NAME
eps - Encapsulated PostScript canvas item.
SYNOPSIS
canvas create eps x y ?option value?...
_________________________________________________________________
DESCRIPTION
The eps canvas item lets you place encapulated 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 hexidecimal
preview, or 2) a Tk photo image. When the canvas gener
ates 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.
EXAMPLE
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.
Normally, you would have to resort to an external tool or
write your own PostScript program. The eps canvas item
lets you do this through Tk's canvas widget. An eps item
displays an image (or rectangle) representing the encapsu
lated PostScript file. It also scales and translates the
EPS file when the canvas is printed.
SYNTAX
canvas create eps x y ?option value?...
The eps item creates a new canvas item. Canvas is the name
of a canvas widget. You must supply the X-Y coordinate of
the new eps item. How the coordinate is exactly inter
pretered is controlled by the -anchor option (see below).
Additional options may be specified on the command line to
configure aspects of the eps item such as its color, stip
ple, and font. The following option and value pairs are
valid.
-anchor anchor
Tells how to position the EPS item relative to its
X-Y coordinate. The default is center.
-background color
Sets the background color of the EPS rectangle.
Sets the width of the 3-D border around the outside
edge of the item. The -relief option determines if
the border is to be drawn. The default is 0.
-file fileName
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 "".
-font fontName
Specifies the font of the title. The default is
*-Helvetica-Bold-R-Normal-*-18-180-*.
-foreground color
Specifies the foreground color of the EPS rectan
gle. The option matters only when the -stipple
option is set. The default is white.
-height pixels
Specifies the height EPS item. If pixels is 0,
then the height is determined from the PostScript
"BoundingBox:" entry in the EPS file. The default
is 0.
-image photo
Specifies the name of a Tk photo image to be dis
played as in the item as a preview image. This
option overrides any preview specification found in
the EPS file. The default is "".
-justify justify
Specifies how the title should be justified. This
matters only when the title contains more than one
line of text. Justify must be left, right, or cen
ter. The default is center.
-relief relief
Specifies the 3-D effect for the EPS item. Relief
specifies how the item should appear relative to
canvas; for example, raised means the item should
appear to protrude. The default is flat.
-shadowcolor color
Specifies the color of the drop shadow used for the
title. The option with the -shadowoffset option
control how the title's drop shadow appears. The
default is grey.
Specifies the offset of the drop shadow from the
title's text. If pixels is 0, no shadow will be
seen. The default is 0.
-showimage boolean
Indicates whether to display the image preview (if
one exists), or a simple rectangle. The default is
yes.
-stipple bitmap
Specifies a bitmap to used to stipple the rectangle
representing the EPS item. The default is "".
-title string
Sets the title of the EPS item. If string is "",
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 "".
-titleanchor anchor
Tells how to position the title within EPS item.
The default is n.
-titlecolor color
Specifies the color of the title. The default is
white.
-titlerotate degrees
Sets the rotation of the title. Degrees is a real
number representing the angle of rotation. The
title is first rotated in space and then placed
according to the -titleanchor position. The
default rotation is 0.0.
-width pixels
Specifies the width EPS item. If pixels is 0, then
the width is determined from the PostScript "Bound
ingBox:" entry in the EPS file. The default is 0.
5i.
EXAMPLE
The graph command creates a new graph.
# Create a new graph. Plotting area is black.
graph .g -plotbackground black
A new Tcl command .g 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 configure operation.
# Change the title.
.g configure -title "My Plot"
component you use the component's name. For example, to
add data elements, you use the new command and the element
component.
# Create a new element named "line1"
.g element create line1 \
-xdata { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 } \
-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 and 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 graph.
vector xVec yVec
xVec set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
yVec set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
166.60 175.38 }
.g element create line1 -xdata xVec -ydata yVec
The advantage of using vectors is that when you modify
one, the graph is automatically redrawn to display the new
values.
# Change the X-Y coordinates of the first point.
set xVec(0) 0.18
set yVec(0) 25.18
An element named line1 is now created in .g. By default,
the element's label in the legend will be also line1. You
can change the label, or specify no legend entry, again
using the element's configure operation.
# Don't display "line1" in the legend.
.g element configure line1 -label ""
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.
.g element configure line1 -symbol square -color red \
-dashes { 2 4 2 } -linewidth 2 -pixels 2c
Four coordinate axes are automatically created: x, x2, y,
and y2. And by default, elements are mapped onto the axes
x and y. This can be changed with the -mapx and -mapy
options.
# Map "line1" on the alternate Y-axis "y2".
.g element configure line1 -mapy y2
Axes can be configured in many ways too. For example, you
the axis component.
# Y-axis is log scale.
.g axis configure y -logscale yes
One important way axes are used is to zoom in on a partic
ular data region. Zooming is done by simply specifying
new axis limits using the -min and -max configuration
options.
