</I> <I>platforms</I> <I>only</I>. Creates a Windows
+ enhanced metafile of the barchart. If present, <I>fileName</I> is the
+ file name of the new metafile. Otherwise, the metafile is auto-
+ matically added to the clipboard.
+
+ <I>pathName</I> <B>postscript</B> <I>operation</I> ?<I>arg</I>?...
+ See the <B>POSTSCRIPT</B> <B>COMPONENT</B> section.
+
+ <I>pathName</I> <B>snap</B> <I>photoName</I>
+ Takes a snapshot of the graph and stores the contents in the
+ photo image <I>photoName</I>. <I>PhotoName</I> is the name of a Tk photo
+ image that must already exist.
+
+ <I>pathName</I> <B>transform</B> <I>x</I> <I>y</I>
+ 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.
+
+ <B>AXIS</B> <B>COMPONENTS</B>
+ 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 "tem-
+ perature" .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 tempera-
+ ture 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 simultaneously. They are drawn in each of the margins
+ surrounding the plotting area. The axes x and y are drawn in the bot-
+ tom 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: <B>xaxis</B>, <B>yaxis</B>, <B>x2axis</B>, and <B>y2axis</B>. The <B>use</B> operation designates
+ the axis to be drawn in the corresponding margin: <B>xaxis</B> in the bottom,
+ <B>yaxis</B> in the left, <B>x2axis</B> in the top, and <B>y2axis</B> in the right. # Dis-
+ play 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.
+
+
+ <B>-autorange</B> <I>range</I>
+ Sets the range of values for the axis to <I>range</I>. The axis
+ limits are automatically reset to display the most recent
+ data points in this range. If <I>range</I> is 0.0, the range is
+ determined from the limits of the data. If <B>-min</B> or <B>-max</B>
+ are specified, they override this option. The default is
+ 0.0.
+
+ <B>-color</B> <I>color</I>
+ Sets the color of the axis and tick labels. The default
+ is black.
+
+ <B>-command</B> <I>prefix</I>
+ Specifies a Tcl command to be invoked when formatting the
+ axis tick labels. <I>Prefix</I> 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 <I>prefix</I> 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.
+
+ <B>-descending</B> <I>boolean</I>
+ Indicates whether the values along the axis are monotoni-
+ cally increasing or decreasing. If <I>boolean</I> is true, the
+ axis values will be decreasing. The default is 0.
+
+ <B>-hide</B> <I>boolean</I>
+ Indicates whether the axis is displayed.
+
+ <B>-justify</B> <I>justify</I>
+ Specifies how the axis title should be justified. This
+ matters only when the axis title contains more than one
+ line of text. <I>Justify</I> must be left, right, or center.
+ The default is center.
+
+ <B>-limits</B> <I>formatStr</I>
+ 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. <I>FormatStr</I> 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
+ 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
+ <I>boolean</I> is true, the axis range is "loose". The default
+ is 0.
+
+ <B>-majorticks</B> <I>majorList</I>
+ Specifies where to display major axis ticks. You can use
+ this option to display ticks at non-uniform intervals.
+ <I>MajorList</I> is a list of axis coordinates designating the
+ location of major ticks. No minor ticks are drawn. If
+ <I>majorList</I> is "", major ticks will be automatically com-
+ puted. The default is "".
+
+ <B>-max</B> <I>value</I>
+ Sets the maximum limit of <I>axisName</I>. Any data point
+ greater than <I>value</I> is not displayed. If <I>value</I> is "", the
+ maximum limit is calculated using the largest data value.
+ The default is "".
+
+ <B>-min</B> <I>value</I>
+ Sets the minimum limit of <I>axisName</I>. Any data point less
+ than <I>value</I> is not displayed. If <I>value</I> is "", the minimum
+ limit is calculated using the smallest data value. The
+ default is "".
+
+ <B>-minorticks</B> <I>minorList</I>
+ Specifies where to display minor axis ticks. You can use
+ this option to display minor ticks at non-uniform inter-
+ vals. <I>MinorList</I> 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 <B>-majortick</B> option is also
+ set. If <I>minorList</I> is "", minor ticks will be automati-
+ cally computed. The default is "".
+
+ <B>-rotate</B> <I>theta</I>
+ Specifies the how many degrees to rotate the axis tick
+ labels. <I>Theta</I> is a real value representing the number of
+ degrees to rotate the tick labels. The default is 0.0
+ degrees.
+
+ <B>-shiftby</B> <I>value</I>
+ 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 <I>value</I>.
+ You can use this option to prevent the axis limits from
+ being recomputed at each new time point. If <I>value</I> is 0.0,
+ then no automatic shifting is down. The default is 0.0.
+
+ <B>-showticks</B> <I>boolean</I>
+ Indicates whether axis ticks should be drawn. If <I>boolean</I>
+ is true, ticks are drawn. If false, only the axis line
+
+ <B>-tickfont</B> <I>fontName</I>
+ Specifies the font for axis tick labels. The default is
+ *-Courier-Bold-R-Normal-*-100-*.
+
+ <B>-ticklength</B> <I>pixels</I>
+ Sets the length of major and minor ticks (minor ticks are
+ half the length of major ticks). If <I>pixels</I> is less than
+ zero, the axis will be inverted with ticks drawn pointing
+ towards the plot. The default is 0.1i.
+
+ <B>-title</B> <I>text</I>
+ Sets the title of the axis. If <I>text</I> is "", no axis title
+ will be displayed.
