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<A HREF="#toc">Table of Contents</A><P>
 
<H2><A NAME="sect0" HREF="#toc0">Name</A></H2>
eps -  Encapsulated PostScript canvas item. 
<H2><A NAME="sect1" HREF="#toc1">Synopsis</A></H2>
<I>canvas<B>
create eps <I>x y </I></B></I>?<I>option value</I>?... 
<H2><A NAME="sect2" HREF="#toc2">Description</A></H2>
The <B>eps</B> canvas item lets you place
encapsulated PostScript (EPS) on a canvas, controlling its size and placement.
 The EPS item is displayed either as a solid rectangle or a preview image.
 The preview image is designated in one of two ways: 1) the EPS file contains
an ASCII hexadecimal preview, or 2) a Tk photo image.  When the canvas generates
PostScript output, the EPS will be inserted with the proper translation
and scaling to match that of the EPS item. So can use the canvas widget
as a page layout tool. 
<H2><A NAME="sect3" HREF="#toc3">Example</A></H2>
Let's say you have for PostScript files of
four graphs which you want to tile two-by-two on a single page.  Maybe you'd
like to annotate the graphs by putting a caption at the bottom of each
graph. <P>
Normally, you would have to resort to an external tool or write your
own PostScript program.  The <B>eps</B> canvas item lets you do this through Tk's
canvas widget.  An <B>eps</B> item displays an image (or rectangle) representing
the encapsulated PostScript file. It also scales and translates the EPS
file when the canvas is printed. <P>
 
<H2><A NAME="sect4" HREF="#toc4">Syntax</A></H2>
<BR>
<P>
<CODE><I>canvas <B>create eps <I>x y </I></B></I>?<I>option value</I>?...<BR>
</CODE><P>The <B>eps</B> item creates a new canvas item. <I>Canvas</I> is the name of a <B>canvas</B> widget.
 You must supply the X-Y coordinate of the new eps item.  How the coordinate
is exactly interpreted is controlled by the <B>-anchor</B> option (see below).
<P>
Additional options may be specified on the command line to configure aspects
of the eps item such as its color, stipple, and font.  The following <I>option</I>
and <I>value</I> pairs are valid. 
<DL>

<DT><B>-anchor <I>anchor</I></B> </DT>
<DD>Tells how to position the EPS item
relative to its X-Y coordinate. The default is <I>center</I>. </DD>

<DT><B>-background <I>color</I></B> </DT>
<DD>Sets
the background color of the EPS rectangle. </DD>

<DT><B>-borderwidth <I>pixels</I></B> </DT>
<DD>Sets the width
of the 3-D border around the outside edge of the item.  The <B>-relief</B> option
determines if the border is to be drawn.  The default is <I>0</I>. </DD>

<DT><B>-file <I>fileName</I></B>
</DT>
<DD>Specifies the name of the EPS file.  The first line of an EPS file must
start with "%!PS" and contain a "EPS" version specification.  The other
requirement is that there be a "%%BoundingBox:" entry which contains four
integers representing the lower-left and upper-right coordinates of the area
bounding the EPS. The default is <I>""</I>. </DD>

<DT><B>-font <I>fontName</I></B>  </DT>
<DD>Specifies the font of
the title. The default is <I>*-Helvetica-Bold-R-Normal-*-18-180-*</I>. </DD>

<DT><B>-foreground <I>color</I></B>
</DT>
<DD>Specifies the foreground color of the EPS rectangle.  The option matters
only when the <B>-stipple</B> option is set. The default is <I>white</I>. </DD>

<DT><B>-height <I>pixels</I></B>
</DT>
<DD>Specifies the height EPS item.  If <I>pixels</I> is <I>0</I>, then the height is determined
from the PostScript "BoundingBox:" entry in the EPS file. The default is
<I>0</I>. </DD>

<DT><B>-image <I>photo</I></B> </DT>
<DD>Specifies the name of a Tk photo image to be displayed as
in the item as a preview image.  This option overrides any preview specification
found in the EPS file. The default is <I>""</I>. </DD>

<DT><B>-justify <I>justify</I></B> </DT>
<DD>Specifies how the
title should be justified.  This matters only when the title contains more
than one line of text. <I>Justify</I> must be <I>left</I>, <I>right</I>, or <I>center</I>.  The default
is <I>center</I>. </DD>

<DT><B>-relief <I>relief</I></B> </DT>
<DD>Specifies the 3-D effect for the EPS item.  <I>Relief</I>
specifies how the item should appear relative to canvas;  for example,
<I>raised</I> means the item should appear to  protrude.  The default is <I>flat</I>. </DD>

<DT><B>-shadowcolor
<I>color</I></B> </DT>
<DD>Specifies the color of the drop shadow used for the title.  The option
with the <B>-shadowoffset</B> option control how the title's drop shadow appears.
The default is <I>grey</I>. </DD>

<DT><B>-shadowoffset <I>pixels</I></B> </DT>
<DD>Specifies the offset of the drop
shadow from the title's text. If <I>pixels</I> is <I>0</I>, no shadow will be seen. The
default is <I>0</I>. </DD>

<DT><B>-showimage <I>boolean</I></B> </DT>
<DD>Indicates whether to display the image preview
(if one exists),  or a simple rectangle.   The default is <I>yes</I>. </DD>

<DT><B>-stipple <I>bitmap</I></B>
</DT>
<DD>Specifies a bitmap to used to stipple the rectangle representing the EPS
item.  The default is <I>""</I>. </DD>

<DT><B>-title <I>string</I></B> </DT>
<DD>Sets the title of the EPS item.  If
<I>string</I> is <I>""</I>, then the title specified by the PostScript "Title:" entry
is used.  You can set the string a single space to display no title.  The
default is <I>""</I>. </DD>

<DT><B>-titleanchor <I>anchor</I></B> </DT>
<DD>Tells how to position the title within
EPS item. The default is <I>n</I>. </DD>

<DT><B>-titlecolor <I>color</I></B> </DT>
<DD>Specifies the color of the title.
  The default is <I>white</I>. </DD>

<DT><B>-titlerotate <I>degrees</I></B> </DT>
<DD>Sets the rotation of the title.
 <I>Degrees</I> is a real number representing the angle of rotation.   The title
is first rotated in space and then placed according to  the <B>-titleanchor</B>
position.  The default rotation is <I>0.0</I>. </DD>