+
+ <B>-titlecolor</B> <I>color</I>
+ Sets the color of the axis title. The default is black.
+
+ <B>-titlefont</B> <I>fontName</I>
+ 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 <B>option</B> com-
+ mand. The resource class is Axis. The resource names are the
+ names of the axes (such as x or x2). option add *Bar-
+ chart.Axis.Color blue option add *Barchart.x.LogScale true
+ option add *Barchart.x2.LogScale false
+
+ <I>pathName</I> <B>axis</B> <B>create</B> <I>axisName</I> ?<I>option</I> <I>value</I>?...
+ Creates a new axis by the name <I>axisName</I>. No axis by the same
+ name can already exist. <I>Option</I> and <I>value</I> are described in above
+ in the axis <B>configure</B> operation.
+
+ <I>pathName</I> <B>axis</B> <B>delete</B> ?<I>axisName</I>?...
+ 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.
+
+ <I>pathName</I> <B>axis</B> <B>invtransform</B> <I>axisName</I> <I>value</I>
+ Performs the inverse transformation, changing the screen-coordi-
+ nate <I>value</I> to a graph-coordinate, mapping the value mapped to
+ <I>axisName</I>. Returns the graph-coordinate.
+
+ <I>pathName</I> <B>axis</B> <B>limits</B> <I>axisName</I>
+ Returns a list of the minimum and maximum limits for <I>axisName</I>.
+ The order of the list is min max.
+
+ <I>pathName</I> <B>axis</B> <B>names</B> ?<I>pattern</I>?...
+ Returns a list of axes matching zero or more patterns. If no
+ <I>pattern</I> argument is give, the names of all axes are returned.
+
+ <I>pathName</I> <B>axis</B> <B>transform</B> <I>axisName</I> <I>value</I>
+ Transforms the coordinate <I>value</I> to a screen-coordinate by map-
+
+ right Y-axis.
+
+ They implicitly control the axis that is currently using to that loca-
+ tion. By default, <B>xaxis</B> uses the x axis, <B>yaxis</B> uses y, <B>x2axis</B> uses x2,
+ and <B>y2axis</B> 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 <B>axis</B> component. The <I>axis</I> argument must be <B>xaxis</B>,
+ <B>x2axis</B>, <B>yaxis</B>, or <B>y2axis</B>.
+
+ <I>pathName</I> <I>axis</I> <B>cget</B> <I>option</I>
+
+ <I>pathName</I> <I>axis</I> <B>configure</B> ?<I>option</I> <I>value</I>?...
+
+ <I>pathName</I> <I>axis</I> <B>invtransform</B> <I>value</I>
+
+ <I>pathName</I> <I>axis</I> <B>limits</B>
+
+ <I>pathName</I> <I>axis</I> <B>transform</B> <I>value</I>
+
+ <I>pathName</I> <I>axis</I> <B>use</B> ?<I>axisName</I>?
+ Designates the axis <I>axisName</I> is to be displayed at this loca-
+ tion. <I>AxisName</I> can not be already in use at another location.
+ This command returns the name of the axis currently using this
+ location.
+
+ <B>CROSSHAIRS</B> <B>COMPONENT</B>
+ 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:
+
+ <I>pathName</I> <B>crosshairs</B> <B>cget</B> <I>option</I>
+ Returns the current value of the cross hairs configuration
+ option given by <I>option</I>. <I>Option</I> may be any option described
+ below for the cross hairs <B>configure</B> operation.
+
+ <I>pathName</I> <B>crosshairs</B> <B>configure</B> ?<I>option</I> <I>value</I>?...
+ Queries or modifies the configuration options of the cross
+ hairs. If <I>option</I> isn't specified, a list describing all the
+ current options for the cross hairs is returned. If <I>option</I> is
+ specified, but not <I>value</I>, then a list describing <I>option</I> is
+ returned. If one or more <I>option</I> and <I>value</I> pairs are specified,
+ then for each pair, the cross hairs option <I>option</I> is set to
+ <I>value</I>. The following options are available for cross hairs.
+
+ <B>-linewidth</B> <I>pixels</I>
+ Set the width of the cross hair lines. The default is 1.
+
+ <B>-position</B> <I>pos</I>
+ Specifies the screen position where the cross hairs
+ intersect. <I>Pos</I> must be in the form "<I>@x,y</I>", where <I>x</I> and <I>y</I>
+ are the window coordinates of the intersection.
+
+ Cross hairs configuration options may be also be set by the
+ <B>option</B> command. The resource name and class are crosshairs and
+ Crosshairs respectively. option add *Bar-
+ chart.Crosshairs.LineWidth 2 option add *Bar-
+ chart.Crosshairs.Color red
+
+ <I>pathName</I> <B>crosshairs</B> <B>off</B>
+ Turns off the cross hairs.
+
+ <I>pathName</I> <B>crosshairs</B> <B>on</B>
+ Turns on the display of the cross hairs.
+
+ <I>pathName</I> <B>crosshairs</B> <B>toggle</B>
+ Toggles the current state of the cross hairs, alternately map-
+ ping and unmapping the cross hairs.
+
+
+</PRE>
+<H2>ELEMENTS</H2><PRE>
+ 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.
+
+ <I>pathName</I> <B>element</B> <B>activate</B> <I>elemName</I> ?<I>index</I>?...
+ Specifies the data points of element <I>elemName</I> to be drawn using
+ active foreground and background colors. <I>ElemName</I> is the name
+ of the element and <I>index</I> is a number representing the index of
+ the data point. If no indices are present then all data points
+ become active.
+
+ <I>pathName</I> <B>element</B> <B>bind</B> <I>tagName</I> ?<I>sequence</I>? ?<I>command</I>?
+ Associates <I>command</I> with <I>tagName</I> such that whenever the event
+ sequence given by <I>sequence</I> occurs for an element with this tag,
+ <I>command</I> will be invoked. The syntax is similar to the <B>bind</B> com-
+ mand except that it operates on graph elements, rather than wid-
+ gets. See the <B>bind</B> manual entry for complete details on <I>sequence</I>
+ and the substitutions performed on <I>command</I> before invoking it.
+
+
+ <I>pathName</I> <B>element</B> <B>closest</B> <I>x</I> <I>y</I> ?<I>option</I> <I>value</I>?... ?<I>elemName</I>?...
+ Finds the data point representing the bar closest to the window
+ coordinates <I>x</I> and <I>y</I> in the element <I>elemName</I>. <I>ElemName</I> is the
+ name of an element, which must be currently displayed. If no
+ elements are specified, then all displayed elements are
+ searched. It returns a key-value 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
+ <I>option</I>-<I>value</I> pairs are available.
+
+ <B>-halo</B> <I>pixels</I>
+ Specifies a threshold distance where selected data points
+ are ignored. <I>Pixels</I> 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 <B>barchart</B>'s <B>-halo</B> option.
+
+ <I>pathName</I> <B>element</B> <B>configure</B> <I>elemName</I> ?<I>elemName</I>... ?<I>option</I> <I>value</I>?...
+ Queries or modifies the configuration options for elements.
+ Several elements can be modified at the same time. If <I>option</I>
+ isn't specified, a list describing all the current options for
+ <I>elemName</I> is returned. If <I>option</I> is specified, but not <I>value</I>,
+ then a list describing the option <I>option</I> is returned. If one or
+ more <I>option</I> and <I>value</I> pairs are specified, then for each pair,
+ the element option <I>option</I> is set to <I>value</I>. The following
+ options are valid for elements.
+
+ <B>-activepen</B> <I>penName</I>
+ Specifies pen to use to draw active element. If <I>penName</I>
+ is "", no active elements will be drawn. The default is
+ activeLine.
+
+ <B>-bindtags</B> <I>tagList</I>
+ Specifies the binding tags for the element. <I>TagList</I> 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.
+
+ <B>-background</B> <I>color</I>
+ Sets the the color of the border around each bar. The
+ default is white.
+
+ <B>-barwidth</B> <I>value</I>
+ Specifies the width the bars drawn for the element.
+ <I>Value</I> is the width in X-coordinates. If this option
+ isn't specified, the width of each bar is the value of
+ the widget's <B>-barwidth</B> option.
+
+ a list of numeric expressions representing the X-Y coor-
+ dinate pairs of each data point.
+
+ <B>-foreground</B> <I>color</I>
+ Sets the color of the interior of the bars.
+
+ <B>-hide</B> <I>boolean</I>
+ Indicates whether the element is displayed. The default
+ is no.
+
+ <B>-label</B> <I>text</I>
+ Sets the element's label in the legend. If <I>text</I> is "",
+ the element will have no entry in the legend. The
+ default label is the element's name.
+
+ <B>-mapx</B> <I>xAxis</I>
+ Selects the X-axis to map the element's X-coordinates
+ onto. <I>XAxis</I> must be the name of an axis. The default is
+ x.
+
+ <B>-mapy</B> <I>yAxis</I>
+ Selects the Y-axis to map the element's Y-coordinates
+ onto. <I>YAxis</I> must be the name of an axis. The default is
+ y.
+
+ <B>-relief</B> <I>string</I>
+ Specifies the 3-D effect desired for bars. <I>Relief</I> 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.
+
+ <B>-stipple</B> <I>bitmap</I>
+ Specifies a stipple pattern with which to draw the bars.
+ If <I>bitmap</I> is "", then the bar is drawn in a solid fash-
+ ion.
+
+ <B>-xdata</B> <I>xVector</I>
+ Specifies the x-coordinate vector of the data. <I>XVector</I>
+ is the name of a BLT vector or a list of numeric expres-
+ sions.
+
+ <B>-ydata</B> <I>yVector</I>
+ Specifies the y-coordinate vector of the data. <I>YVector</I>
+ is the name of a BLT vector or a list of numeric expres-
+ sions.
+
+ Element configuration options may also be set by the <B>option</B> com-
+ mand. The resource names in the option database are prefixed
+ by elem. option add *Barchart.Element.background blue
+
+ <I>pathName</I> <B>element</B> <B>create</B> <I>elemName</I> ?<I>option</I> <I>value</I>?...
+
+ <I>pathName</I> <B>element</B> <B>exists</B> <I>elemName</I>
+ Returns 1 if an element <I>elemName</I> currently exists and 0 other-
+ wise.
+
+ <I>pathName</I> <B>element</B> <B>names</B> ?<I>pattern</I>?...
+ Returns the elements matching one or more pattern. If no <I>pat-</I>
+ <I>tern</I> is given, the names of all elements is returned.
+
+ <I>pathName</I> <B>element</B> <B>show</B> ?<I>nameList</I>?
+ Queries or modifies the element display list. The element dis-
+ play list designates the elements drawn and in what order.
+ <I>NameList</I> is a list of elements to be displayed in the order they
+ are named. If there is no <I>nameList</I> argument, the current dis-
+ play list is returned.