<DT><B>-width <I>pixels</I></B> </DT>
<DD>Specifies the width EPS
item.  If <I>pixels</I> is <I>0</I>, then the width is determined from the PostScript
"BoundingBox:" entry in the EPS file. The default is <I>0</I>. <I>5i</I>. </DD>
</DL>

<H2><A NAME="sect5" HREF="#toc5">Example</A></H2>
The <B>graph</B>
command creates a new graph.   <BR>
<CODE># Create a new graph.  Plotting area is black.<BR>
graph .g -plotbackground black<BR>
</CODE><P>A new Tcl command <I>.g</I> is also created.  This command can be used to query
and modify the graph.  For example, to change the title of the graph to
"My Plot", you use the new command and the graph's <B>configure</B> operation. <BR>
<CODE># Change the title.<BR>
.g configure -title "My Plot"<BR>
</CODE><P>A graph has several components. To access a particular component you use
the component's name. For example, to add data elements, you use the new
command and the <B>element</B> component. <BR>
<CODE># Create a new element named "line1"<BR>
.g element create line1 \<BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;-xdata { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 } \<BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;-ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 <BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;155.85 166.60 175.38 }<BR>
</CODE><P>The element's X and Y coordinates are specified using lists of numbers. 
Alternately, BLT vectors could be used to hold the X-Y coordinates. <BR>
<CODE># Create two vectors and add them to the graph.<BR>
vector xVec yVec<BR>
xVec set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }<BR>
yVec set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85 <BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;166.60 175.38 }<BR>
.g element create line1 -xdata xVec -ydata yVec<BR>
</CODE><P>The advantage of using vectors is that when you modify one, the graph is
automatically redrawn to display the new values. <BR>
<CODE># Change the X-Y coordinates of the first point.<BR>
set xVec(0) 0.18<BR>
set yVec(0) 25.18<BR>
</CODE><P>An element named <I>line1</I> is now created in <I>.g</I>.  By default, the element's label
in the legend will be also <I>line1</I>. You can change the label, or specify no
legend entry, again using the element's <B>configure</B> operation. <BR>
<CODE># Don't display "line1" in the legend.<BR>
.g element configure line1 -label ""<BR>
</CODE><P>You can configure more than just the element's label.  An element has many
attributes such as symbol type and size, dashed or solid lines, colors,
line width, etc. <BR>
<CODE>.g element configure line1 -symbol square -color red \<BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;-dashes { 2 4 2 } -linewidth 2 -pixels 2c<BR>
</CODE><P>Four coordinate axes are automatically created: <I>x</I>, <I>x2</I>, <I>y</I>, and <I>y2</I>.  And by
default, elements are mapped onto the axes <I>x</I> and <I>y</I>.  This can be changed
with the <B>-mapx</B> and <B>-mapy</B> options. <BR>
<CODE># Map "line1" on the alternate Y-axis "y2".<BR>
.g element configure line1 -mapy y2<BR>
</CODE><P>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. <BR>
<CODE># Y-axis is log scale.<BR>
.g axis configure y -logscale yes<BR>
</CODE><P>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. <BR>
<CODE>.g axis configure x -min 1.0 -max 1.5<BR>
.g axis configure y -min 12.0 -max 55.15<BR>
</CODE><P>To zoom interactively, you link the axis <B>configure</B> operations with some
user interaction (such as pressing the mouse button), using the <B>bind</B> command.
 To convert between screen and graph coordinates, use the <B>invtransform</B>
operation. <BR>
<CODE># Click the button to set a new minimum <BR>
bind .g &lt;ButtonPress-1&gt; { <BR>
    %W axis configure x -min [%W axis invtransform x %x]<BR>
    %W axis configure x -min [%W axis invtransform x %y]<BR>
}<BR>
</CODE><P>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.
<BR>
<CODE># Reset the axes to autoscale again.<BR>
.g axis configure x -min {} -max {}<BR>
.g axis configure y -min {} -max {}<BR>
</CODE><P>By default, the legend is drawn in the right margin.  You can change this
or any legend configuration options using the <B>legend</B> component. <BR>
<CODE># Configure the legend font, color, and relief<BR>
.g legend configure -position left -relief raised \<BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;-font fixed -fg blue<BR>
</CODE><P>To prevent the legend from being displayed, turn on the <B>-hide</B> option. <BR>
<CODE># Don't display the legend.<BR>
.g legend configure -hide yes<BR>
</CODE><P>The <B>graph</B> widget 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, images, polygons, lines, or windows. Markers can
be used, for example, to mark or brush points.  In this example, is a text
marker that labels the data first point.  Markers are created using the
<B>marker</B> component. <BR>
<CODE># Create a label for the first data point of "line1".<BR>
.g marker create text -name first_marker -coords { 0.2 26.18 } \<BR>
<tt>&#32;</tt>&nbsp;<tt>&#32;</tt>&nbsp;-text "start" -anchor se -xoffset -10 -yoffset -10<BR>
</CODE><P>This creates a text marker named <I>first_marker</I>.  It will display the text
"start" near the coordinates of the first data point.  The <B>-anchor</B>, <B>-xoffset</B>,
and <B>-yoffset</B> options are used to display the marker above and to the left
of the data point, so that the data point isn't covered by the marker.  By
default, markers are drawn last, on top of data.  You can change this with
the <B>-under</B> option. <BR>
<CODE># Draw the label before elements are drawn.<BR>
.g marker configure first_marker -under yes<BR>
</CODE><P>You can add cross hairs or grid lines using the <B>crosshairs</B> and <B>grid</B> components.
<BR>
<CODE># Display both cross hairs and grid lines.<BR>
.g crosshairs configure -hide no -color red<BR>
.g grid configure -hide no -dashes { 2 2 }<BR>
</CODE><P>Finally, to get hardcopy of the graph, use the <B>postscript</B> component. <BR>
<CODE># Print the graph into file "file.ps"<BR>
.g postscript output file.ps -maxpect yes -decorations no<BR>
</CODE><P>This generates a file <I>file.ps</I> containing the encapsulated 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). 
<H2><A NAME="sect6" HREF="#toc6">Graph Operations</A></H2>

<DL>

<DT><I>pathName <B>axis <I>operation
</I></B></I>?<I>arg</I>?... </DT>
<DD>See the  <FONT SIZE=-1><B>AXIS COMPONENTS</B></FONT>
  section. </DD>