+
+ <I>pathName</I> <B>element</B> <B>type</B> <I>elemName</I>
+ Returns the type of <I>elemName</I>. If the element is a bar element,
+ the commands returns the string "bar", otherwise it returns
+ "line".
+
+ <B>GRID</B> <B>COMPONENT</B>
+ 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.
+
+ <I>pathName</I> <B>grid</B> <B>cget</B> <I>option</I>
+ Returns the current value of the grid line configuration option
+ given by <I>option</I>. <I>Option</I> may be any option described below for
+ the grid <B>configure</B> operation.
+
+ <I>pathName</I> <B>grid</B> <B>configure</B> ?<I>option</I> <I>value</I>?...
+ Queries or modifies the configuration options for grid lines.
+ If <I>option</I> isn't specified, a list describing all the current
+ grid options for <I>pathName</I> is returned. If <I>option</I> is specified,
+ but not <I>value</I>, then a list describing <I>option</I> is returned. If
+ one or more <I>option</I> and <I>value</I> pairs are specified, then for each
+ pair, the grid line option <I>option</I> is set to <I>value</I>. The follow-
+ ing options are valid for grid lines.
+
+ <B>-color</B> <I>color</I>
+ Sets the color of the grid lines. The default is black.
+
+ <B>-dashes</B> <I>dashList</I>
+ Sets the dash style of the grid lines. <I>DashList</I> 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 <I>dashList</I> is "", the
+ grid will be solid lines.
+
+ <B>-hide</B> <I>boolean</I>
+ Indicates whether the grid should be drawn. If <I>boolean</I> is
+
+ <B>-minor</B> <I>boolean</I>
+ Indicates whether the grid lines should be drawn for
+ minor ticks. If <I>boolean</I> is true, the lines will appear
+ at minor tick intervals. The default is 1.
+
+ Grid configuration options may also be set by the <B>option</B> com-
+ mand. The resource name and class are grid and Grid respec-
+ tively. option add *Barchart.grid.LineWidth 2 option add *Bar-
+ chart.Grid.Color black
+
+ <I>pathName</I> <B>grid</B> <B>off</B>
+ Turns off the display the grid lines.
+
+ <I>pathName</I> <B>grid</B> <B>on</B>
+ Turns on the display the grid lines.
+
+ <I>pathName</I> <B>grid</B> <B>toggle</B>
+ Toggles the display of the grid.
+
+ <B>LEGEND</B> <B>COMPONENT</B>
+ 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.
+
+ <I>pathName</I> <B>legend</B> <B>activate</B> <I>pattern</I>...
+ Selects legend entries to be drawn using the active legend col-
+ ors and relief. All entries whose element names match <I>pattern</I>
+ are selected. To be selected, the element name must match only
+ one <I>pattern</I>.
+
+ <I>pathName</I> <B>legend</B> <B>bind</B> <I>tagName</I> ?<I>sequence</I>? ?<I>command</I>?
+ Associates <I>command</I> with <I>tagName</I> such that whenever the event
+ sequence given by <I>sequence</I> occurs for a legend entry with this
+ tag, <I>command</I> will be invoked. Implicitly the element names in
+ the entry are tags. The syntax is similar to the <B>bind</B> command
+ except that it operates on legend entries, rather than widgets.
+ See the <B>bind</B> manual entry for complete details on <I>sequence</I> and
+ the substitutions performed on <I>command</I> before invoking it.
+
+ If all arguments are specified then a new binding is created,
+ replacing any existing binding for the same <I>sequence</I> and <I>tag-</I>
+ <I>Name</I>. If the first character of <I>command</I> is + then <I>command</I> aug-
+ ments an existing binding rather than replacing it. If no <I>com-</I>
+ <I>mand</I> argument is provided then the command currently associated
+ with <I>tagName</I> and <I>sequence</I> (it's an error occurs if there's no
+ such binding) is returned. If both <I>command</I> and <I>sequence</I> are
+ missing then a list of all the event sequences for which bind-
+ ings have been defined for <I>tagName</I>.
+
+ <B>-activebackground</B> <I>color</I>
+ Sets the background color for active legend entries. All
+ legend entries marked active (see the legend <B>activate</B>
+ operation) are drawn using this background color.
+
+ <B>-activeborderwidth</B> <I>pixels</I>
+ Sets the width of the 3-D border around the outside edge
+ of the active legend entries. The default is 2.
+
+ <B>-activeforeground</B> <I>color</I>
+ Sets the foreground color for active legend entries. All
+ legend entries marked as active (see the legend <B>activate</B>
+ operation) are drawn using this foreground color.
+
+ <B>-activerelief</B> <I>relief</I>
+ Specifies the 3-D effect desired for active legend
+ entries. <I>Relief</I> 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.
+
+ <B>-anchor</B> <I>anchor</I>
+ Tells how to position the legend relative to the posi-
+ tioning point for the legend. This is dependent on the
+ value of the <B>-position</B> 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 <I>anchor</I> is center then the legend
+ is centered on the point; if <I>anchor</I> 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 <I>anchor</I> is center then the legend is
+ centered in the plotting area; if <I>anchor</I> is
+ ne then the legend will be drawn such that
+ occupies the upper right corner of the plot-
+ ting area.
+
+ of the legend (if such border is being drawn; the <B>relief</B>
+ option determines this). The default is 2 pixels.
+
+ <B>-font</B> <I>fontName</I>
+ <I>FontName</I> 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-*.
+
+ <B>-foreground</B> <I>color</I>
+ Sets the foreground color of the text drawn for the ele-
+ ment's label. The default is black.