<DT><I>pathName <B>bar <I>elemName </I></B></I>?<I>option value</I>?...
</DT>
<DD>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. </DD>

<DT><I>pathName <B>cget</B></I> <I>option</I> </DT>
<DD>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>configure</B> operation. </DD>

<DT><I>pathName <B>configure </B></I>?<I>option value</I>?... </DT>
<DD>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. <blockquote></DD>

<DT><B>-background
<I>color</I></B> </DT>
<DD>Sets the background color. This includes the margins and legend, but
not the plotting area. </DD>

<DT><B>-borderwidth <I>pixels</I></B> </DT>
<DD>Sets the width of the 3-D border
around the outside edge of the widget.  The <B>-relief</B> option determines if
the border is to be drawn.  The default is <I>2</I>. </DD>

<DT><B>-bottommargin <I>pixels</I></B> </DT>
<DD>Specifies
the size of the margin below the X-coordinate axis.  If <I>pixels</I> is <I>0</I>, the
size of the margin is selected automatically. The default is <I>0</I>. </DD>

<DT><B>-bufferelements
<I>boolean</I></B> </DT>
<DD>Indicates whether an internal pixmap to buffer the display 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 <FONT SIZE=-1><B>SPEED TIPS</B></FONT>
  section. The default is <I>1</I>.
</DD>

<DT><B>-cursor <I>cursor</I></B> </DT>
<DD>Specifies the widget's cursor.  The default cursor is <I>crosshair</I>.
</DD>

<DT><B>-font <I>fontName</I></B>  </DT>
<DD>Specifies the font of the graph title. The default is <I>*-Helvetica-Bold-R-Normal-*-18-180-*</I>.
</DD>

<DT><B>-halo <I>pixels</I></B>  </DT>
<DD>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 <I>0.5i</I>. </DD>

<DT><B>-height
<I>pixels</I></B> </DT>
<DD>Specifies the requested height of widget.  The default is <I>4i</I>. </DD>

<DT><B>-invertxy
<I>boolean</I></B> </DT>
<DD>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 <I>0</I>. </DD>

<DT><B>-justify
<I>justify</I></B> </DT>
<DD>Specifies how the title should be justified.  This matters only
when the title contains more than one line of text. <I>Justify</I> must be <I>left</I>,
<I>right</I>, or <I>center</I>.  The default is <I>center</I>. </DD>

<DT><B>-leftmargin <I>pixels</I></B> </DT>
<DD>Sets the size
of the margin from the left edge of the window to  the Y-coordinate axis.
 If <I>pixels</I> is <I>0</I>, the size is calculated automatically.  The default is <I>0</I>.
</DD>

<DT><B>-plotbackground <I>color</I></B> </DT>
<DD>Specifies the background color of the plotting area.
 The default is <I>white</I>. </DD>

<DT><B>-plotborderwidth <I>pixels</I></B> </DT>
<DD>Sets the width of the 3-D border
around the plotting area.  The <B>-plotrelief</B> option determines if a border
is drawn.  The default is <I>2</I>. </DD>

<DT><B>-plotpadx <I>pad</I></B> </DT>
<DD>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 <I>8</I>. </DD>

<DT><B>-plotpady <I>pad</I></B> </DT>
<DD>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 <I>8</I>. </DD>

<DT><B>-plotrelief <I>relief</I></B> </DT>
<DD>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, <I>raised</I> means
the plot should appear to protrude from the graph, relative to the surface
of the graph.  The default is <I>sunken</I>. </DD>

<DT><B>-relief <I>relief</I></B> </DT>
<DD>Specifies the 3-D effect
for the graph widget.  <I>Relief</I> specifies how the graph should appear relative
to widget it is packed into; for example, <I>raised</I> means the graph should
appear to protrude.  The default is <I>flat</I>. </DD>

<DT><B>-rightmargin <I>pixels</I></B> </DT>
<DD>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. </DD>

<DT><B>-takefocus</B> <I>focus</I>  </DT>
<DD>Provides information used when
moving the focus from window to window via keyboard traversal (e.g., Tab
and Shift-Tab).  If <I>focus</I> is <I>0</I>, this means that this window should be skipped
entirely during keyboard traversal.  <I>1</I> 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
<I>""</I>. </DD>

<DT><B>-tile <I>image</I></B>  </DT>
<DD>Specifies a tiled background for the widget.  If <I>image</I> isn't
<I>""</I>, the background is tiled using <I>image</I>. Otherwise, the normal background
color is drawn (see the <B>-background</B> option).  <I>Image</I> must be an image created
using the Tk <B>image</B> command.  The default is <I>""</I>. </DD>

<DT><B>-title <I>text</I></B>  </DT>
<DD>Sets the title
to <I>text</I>. If <I>text</I> is <I>""</I>, no title will be displayed. </DD>

<DT><B>-topmargin <I>pixels</I></B> </DT>
<DD>Specifies
the size of the margin above the x2 axis.  If <I>pixels</I> is <I>0</I>, the margin size
is calculated automatically. </DD>

<DT><B>-width <I>pixels</I></B> </DT>
<DD>Specifies the requested width
of the widget.  The default is <I>5i</I>. </DD>
</DL>
</blockquote>

<DL>

<DT><I>pathName <B>crosshairs <I>operation </I></B></I>?<I>arg</I>? </DT>
<DD>See
the  <FONT SIZE=-1><B>CROSSHAIRS COMPONENT</B></FONT>
  section. </DD>

<DT><I>pathName <B>element <I>operation </I></B></I>?<I>arg</I>?... </DT>
<DD>See
the  <FONT SIZE=-1><B>ELEMENT COMPONENTS</B></FONT>
  section. </DD>

<DT><I>pathName <B>extents <I>item</I></B></I>  </DT>
<DD>Reports the size
of a particular items in the graph.  <I>Item</I> must be either <I>leftmargin</I>, <I>rightmargin</I>,
<I>topmargin</I>, <I>bottommargin</I>, <I>plotwidth</I>, or <I>plotheight</I>. </DD>

<DT><I>pathName <B>grid <I>operation
</I></B></I>?<I>arg</I>?... </DT>
<DD>See the  <FONT SIZE=-1><B>GRID COMPONENT</B></FONT>
  section. </DD>

<DT><I>pathName <B>invtransform <I>winX winY</I></B></I>
 </DT>
<DD>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 y graph coordinates. </DD>

<DT><I>pathName <B>inside <I>x y</I></B></I> </DT>
<DD>Returns
<I>1</I> is the designated screen coordinate (<I>x</I> and <I>y</I>) is inside the plotting
area and <I>0</I> otherwise. </DD>

<DT><I>pathName <B>legend <I>operation </I></B></I>?<I>arg</I>?... </DT>
<DD>See the  <FONT SIZE=-1><B>LEGEND COMPONENT</B></FONT>

 section. </DD>

<DT><I>pathName <B>line<B> operation arg</B></B></I>... </DT>
<DD>The operation is the same as <B>element</B>.
</DD>

<DT><I>pathName <B>marker <I>operation </I></B></I>?<I>arg</I>?... </DT>
<DD>See the  <FONT SIZE=-1><B>MARKER COMPONENTS</B></FONT>
  section. </DD>

<DT><I>pathName
<B>postscript <I>operation </I></B></I>?<I>arg</I>?... </DT>
<DD>See the  <FONT SIZE=-1><B>POSTSCRIPT COMPONENT</B></FONT>
  section. </DD>

<DT><I>pathName
<B>snap <I>photoName</I></B></I> </DT>
<DD>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. </DD>

<DT><I>pathName <B>transform <I>x y</I></B></I>  </DT>
<DD>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. </DD>

<DT><I>pathName
<B>xaxis <I>operation</I></B></I> ?<I>arg</I>?... </DT>
<DD></DD>

<DT><I>pathName <B>x2axis <I>operation</I></B></I> ?<I>arg</I>?...  </DT>
<DD></DD>

<DT><I>pathName <B>yaxis <I>operation</I></B></I>
?<I>arg</I>?...  </DT>
<DD></DD>

<DT><I>pathName <B>y2axis <I>operation</I></B></I> ?<I>arg</I>?...  </DT>
<DD>See the  <FONT SIZE=-1><B>AXIS COMPONENTS</B></FONT>
  section.
</DD>
</DL>

<H2><A NAME="sect7" HREF="#toc7">Graph Components</A></H2>
A graph is composed of several components: coordinate axes,
data elements, 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.
 
<H3><A NAME="sect8" HREF="#toc8">Axis Components</A></H3>
Four coordinate axes are automatically created: two X-coordinate
axes (<I>x</I> and <I>x2</I>) and two Y-coordinate axes (<I>y</I>, and <I>y2</I>).  By default, the axis
<I>x</I> is located in the bottom margin, <I>y</I> in the left margin, <I>x2</I> in the top
margin, and <I>y2</I> in the right margin. <P>
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.   <P>
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 plotted.  By default,
the minimum and maximum limits are determined from the data, but you can
reset either limit. <P>
You can create and use several axes. To create an axis,
invoke the axis component and its create operation. <BR>
<CODE># Create a new axis called "tempAxis"<BR>
.g axis create tempAxis<BR>
</CODE><P>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. <BR>
<CODE># Now map the tempAxis data to this axis.<BR>
.g element create "e1" -xdata $x -ydata $y -mapy tempAxis<BR>
</CODE><P>While you can create many axes, only four can be displayed simultaneously.
They are drawn in each of the margins surrounding the plotting area.  The
axes <I>x</I> and <I>y</I> are drawn in the bottom and left margins. The axes <I>x2</I> and <I>y2</I>
are drawn in top and right margins. Only <I>x</I> and <I>y</I> are shown by default. Note
that the axes can have different scales. <P>
To display a different axis, you
invoke one of the following components: <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. <BR>
<CODE># Display the axis tempAxis in the left margin.<BR>
.g yaxis use tempAxis<BR>
<P>
</CODE><P>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. <P>

<DL>

<DT><I>pathName <B>axis <B>cget <I>axisName
<I>option</I></I></B></B></I> </DT>
<DD>Returns the current value of the option given by <I>option</I> for <I>axisName</I>.
 <I>Option</I> may be any option described below for the axis <B>configure</B> operation.
</DD>

<DT><I>pathName <B>axis <B>configure <I>axisName </I></B></B></I>?<I>axisName</I>?... ?<I>option value</I>?... </DT>
<DD>Queries or modifies
the configuration options of <I>axisName</I>. Several axes can be changed.  If <I>option</I>
isn't specified, a list describing all the current options for <I>axisName</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 axis option <I>option</I> is set to <I>value</I>.  The following
options are valid for axes. <blockquote></DD>

<DT><B>-color <I>color</I></B> </DT>
<DD>Sets the color of the axis and tick
labels. The default is <I>black</I>. </DD>

<DT><B>-command <I>prefix</I></B> </DT>
<DD>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 <I>""</I> is returned, no label will appear next to the tick.  You can
get the standard tick labels again by setting <I>prefix</I> to <I>""</I>.  The default
is <I>""</I>. <P>
Please note that this procedure is invoked while the graph is redrawn.
You may query configuration options.  But do not them, because this can
have unexpected results. </DD>

<DT><B>-descending <I>boolean</I></B>  </DT>
<DD>Indicates whether the values
along the axis are monotonically increasing or decreasing.  If <I>boolean</I> is
true, the axis values will be decreasing.  The default is <I>0</I>. </DD>

<DT><B>-hide <I>boolean</I></B>
</DT>
<DD>Indicates whether the axis is displayed.  </DD>

<DT><B>-justify <I>justify</I></B> </DT>
<DD>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 <I>left</I>, <I>right</I>, or <I>center</I>.
 The default is <I>center</I>. </DD>

<DT><B>-limits <I>formatStr</I></B> </DT>
<DD>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 descriptions.  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 <I>""</I> is given as either description, then  the that limit will
not be displayed.  The default is <I>""</I>. </DD>

<DT><B>-linewidth <I>pixels</I></B> </DT>
<DD>Sets the width of
the axis and tick lines.  The default is <I>1</I> pixel. </DD>

<DT><B>-logscale <I>boolean</I></B> </DT>
<DD>Indicates
whether the scale of the axis is logarithmic or linear.  If <I>boolean</I> is true,
the axis is logarithmic.  The default scale is linear. </DD>