+
+ <B>-hide</B> <I>boolean</I>
+ Indicates whether the legend should be displayed. If
+ <I>boolean</I> is true, the legend will not be draw. The
+ default is no.
+
+ <B>-ipadx</B> <I>pad</I>
+ Sets the amount of internal padding to be added to the
+ width of each legend entry. <I>Pad</I> can be a list of one or
+ two screen distances. If <I>pad</I> has two elements, the left
+ side of the legend entry is padded by the first distance
+ and the right side by the second. If <I>pad</I> is just one
+ distance, both the left and right sides are padded
+ evenly. The default is 2.
+
+ <B>-ipady</B> <I>pad</I>
+ Sets an amount of internal padding to be added to the
+ height of each legend entry. <I>Pad</I> can be a list of one or
+ two screen distances. If <I>pad</I> has two elements, the top
+ of the entry is padded by the first distance and the bot-
+ tom by the second. If <I>pad</I> is just one distance, both the
+ top and bottom of the entry are padded evenly. The
+ default is 2.
+
+ <B>-padx</B> <I>pad</I>
+ Sets the padding to the left and right exteriors of the
+ legend. <I>Pad</I> can be a list of one or two screen dis-
+ tances. If <I>pad</I> has two elements, the left side of the
+ legend is padded by the first distance and the right side
+ by the second. If <I>pad</I> has just one distance, both the
+ left and right sides are padded evenly. The default is
+ 4.
+
+ <B>-pady</B> <I>pad</I>
+ Sets the padding above and below the legend. <I>Pad</I> can be
+ a list of one or two screen distances. If <I>pad</I> has two
+ elements, the area above the legend is padded by the
+ first distance and the area below by the second. If <I>pad</I>
+ is just one distance, both the top and bottom areas are
+ padded evenly. The default is 0.
+
+ drawn on top of any elements that may overlap it. The
+ default is no.
+
+ <B>-relief</B> <I>relief</I>
+ Specifies the 3-D effect for the border around the leg-
+ end. <I>Relief</I> 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 <B>option</B> 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
+
+ <I>pathName</I> <B>legend</B> <B>deactivate</B> <I>pattern</I>...
+ Selects legend entries to be drawn using the normal legend col-
+ ors and relief. All entries whose element names match <I>pattern</I>
+ are selected. To be selected, the element name must match only
+ one <I>pattern</I>.
+
+ <I>pathName</I> <B>legend</B> <B>get</B> <I>pos</I>
+ Returns the name of the element whose entry is at the screen
+ position <I>pos</I> in the legend. <I>Pos</I> must be in the form "<I>@x,y</I>",
+ where <I>x</I> and <I>y</I> are window coordinates. If the given coordinates
+ do not lie over a legend entry, "" is returned.
+
+ <B>PEN</B> <B>COMPONENTS</B>
+ 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 <B>-weight</B> and <B>-style</B> 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 sev-
+ eral 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 <B>-pen</B> or <B>-activepen</B> 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
+ <B>-styles</B> 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.
+ <I>value</I>. The following options are valid for pens.
+
+ <B>-background</B> <I>color</I>
+ Sets the the color of the border around each bar. The
+ default is white.
+
+ <B>-borderwidth</B> <I>pixels</I>
+ Sets the border width of the 3-D border drawn around the
+ outside of each bar. The <B>-relief</B> option determines if
+ such a border is drawn. <I>Pixels</I> must be a valid screen
+ distance like 2 or 0.25i. The default is 2.
+
+ <B>-foreground</B> <I>color</I>
+ Sets the color of the interior of the bars.
+
+ <B>-relief</B> <I>string</I>
+ Specifies the 3-D effect desired for bars. <I>Relief</I> 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.
+
+ <B>-stipple</B> <I>bitmap</I>
+ Specifies a stipple pattern with which to draw the bars.
+ If <I>bitmap</I> is "", then the bar is drawn in a solid fash-
+ ion.
+
+ <B>-type</B> <I>elemType</I>
+ 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 <B>option</B> 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
+
+ <I>pathName</I> <B>pen</B> <B>create</B> <I>penName</I> ?<I>option</I> <I>value</I>?...
+ Creates a new pen by the name <I>penName</I>. No pen by the same name
+ can already exist. <I>Option</I> and <I>value</I> are described in above in
+ the pen <B>configure</B> operation.
+
+ <I>pathName</I> <B>pen</B> <B>delete</B> ?<I>penName</I>?...
+ 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.
+
+ <I>pathName</I> <B>pen</B> <B>names</B> ?<I>pattern</I>?...
+ Returns a list of pens matching zero or more patterns. If no
+ <I>option</I>. <I>Option</I> may be any option described below for the post-
+ script <B>configure</B> operation.
+
+ <I>pathName</I> <B>postscript</B> <B>configure</B> ?<I>option</I> <I>value</I>?...
+ Queries or modifies the configuration options for PostScript
+ generation. If <I>option</I> isn't specified, a list describing the
+ current postscript options for <I>pathName</I> is returned. If <I>option</I>
+ is specified, but not <I>value</I>, then a list describing <I>option</I> is
+ returned. If one or more <I>option</I> and <I>value</I> pairs are specified,
+ then for each pair, the postscript option <I>option</I> is set to
+ <I>value</I>. The following postscript options are available.
+
+ <B>-center</B> <I>boolean</I>
+ Indicates whether the plot should be centered on the
+ PostScript page. If <I>boolean</I> is false, the plot will be
+ placed in the upper left corner of the page. The default
+ is 1.
+
+ <B>-colormap</B> <I>varName</I>
+ <I>VarName</I> 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 <I>varName</I> 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 <I>varName</I> 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 <I>varName</I> for a given color, then it uses
+ the red, green, and blue intensities from the X color.
+
+ <B>-colormode</B> <I>mode</I>
+ Specifies how to output color information. <I>Mode</I> 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.
+
+ <B>-fontmap</B> <I>varName</I>
+ <I>VarName</I> 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 <I>varName</I> 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 <I>varName</I> 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
+ widget's height. The default is 0.
+
+ <B>-landscape</B> <I>boolean</I>
+ If <I>boolean</I> 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.
+
+ <B>-maxpect</B> <I>boolean</I>
+ 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.
+
+ <B>-padx</B> <I>pad</I>
+ Sets the horizontal padding for the left and right page
+ borders. The borders are exterior to the plot. <I>Pad</I> can
+ be a list of one or two screen distances. If <I>pad</I> has two
+ elements, the left border is padded by the first distance
+ and the right border by the second. If <I>pad</I> has just one
+ distance, both the left and right borders are padded
+ evenly. The default is 1i.
+
+ <B>-pady</B> <I>pad</I>
+ Sets the vertical padding for the top and bottom page
+ borders. The borders are exterior to the plot. <I>Pad</I> can
+ be a list of one or two screen distances. If <I>pad</I> has two
+ elements, the top border is padded by the first distance
+ and the bottom border by the second. If <I>pad</I> has just one
+ distance, both the top and bottom borders are padded
+ evenly. The default is 1i.
+
+ <B>-paperheight</B> <I>pixels</I>
+ 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.
+
+ <B>-paperwidth</B> <I>pixels</I>
+ 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.
+
+ <B>-width</B> <I>pixels</I>
+ Sets the width of the plot. This lets you generate a
+ plot of a width different from that of the widget. If
+ <I>pixels</I> 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
+ <B>option</B> command. The resource name and class are postscript and
+ Postscript respectively. option add *Barchart.postscript.Deco-
+
+ 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 <B>-under</B> option.
+
+ Markers, in contrast to elements, don't affect the scaling of the coor-
+ dinate axes. They can also have <I>elastic</I> 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.
+
+ <I>pathName</I> <B>marker</B> <B>after</B> <I>markerId</I> ?<I>afterId</I>?
+ Changes the order of the markers, drawing the first marker after
+ the second. If no second <I>afterId</I> 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.
+
+ <I>pathName</I> <B>marker</B> <B>before</B> <I>markerId</I> ?<I>beforeId</I>?
+ Changes the order of the markers, drawing the first marker
+ before the second. If no second <I>beforeId</I> 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.
+
+ <I>pathName</I> <B>marker</B> <B>bind</B> <I>tagName</I> ?<I>sequence</I>? ?<I>command</I>?
+ Associates <I>command</I> with <I>tagName</I> such that whenever the event
+ sequence given by <I>sequence</I> occurs for a marker with this tag,
+ <I>command</I> will be invoked. The syntax is similar to the <B>bind</B> com-
+ mand except that it operates on graph markers, rather than wid-
+ gets. See the <B>bind</B> manual entry for complete details on <I>sequence</I>
+ and the substitutions performed on <I>command</I> before invoking it.
+
+ If all arguments are specified then a new binding is created,
+ replacing any existing binding for the same <I>sequence</I> and <I>tag-</I>
+ <I>Name</I>. If the first character of <I>command</I> is + then <I>command</I> aug-
+ ments an existing binding rather than replacing it. If no <I>com-</I>
+ <I>mand</I> argument is provided then the command currently associated
+ with <I>tagName</I> and <I>sequence</I> (it's an error occurs if there's no
+ such binding) is returned. If both <I>command</I> and <I>sequence</I> are
+ missing then a list of all the event sequences for which bind-
+ ings have been defined for <I>tagName</I>.
+
+ <I>pathName</I> <B>marker</B> <B>cget</B> <I>option</I>
+ Returns the current value of the marker configuration option
+ given by <I>option</I>. <I>Option</I> may be any option described below in
+ the <B>configure</B> operation.
+
+ <I>pathName</I> <B>marker</B> <B>configure</B> <I>markerId</I> ?<I>option</I> <I>value</I>?...
+ 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.
+
+ <B>-coords</B> <I>coordList</I>
+ Specifies the coordinates of the marker. <I>CoordList</I> 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 <I>coordList</I> is "", the marker
+ will not be displayed. The default is "".
+
+ <B>-element</B> <I>elemName</I>
+ Links the marker with the element <I>elemName</I>. The marker
+ is drawn only if the element is also currently displayed
+ (see the element's <B>show</B> operation). If <I>elemName</I> is "",
+ the marker is always drawn. The default is "".
+
+ <B>-hide</B> <I>boolean</I>
+ Indicates whether the marker is drawn. If <I>boolean</I> is
+ true, the marker is not drawn. The default is no.
+
+ <B>-mapx</B> <I>xAxis</I>
+ Specifies the X-axis to map the marker's X-coordinates
+ onto. <I>XAxis</I> must the name of an axis. The default is x.
+
+ <B>-mapy</B> <I>yAxis</I>
+ Specifies the Y-axis to map the marker's Y-coordinates
+ onto. <I>YAxis</I> must the name of an axis. The default is y.