<DT><B>-loose <I>boolean</I></B> </DT>
<DD>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 <I>boolean</I>
is true, the axis range is "loose". The default is <I>0</I>. </DD>

<DT><B>-majorticks <I>majorList</I></B>
</DT>
<DD>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 <I>""</I>,  major ticks will be automatically computed. The default is <I>""</I>. </DD>

<DT><B>-max
<I>value</I></B> </DT>
<DD>Sets the maximum limit of <I>axisName</I>.  Any data point greater  than
<I>value</I> is not displayed.  If <I>value</I> is <I>""</I>,  the maximum limit is calculated
using the largest data value. The default is <I>""</I>. </DD>

<DT><B>-min <I>value</I></B> </DT>
<DD>Sets the minimum
limit of <I>axisName</I>. Any data point less than  <I>value</I> is not displayed.  If
<I>value</I> is <I>""</I>, the minimum limit is calculated using the smallest data value.
The default is <I>""</I>. </DD>

<DT><B>-minorticks <I>minorList</I></B> </DT>
<DD>Specifies where to display minor
axis ticks.  You can use this option to display minor ticks at non-uniform
intervals. <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 <I>""</I>, minor ticks will be automatically
computed. The default is <I>""</I>. </DD>

<DT><B>-rotate <I>theta</I></B> </DT>
<DD>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 <I>0.0</I> degrees. </DD>

<DT><B>-showticks
<I>boolean</I></B> </DT>
<DD>Indicates whether axis ticks should be drawn. If <I>boolean</I> is true,
ticks are drawn.  If false, only the axis line is drawn. The default is <I>1</I>.
</DD>

<DT><B>-stepsize <I>value</I></B> </DT>
<DD>Specifies the interval between major axis ticks.  If <I>value</I>
isn't a valid interval (must be less than the axis range),  the request
is ignored and the step size is automatically calculated. </DD>

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

<DT><B>-tickfont <I>fontName</I></B>  </DT>
<DD>Specifies the font for
axis tick labels. The default is <I>*-Courier-Bold-R-Normal-*-100-*</I>. </DD>

<DT><B>-ticklength <I>pixels</I></B>
</DT>
<DD>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 <I>0.1i</I>. </DD>

<DT><B>-title <I>text</I></B>
</DT>
<DD>Sets the title of the axis. If <I>text</I> is  <I>""</I>, no axis title will be displayed.
  </DD>

<DT><B>-titlecolor <I>color</I></B> </DT>
<DD>Sets the color of the axis title. The default is <I>black</I>.
</DD>

<DT><B>-titlefont <I>fontName</I></B>  </DT>
<DD>Specifies the font for axis title. The default is <I>*-Helvetica-Bold-R-Normal-*-14-140-*</I>.
</DD>
</DL>
<P>
Axis configuration options may be also be set by the <B>option</B> command.  The
resource class is <I>Axis</I>.  The resource names are the names of the axes (such
as <I>x</I> or <I>x2</I>). <BR>
<CODE>option add *Graph.Axis.Color  blue<BR>
option add *Graph.x.LogScale  true<BR>
option add *Graph.x2.LogScale false<BR>
</blockquote>

<DL>

<DT></CODE><P><I>pathName <B>axis <B>create <I>axisName </I></B></B></I>?<I>option value</I>?... </DT>
<DD>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. </DD>

<DT><I>pathName <B>axis <B>delete
</B></B></I>?<I>axisName</I>?... </DT>
<DD>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 elements. </DD>

<DT><I>pathName
<B>axis invtransform <I>axisName value</I></B></I> </DT>
<DD>Performs the inverse transformation, changing
the screen coordinate <I>value</I> to a graph coordinate, mapping the value mapped
to <I>axisName</I>.  Returns the graph coordinate. </DD>

<DT><I>pathName <B>axis limits <I>axisName</I></B></I>
</DT>
<DD>Returns a list of the minimum and maximum limits for <I>axisName</I>.  The order
of the list is <I>min max</I>. </DD>

<DT><I>pathName <B>axis names </B></I>?<I>pattern</I>?... </DT>
<DD>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. </DD>

<DT><I>pathName <B>axis transform <I>axisName value</I></B></I> </DT>
<DD>Transforms
the coordinate <I>value</I> to a screen coordinate by mapping the it to <I>axisName</I>.
 Returns the transformed screen coordinate. </DD>
</DL>
<P>
Only four axes can be displayed
simultaneously.  By default, they are <I>x</I>, <I>y</I>, <I>x2</I>, and <I>y2</I>.  You can swap in
a different axis with <B>use</B> operation of the special axis components: <B>xaxis</B>,
<B>x2axis</B>, <B>yaxis</B>, and <B>y2axis</B>. <BR>
<CODE>.g create axis temp<BR>
.g create axis time<BR>
...<BR>
.g xaxis use temp<BR>
.g yaxis use time<BR>
</CODE><P>Only the axes specified for use are displayed on the screen. <P>
The <B>xaxis</B>,
<B>x2axis</B>, <B>yaxis</B>, and <B>y2axis</B> components operate on an axis location rather
than a specific axis like the more general <B>axis</B> component does.  The <B>xaxis</B>
component manages the X-axis located in the bottom margin (whatever axis
that happens to be).  Likewise, <B>yaxis</B> uses the Y-axis in the left margin,
<B>x2axis</B> the top X-axis, and <B>y2axis</B> the right Y-axis. <P>
They implicitly control
the axis that is currently using to that location.  By default, <B>xaxis</B> uses
the <I>x</I> axis, <B>yaxis</B> uses <I>y</I>, <B>x2axis</B> uses <I>x2</I>, and <B>y2axis</B> uses <I>y2</I>.  These components
can be more convenient to use than always determining what axes are current
being displayed by the graph. <P>
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>. 
<DL>

<DT><I>pathName <I>axis <B>cget <I>option</I></B></I></I>
</DT>
<DD></DD>

<DT><I>pathName <I>axis <B>configure </B></I></I>?<I>option value</I>?... </DT>
<DD></DD>

<DT><I>pathName <I>axis<B> invtransform <I>value</I></B></I></I>
</DT>
<DD></DD>

<DT><I>pathName <I>axis <B>limits</B></I></I> </DT>
<DD></DD>

<DT><I>pathName <I>axis<B> transform <I>value</I></B></I></I> </DT>
<DD></DD>

<DT><I>pathName <I>axis<B> use </B></I></I>?<I>axisName</I>?
  </DT>
<DD>Designates the axis <I>axisName</I> is to be displayed at this location.  <I>AxisName</I>
can not be already in use at another location.   This command returns the
name of the axis currently using this location. </DD>
</DL>