+
+ <B>-name</B> <I>markerId</I>
+ Changes the identifier for the marker. The identifier
+ <I>markerId</I> can not already be used by another marker. If
+ this option isn't specified, the marker's name is
+ uniquely generated.
+
+ <B>-under</B> <I>boolean</I>
+ Indicates whether the marker is drawn below/above data
+ elements. If <I>boolean</I> 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.
+
+ <B>-xoffset</B> <I>pixels</I>
+ Specifies a screen distance to offset the marker horizon-
+ tally. <I>Pixels</I> is a valid screen distance, such as 2 or
+ 1.2i. The default is 0.
+
+ Creates a marker of the selected type. <I>Type</I> may be either text,
+ line, bitmap, image, polygon, or window. This command returns
+ the marker identifier, used as the <I>markerId</I> argument in the
+ other marker-related commands. If the <B>-name</B> 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.
+
+ <I>pathName</I> <B>marker</B> <B>delete</B> ?<I>name</I>?...
+ Removes one of more markers. The graph will automatically be
+ redrawn without the marker..
+
+ <I>pathName</I> <B>marker</B> <B>exists</B> <I>markerId</I>
+ Returns 1 if the marker <I>markerId</I> exists and 0 otherwise.
+
+ <I>pathName</I> <B>marker</B> <B>names</B> ?<I>pattern</I>?
+ Returns the names of all the markers that currently exist. If
+ <I>pattern</I> is supplied, only those markers whose names match it
+ will be returned.
+
+ <I>pathName</I> <B>marker</B> <B>type</B> <I>markerId</I>
+ Returns the type of the marker given by <I>markerId</I>, such as line
+ or text. If <I>markerId</I> is not a valid a marker identifier, "" is
+ returned.
+
+ <B>BITMAP</B> <B>MARKERS</B>
+ 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 <B>create</B> operation in the
+ form: <I>pathName</I> <B>marker</B> <B>create</B> <B>bitmap</B> ?<I>option</I> <I>value</I>?... There may be
+ many <I>option</I>-<I>value</I> pairs, each sets a configuration options for the
+ marker. These same <I>option</I>-<I>value</I> pairs may be used with the marker's
+ <B>configure</B> operation.
+
+ The following options are specific to bitmap markers:
+
+ <B>-background</B> <I>color</I>
+ Same as the <B>-fill</B> option.
+
+ <B>-bitmap</B> <I>bitmap</I>
+ Specifies the bitmap to be displayed. If <I>bitmap</I> is "", the
+ marker will not be displayed. The default is "".
+
+ <B>-fill</B> <I>color</I>
+ Sets the background color of the bitmap. If <I>color</I> is the empty
+ string, no background will be transparent. The default back-
+
+ <B>-rotate</B> <I>theta</I>
+ Sets the rotation of the bitmap. <I>Theta</I> 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.
+
+ <B>IMAGE</B> <B>MARKERS</B>
+ A image marker displays an image. Image markers are created with the
+ marker's <B>create</B> operation in the form: <I>pathName</I> <B>marker</B> <B>create</B> <B>image</B>
+ ?<I>option</I> <I>value</I>?... There may be many <I>option</I>-<I>value</I> pairs, each sets a
+ configuration option for the marker. These same <I>option</I>-<I>value</I> pairs may
+ be used with the marker's <B>configure</B> operation.
+
+ The following options are specific to image markers:
+
+ <B>-anchor</B> <I>anchor</I>
+ <I>Anchor</I> tells how to position the image relative to the position-
+ ing point for the image. For example, if <I>anchor</I> is center then
+ the image is centered on the point; if <I>anchor</I> is n then the
+ image will be drawn such that the top center point of the rect-
+ angular region occupied by the image will be at the positioning
+ point. This option defaults to center.
+
+ <B>-image</B> <I>image</I>
+ Specifies the image to be drawn. If <I>image</I> is "", the marker
+ will not be drawn. The default is "".
+
+ <B>LINE</B> <B>MARKERS</B>
+ A line marker displays one or more connected line segments. Line mark-
+ ers are created with marker's <B>create</B> operation in the form: <I>pathName</I>
+ <B>marker</B> <B>create</B> <B>line</B> ?<I>option</I> <I>value</I>?... There may be many <I>option</I>-<I>value</I>
+ pairs, each sets a configuration option for the marker. These same
+ <I>option</I>-<I>value</I> pairs may be used with the marker's <B>configure</B> operation.
+
+ The following options are specific to line markers:
+
+ <B>-dashes</B> <I>dashList</I>
+ Sets the dash style of the line. <I>DashList</I> 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
+ <I>dashList</I> is "", the marker line will be solid.
+
+ <B>-fill</B> <I>color</I>
+ Sets the background color of the line. This color is used with
+ striped lines (see the <B>-dashes</B> option). If <I>color</I> is the empty
+ string, no background color is drawn (the line will be dashed,
+ not striped). The default background color is "".
+
+ <B>-linewidth</B> <I>pixels</I>
+ Sets the width of the lines. The default width is 0.
+
+ in the form: <I>pathName</I> <B>marker</B> <B>create</B> <B>polygon</B> ?<I>option</I> <I>value</I>?... There
+ may be many <I>option</I>-<I>value</I> pairs, each sets a configuration option for
+ the marker. These same <I>option</I>-<I>value</I> pairs may be used with the <B>marker</B>
+ <B>configure</B> command to change the marker's configuration. The following
+ options are supported for polygon markers:
+
+ <B>-dashes</B> <I>dashList</I>
+ Sets the dash style of the outline of the polygon. <I>DashList</I> 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 <I>dashList</I> is "", the outline will be a
+ solid line.