<H3><A NAME="sect9" HREF="#toc9">Crosshairs Component</A></H3>
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 without redrawing the entire
graph. <P>
The following operations are available for cross hairs: 
<DL>

<DT><I>pathName
<B>crosshairs cget <I>option</I></B></I> </DT>
<DD>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. </DD>

<DT><I>pathName <B>crosshairs configure </B></I>?<I>option value</I>?...
  </DT>
<DD>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. <blockquote></DD>

<DT><B>-color <I>color</I></B>
 </DT>
<DD>Sets the color of the cross hairs.  The default is <I>black</I>. </DD>

<DT><B>-dashes <I>dashList</I></B>
</DT>
<DD>Sets the dash style of the cross hairs. <I>DashList</I> 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 <I>dashList</I> is <I>""</I>, the
cross hairs will be solid lines. </DD>

<DT><B>-hide <I>boolean</I></B> </DT>
<DD>Indicates whether cross hairs
are drawn. If <I>boolean</I> is true, cross hairs are not drawn.  The default is
<I>yes</I>. </DD>

<DT><B>-linewidth <I>pixels</I></B> </DT>
<DD>Set the width of the cross hair lines.  The default
is <I>1</I>. </DD>

<DT><B>-position <I>pos</I></B>  </DT>
<DD>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. </DD>
</DL>
<P>
Cross hairs configuration options may be
also be set by the <B>option</B> command.  The resource name and class are <I>crosshairs</I>
and <I>Crosshairs</I> respectively. <BR>
<CODE>option add *Graph.Crosshairs.LineWidth 2<BR>
option add *Graph.Crosshairs.Color     red<BR>
</blockquote>

<DL>

<DT></CODE><P><I>pathName <B>crosshairs off</B></I> </DT>
<DD>Turns off the cross hairs.  </DD>

<DT><I>pathName <B>crosshairs
on</B></I> </DT>
<DD>Turns on the display of the cross hairs. </DD>

<DT><I>pathName <B>crosshairs toggle</B></I> 
</DT>
<DD>Toggles the current state of the cross hairs, alternately mapping and unmapping
the cross hairs. </DD>
</DL>

<H3><A NAME="sect10" HREF="#toc10">Element Components</A></H3>
A data element represents a set of data.
 It contains x and y vectors containing the coordinates of the data points.
 Elements can be displayed with a symbol at each data point and lines connecting
the points.  Elements also control the appearance of the data, such as the
symbol type, line width, color etc. <P>
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.   <P>
The following
operations are available for elements. 
<DL>

<DT><I>pathName <B>element activate <I>elemName
</I></B></I>?<I>index</I>?... </DT>
<DD>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. </DD>

<DT><I>pathName <B>element cget <I>elemName
<I>option</I></I></B></I> </DT>
<DD>Returns the current value of the element configuration option given
by  <I>option</I>.  <I>Option</I> may be any of the options described below for the element
<B>configure</B> operation. </DD>

<DT><I>pathName <B>element closest <I>x y</I></B></I> <I>varName</I> ?<I>option value</I>?...
?<I>elemName</I>?... </DT>
<DD>Finds the data point 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, that must
not be hidden.  If no elements are specified, then all visible elements
are searched.  It returns via the array variable <I>varName</I> the name of the
closest element, the index of its closest point, and the graph coordinates
of the point. Returns <I>0</I>, if no data point within the threshold distance
can be found, otherwise <I>1</I> is returned.  The following <I>option</I>-<I>value</I> pairs
are available. <blockquote></DD>

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

<DT><B>-interpolate <I>boolean</I></B> </DT>
<DD>Indicates that both the data points
and interpolated points along the line segment formed should be considered.
 If <I>boolean</I>  is true, the closest line segment will be selected instead
of the closest point. If this option isn't specified, <I>boolean</I> defaults  to
<I>0</I>. </DD>
</DL>
</blockquote>

<DL>

<DT><I>pathName <B>element configure <I>elemName </I></B></I>?<I>elemName</I>... ?<I>option value</I>?... </DT>
<DD>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. <blockquote></DD>

<DT><B>-activepen <I>penName</I></B> </DT>
<DD>Specifies pen to use to draw active element.
 If <I>penName</I> is <I>""</I>, no active elements will be drawn.  The default is  <I>activeLine</I>.
</DD>

<DT><B>-color <I>color</I></B>  </DT>
<DD>Sets the color of the traces connecting the data points.  
</DD>

<DT><B>-dashes <I>dashList</I></B> </DT>
<DD>Sets the dash style of element line. <I>DashList</I> is a list
of up to 11 numbers that alternately represent the lengths of the dashes
and gaps on the element line.  Each number must be between 1 and 255.  If
<I>dashList</I> is <I>""</I>, the lines will be solid. </DD>

<DT><B>-data <I>coordList</I></B> </DT>
<DD>Specifies the X-Y
coordinates of the data.  <I>CoordList</I> is a list of numeric expressions representing
the X-Y coordinate pairs of each data point. </DD>

<DT><B>-fill <I>color</I></B>  </DT>
<DD>Sets the interior
color of symbols.  If <I>color</I> is <I>""</I>, then the interior of the symbol is transparent.
 If <I>color</I> is <I>defcolor</I>, then the color will be the same as the <B>-color</B> option.
 The default is <I>defcolor</I>. </DD>

<DT><B>-hide <I>boolean</I></B> </DT>
<DD>Indicates whether the element is
displayed.  The default is <I>no</I>. </DD>

<DT><B>-label <I>text</I></B> </DT>
<DD>Sets the element's label in the
legend.  If <I>text</I> is <I>""</I>, the element will have no entry in the legend. The
default label is the element's name. </DD>

<DT><B>-linewidth <I>pixels</I></B>  </DT>
<DD>Sets the width of
the connecting lines between data points.  If <I>pixels</I> is <I>0</I>, no connecting
lines will be drawn between symbols.  The default is <I>0</I>. </DD>

<DT><B>-mapx <I>xAxis</I></B> </DT>
<DD>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 <I>x</I>. </DD>