+
+ <B>-fill</B> <I>color</I>
+ Sets the fill color of the polygon. If <I>color</I> is "", then the
+ interior of the polygon is transparent. The default is white.
+
+ <B>-linewidth</B> <I>pixels</I>
+ Sets the width of the outline of the polygon. If <I>pixels</I> is zero,
+ no outline is drawn. The default is 0.
+
+ <B>-outline</B> <I>color</I>
+ Sets the color of the outline of the polygon. If the polygon is
+ stippled (see the <B>-stipple</B> option), then this represents the
+ foreground color of the stipple. The default is black.
+
+ <B>-stipple</B> <I>bitmap</I>
+ Specifies that the polygon should be drawn with a stippled pat-
+ tern rather than a solid color. <I>Bitmap</I> specifies a bitmap to use
+ as the stipple pattern. If <I>bitmap</I> is "", then the polygon is
+ filled with a solid color (if the <B>-fill</B> option is set). The
+ default is "".
+
+ <B>TEXT</B> <B>MARKERS</B>
+ 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 <B>create</B>
+ operation in the form: <I>pathName</I> <B>marker</B> <B>create</B> <B>text</B> ?<I>option</I> <I>value</I>?...
+ There may be many <I>option</I>-<I>value</I> pairs, each sets a configuration option
+ for the text marker. These same <I>option</I>-<I>value</I> pairs may be used with
+ the marker's <B>configure</B> operation.
+
+ The following options are specific to text markers:
+
+ <B>-anchor</B> <I>anchor</I>
+ <I>Anchor</I> tells how to position the text relative to the position-
+ ing point for the text. For example, if <I>anchor</I> is center then
+ the text is centered on the point; if <I>anchor</I> 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.
+
+
+ <B>-justify</B> <I>justify</I>
+ Specifies how the text should be justified. This matters only
+ when the marker contains more than one line of text. <I>Justify</I>
+ must be left, right, or center. The default is center.
+
+ <B>-outline</B> <I>color</I>
+ Sets the color of the text. The default value is black.
+
+ <B>-padx</B> <I>pad</I>
+ Sets the padding to the left and right exteriors of the text.
+ <I>Pad</I> can be a list of one or two screen distances. If <I>pad</I> has
+ two elements, the left side of the text is padded by the first
+ distance and the right side by the second. If <I>pad</I> has just one
+ distance, both the left and right sides are padded evenly. The
+ default is 4.
+
+ <B>-pady</B> <I>pad</I>
+ Sets the padding above and below the text. <I>Pad</I> can be a list of
+ one or two screen distances. If <I>pad</I> has two elements, the area
+ above the text is padded by the first distance and the area
+ below by the second. If <I>pad</I> is just one distance, both the top
+ and bottom areas are padded evenly. The default is 4.
+
+ <B>-rotate</B> <I>theta</I>
+ Specifies the number of degrees to rotate the text. <I>Theta</I> 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.
+
+ <B>-text</B> <I>text</I>
+ Specifies the text of the marker. The exact way the text is
+ displayed may be affected by other options such as <B>-anchor</B> or
+ <B>-rotate</B>.
+
+ <B>WINDOW</B> <B>MARKERS</B>
+ A window marker displays a widget at a given position. Window markers
+ are created with the marker's <B>create</B> operation in the form: <I>pathName</I>
+ <B>marker</B> <B>create</B> <B>window</B> ?<I>option</I> <I>value</I>?... There may be many <I>option</I>-<I>value</I>
+ pairs, each sets a configuration option for the marker. These same
+ <I>option</I>-<I>value</I> pairs may be used with the marker's <B>configure</B> command.
+
+ The following options are specific to window markers:
+
+ <B>-anchor</B> <I>anchor</I>
+ <I>Anchor</I> tells how to position the widget relative to the posi-
+ tioning point for the widget. For example, if <I>anchor</I> is center
+ then the widget is centered on the point; if <I>anchor</I> 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.
+
+
+</PRE>
+<H2>GRAPH COMPONENT BINDINGS</H2><PRE>
+ 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 <B>Enter</B>, <B>Leave</B>, <B>ButtonPress</B>, <B>Motion</B>,
+ and <B>KeyPress</B>).
+
+ 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
+ <B>-bindtags</B> 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 <B>-bindtags</B> 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 <B>-bindtags</B> option
+ doesn't change this.
+
+
+</PRE>
+<H2>C LANGUAGE API</H2><PRE>
+ 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
+ <B>Blt_ResetVector</B> 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 &lt;tcl.h&gt; #include &lt;blt.h&gt;
+
+ register int i; Blt_Vector *xVec, *yVec; double x[50], y[50];
+
+ /* Get the BLT vectors "X" and "Y" (created above from Tcl) */ if
+ 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.
+
+ <B>o</B> Try to minimize the number of data points. The more data points
+ looked at, the more work the bar chart must do.
+
+ <B>o</B> 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.
+
+ <B>o</B> Don't stipple or dash the element. Solid bars are much faster.
+
+ <B>o</B> If you update data elements frequently, try turning off the widget's
+ <B>-bufferelements</B> 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.
+
+
+</PRE>
+<H2>LIMITATIONS</H2><PRE>
+ 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.
+
+
+</PRE>
+<H2>KEYWORDS</H2><PRE>
+ bar chart, widget
+
+
+
+BLT BLT_VERSION barchart(n)
+</PRE>
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