<DT><B>-mapy <I>yAxis</I></B> </DT>
<DD>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 <I>y</I>. </DD>

<DT><B>-offdash
<I>color</I></B> </DT>
<DD>Sets the color of the stripes when traces are dashed (see the <B>-dashes</B>
option).  If <I>color</I> is <I>""</I>, then the "off" pixels will represent gaps instead
of stripes.  If <I>color</I> is <I>defcolor</I>, then the color will be the same as the
<B>-color</B> option.  The default is <I>defcolor</I>. </DD>

<DT><B>-outline <I>color</I></B>  </DT>
<DD>Sets the color or
the outline around each symbol.  If <I>color</I> is <I>""</I>, then no outline is drawn.
If <I>color</I> is <I>defcolor</I>, then the color will be the same as the <B>-color</B> option.
 The default is <I>defcolor</I>. </DD>

<DT><B>-outlinewidth <I>pixels</I></B>  </DT>
<DD>Sets the width of the outline
bordering each symbol.  If <I>pixels</I> is <I>0</I>, no outline will be drawn. The default
is <I>1</I>. </DD>

<DT><B>-pixels <I>pixels</I></B> </DT>
<DD>Sets the size of symbols.  If <I>pixels</I> is <I>0</I>, no symbols
will be drawn.  The default is <I>0.125i</I>. </DD>

<DT><B>-scalesymbols <I>boolean</I></B>  </DT>
<DD>If <I>boolean</I> is
true, the size of the symbols drawn for <I>elemName</I> will change with scale
of the X-axis and Y-axis. At the time this option is set, the current ranges
of the axes are saved as the normalized scales (i.e scale factor is 1.0)
and the element is drawn at its designated size (see the <B>-pixels</B> option).
 As the scale of the axes change, the symbol will be scaled according to
the smaller of the X-axis and Y-axis scales.  If <I>boolean</I> is false, the element's
symbols are drawn at the designated size, regardless of axis scales.  The
default is <I>0</I>. </DD>

<DT><B>-smooth <I>smooth</I></B>  </DT>
<DD>Specifies how connecting line segments are
drawn between data points. <I>Smooth</I> can be either <I>linear</I>, <I>step</I>, <I>natural</I>, or
<I>quadratic</I>.  If <I>smooth</I> is <I>linear</I>, a single line segment is drawn, connecting
both data points. When <I>smooth</I> is <I>step</I>, two line segments are drawn. The first
is a horizontal line segment that steps the next X-coordinate.  The second
is a vertical line, moving to the next Y-coordinate.  Both <I>natural</I> and <I>quadratic</I>
generate multiple segments between data points.  If <I>natural</I>, the segments
are generated using a cubic spline.  If <I>quadratic</I>, a quadratic spline is
used.  The default is <I>linear</I>. </DD>

<DT><B>-styles <I>styleList</I></B>  </DT>
<DD>Specifies what pen to use
based on the range of weights given. <I>StyleList</I> is a list of style specifications.
Each style specification, in turn, is a list consisting of a pen name,
and optionally a minimum and maximum range.  Data points whose weight (see
the <B>-weight</B> option) falls in this range, are drawn with this pen.  If no
range is specified it defaults to the index of the pen in the list.  Note
that this affects only symbol attributes. Line attributes, such as line
width, dashes, etc. are ignored. </DD>

<DT><B>-symbol <I>symbol</I></B>  </DT>
<DD>Specifies the symbol for
data points.  <I>Symbol</I> can be either <I>square</I>, <I>circle</I>, <I>diamond</I>, <I>plus</I>, <I>cross</I>,
<I>splus</I>, <I>scross</I>, <I>triangle</I>, <I>""</I> (where no symbol is drawn), or a bitmap.  Bitmaps
are specified as "<I>source</I> ?<I>mask</I>?", where <I>source</I> is the name of the bitmap,
and <I>mask</I> is the bitmap's optional mask.  The default is <I>circle</I>. </DD>

<DT><B>-trace <I>direction</I></B>
 </DT>
<DD>Indicates whether connecting lines between data points (whose X-coordinate
values are either increasing or decreasing) are drawn.   <I>Direction</I> must
be <I>increasing</I>, <I>decreasing</I>, or <I>both</I>.  For example, if <I>direction</I> is <I>increasing</I>,
connecting lines will be drawn only between those data points where X-coordinate
values are monotonically increasing.  If <I>direction</I> is <I>both</I>, connecting lines
will be draw between all data points.  The default is <I>both</I>. </DD>

<DT><B>-weights <I>wVec</I></B>
 </DT>
<DD>Specifies the weights of the individual data points.  This,  with the list
pen styles (see the <B>-styles</B> option), controls how data points are drawn.
 <I>WVec</I> is the name of a BLT vector or a list of numeric expressions representing
the weights for each data point. </DD>

<DT><B>-xdata <I>xVec</I></B>  </DT>
<DD>Specifies the X-coordinates
of the data.  <I>XVec</I> is the name of a BLT vector or a list of numeric expressions.
</DD>

<DT><B>-ydata <I>yVec</I></B>  </DT>
<DD>Specifies the Y-coordinates of the data.  <I>YVec</I> is the name of
a BLT vector or a list of numeric expressions. </DD>
</DL>
<P>
Element configuration options
may also be set by the <B>option</B> command.  The resource class is <I>Element</I>. The
resource name is the name of the element. <BR>
<CODE>option add *Graph.Element.symbol line<BR>
option add *Graph.e1.symbol line<BR>
</blockquote>

<DL>

<DT></CODE><P><I>pathName <B>element create <I>elemName</I></B></I> ?<I>option value</I>?... </DT>
<DD>Creates a new element <I>elemName</I>.
 It's an error is an element <I>elemName</I> already exists.  If additional arguments
are present, they specify options valid for  the element <B>configure</B> operation.
</DD>

<DT><I>pathName <B>element deactivate <I>elemName</I></B></I> ?<I>elemName</I>?... </DT>
<DD>Deactivates all the elements
matching <I>pattern</I>. Elements whose names match any of the patterns given are
redrawn using their normal colors. </DD>

<DT><I>pathName <B>element delete</B></I> ?<I>elemName</I>?... </DT>
<DD>Deletes
all the named elements.  The graph is automatically redrawn. </DD>

<DT><I>pathName <B>element
exists <I>elemName</I></B></I> </DT>
<DD>Returns <I>1</I> if an element <I>elemName</I> currently exists and <I>0</I>
otherwise. </DD>

<DT><I>pathName <B>element names </B></I>?<I>pattern</I>?...   </DT>
<DD>Returns the elements matching
one or more pattern.  If no <I>pattern</I> is given, the names of all elements
is returned. </DD>

<DT><I>pathName <B>element show</B></I> ?<I>nameList</I>?   </DT>
<DD>Queries or modifies the
element display list.  The element display 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
display list is returned. </DD>

<DT><I>pathName <B>element type</B></I> <I>elemName</I> </DT>
<DD>Returns the type
of <I>elemName</I>.  If the element is a bar element, the commands returns the
string <I>"bar"</I>, otherwise it returns <I>"line"</I>. </DD>
</DL>

<H3><A NAME="sect11" HREF="#toc11"></CODE><P>Grid Component</A></H3>
Grid lines extend
from the major and minor ticks of each axis horizontally or vertically
across the plotting area.  The following operations are available for grid
lines. 
<DL>

<DT><I>pathName <B>grid cget <I>option</I></B></I> </DT>
<DD>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. </DD>

<DT><I>pathName <B>grid configure</B></I> ?<I>option
value</I>?... </DT>
<DD>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 following options are valid for grid lines. <blockquote></DD>

<DT><B>-color <I>color</I></B>  </DT>
<DD>Sets the color
of the grid lines.  The default is <I>black</I>. </DD>

<DT><B>-dashes <I>dashList</I></B> </DT>
<DD>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 <I>""</I>, the grid will be solid lines.
</DD>

<DT><B>-hide <I>boolean</I></B> </DT>
<DD>Indicates whether the grid should be drawn. If <I>boolean</I> is true,
grid lines are not shown. The default is <I>yes</I>. </DD>

<DT><B>-linewidth <I>pixels</I></B> </DT>
<DD>Sets the width
of grid lines.  The default width is <I>1</I>. </DD>

<DT><B>-mapx <I>xAxis</I></B> </DT>
<DD>Specifies the X-axis to
display grid lines.  <I>XAxis</I> must be the name of an axis.  The default is <I>x</I>.
</DD>

<DT><B>-mapy <I>yAxis</I></B> </DT>
<DD>Specifies the Y-axis to display grid lines.  <I>YAxis</I> must be the
name of an axis. The default is <I>y</I>. </DD>

<DT><B>-minor <I>boolean</I></B> </DT>
<DD>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 <I>1</I>. </DD>
</DL>
<P>
</blockquote>

<H2><A NAME="sect12" HREF="#toc12">Speed Tips</A></H2>
There may be
cases where the graph 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. 
<UL>
&#183;<LI>Try to minimize the number of data points.  The more data points
the looked at, the more work the graph must do. </LI>&#183;<LI>If your data is generated
as floating point values, the time required to convert the data values
to and from ASCII strings can be significant, especially when there any
many data points.  You can avoid the redundant string-to-decimal conversions
using the C API to BLT vectors. </LI>&#183;<LI>Data elements without symbols are drawn
faster than with symbols. Set the data element's <B>-symbol</B> option to <I>none</I>.  If
you need to draw symbols, try using the simple symbols such as <I>splus</I> and
<I>scross</I>. </LI>&#183;<LI>Don't stipple or dash the element.  Solid lines are much faster. </LI>&#183;<LI>If
you update data elements frequently, try turning off the widget's <B>-bufferelements</B>
option.  When the graph is first displayed, it draws data elements into
an internal pixmap.  The pixmap acts as a cache, so that when the graph
needs to be redrawn again, and the data elements or coordinate axes haven't
changed, the pixmap is simply copied to the screen.  This is especially
useful when you are using markers to highlight points and regions on the
graph.  But if the graph is updated frequently, changing either the element
data or coordinate axes, the buffering becomes redundant. </LI>
</UL>

<H2><A NAME="sect13" HREF="#toc13">Limitations</A></H2>
Auto-scale
routines do not use requested min/max limits as boundaries when the axis
is logarithmically scaled. <P>
The PostScript output generated for polygons
with more than 1500 points may exceed the limits of some printers (See
PostScript Language Reference Manual, page 568).  The work-around is to break
the polygon into separate pieces. 
<H2><A NAME="sect14" HREF="#toc14">Future Incompatibility</A></H2>
The <B>-mapped</B> options
are obsoleted and will be removed.  You can achieve the same results using
the <B>-hide</B> option instead. <BR>
<CODE># Works for now.<BR>
.g legend configure -mapped no<BR>
<P>
# Instead use this.<BR>
.g legend configure -hide yes    <BR>

<H2><A NAME="sect15" HREF="#toc15"></CODE><P>Keywords</A></H2>
graph, widget <P>

<HR><P>
<A NAME="toc"><B>Table of Contents</B></A><P>
<UL>
<LI><A NAME="toc0" HREF="#sect0">Name</A></LI>
<LI><A NAME="toc1" HREF="#sect1">Synopsis</A></LI>
<LI><A NAME="toc2" HREF="#sect2">Description</A></LI>
<LI><A NAME="toc3" HREF="#sect3">Example</A></LI>
<LI><A NAME="toc4" HREF="#sect4">Syntax</A></LI>
<LI><A NAME="toc5" HREF="#sect5">Example</A></LI>
<LI><A NAME="toc6" HREF="#sect6">Graph Operations</A></LI>
<LI><A NAME="toc7" HREF="#sect7">Graph Components</A></LI>
<UL>
<LI><A NAME="toc8" HREF="#sect8">Axis Components</A></LI>
<LI><A NAME="toc9" HREF="#sect9">Crosshairs Component</A></LI>
<LI><A NAME="toc10" HREF="#sect10">Element Components</A></LI>
<LI><A NAME="toc11" HREF="#sect11">Grid Component</A></LI>
</UL>
<LI><A NAME="toc12" HREF="#sect12">Speed Tips</A></LI>
<LI><A NAME="toc13" HREF="#sect13">Limitations</A></LI>
<LI><A NAME="toc14" HREF="#sect14">Future Incompatibility</A></LI>
<LI><A NAME="toc15" HREF="#sect15">Keywords</A></LI>
</UL>
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