.g axis configure x -min 1.0 -max 1.5
.g axis configure y -min 12.0 -max 55.15
To zoom interactively, you link the axis configure opera
tions with some user interaction (such as pressing the
mouse button), using the bind command. To convert between
screen and graph coordinates, use the invtransform opera
tion.
# Click the button to set a new minimum
bind .g <ButtonPress-1> {
%W axis configure x -min [%W axis invtransform x %x]
%W axis configure x -min [%W axis invtransform x %y]
}
By default, the limits of the axis are determined from
data values. To reset back to the default limits, set the
-min and -max options to the empty value.
# Reset the axes to autoscale again.
.g axis configure x -min {} -max {}
.g axis configure y -min {} -max {}
By default, the legend is drawn in the right margin. You
can change this or any legend configuration options using
the legend component.
# Configure the legend font, color, and relief
.g legend configure -position left -relief raised \
-font fixed -fg blue
To prevent the legend from being displayed, turn on the
-hide option.
# Don't display the legend.
.g legend configure -hide yes
The graph 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
# Create a label for the first data point of "line1".
.g marker create text -name first_marker -coords { 0.2 26.18 } \
-text "start" -anchor se -xoffset -10 -yoffset -10
This creates a text marker named first_marker. It will
display the text "start" near the coordinates of the first
data point. The -anchor, -xoffset, and -yoffset 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 -under option.
# Draw the label before elements are drawn.
.g marker configure first_marker -under yes
You can add cross hairs or grid lines using the crosshairs
and grid components.
# Display both cross hairs and grid lines.
.g crosshairs configure -hide no -color red
.g grid configure -hide no -dashes { 2 2 }
Finally, to get hardcopy of the graph, use the postscript
component.
# Print the graph into file "file.ps"
.g postscript output file.ps -maxpect yes -decorations no
This generates a file file.ps containing the encapsulated
PostScript of the graph. The option -maxpect says to
scale the plot to the size of the page. Turning off the
-decorations option denotes that no borders or color back
grounds should be drawn (i.e. the background of the mar
gins, legend, and plotting area will be white).
GRAPH OPERATIONS
pathName axis operation ?arg?...
See the AXIS COMPONENTS section.
pathName bar elemName ?option value?...
Creates a new barchart element elemName. It's an
error if an element elemName already exists. See
the manual for barchart for details about what
option and value pairs are valid.
pathName cget option
Returns the current value of the configuration
option given by option. Option may be any option
described below for the configure operation.
pathName configure ?option value?...
Queries or modifies the configuration options of
describing the current options for pathName is
returned. If option is specified, but not value,
then a list describing option is returned. If one
or more option and value pairs are specified, then
for each pair, the option option is set to value.
The following options are valid.
-background color
Sets the background color. This includes the
margins and legend, but not the plotting
area.
-borderwidth pixels
Sets the width of the 3-D border around the
outside edge of the widget. The -relief
option determines if the border is to be
drawn. The default is 2.
-bottommargin pixels
Specifies the size of the margin below the
X-coordinate axis. If pixels is 0, the size
of the margin is selected automatically.
The default is 0.
-bufferelements boolean
Indicates whether an internal pixmap to
buffer the display of data elements should
be used. If boolean is true, data elements
are drawn to an internal pixmap. This
option is especially useful when the graph
is redrawn frequently while the remains data
unchanged (for example, moving a marker
across the plot). See the SPEED TIPS sec
tion. The default is 1.
-cursor cursor
Specifies the widget's cursor. The default
cursor is crosshair.
-font fontName
Specifies the font of the graph title. The
default is *-Helvetica-Bold-R-Nor
mal-*-18-180-*.
-halo pixels
Specifies a maximum distance to consider
when searching for the closest data point
(see the element's closest operation below).
Data points further than pixels away are
ignored. The default is 0.5i.
-height pixels
Specifies the requested height of widget.
-invertxy boolean
Indicates whether the placement X-axis and
Y-axis should be inverted. If boolean is
true, the X and Y axes are swapped. The
default is 0.
-justify justify
Specifies how the title should be justified.
This matters only when the title contains
more than one line of text. Justify must be
left, right, or center. The default is cen
ter.
-leftmargin pixels
Sets the size of the margin from the left
edge of the window to the Y-coordinate axis.
If pixels is 0, the size is calculated auto
matically. The default is 0.
-plotbackground color
Specifies the background color of the plot
ting area. The default is white.
-plotborderwidth pixels
Sets the width of the 3-D border around the
plotting area. The -plotrelief option
determines if a border is drawn. The
default is 2.
-plotpadx pad
Sets the amount of padding to be added to
the left and right sides of the plotting
area. Pad can be a list of one or two
screen distances. If pad has two elements,
the left side of the plotting area entry is
padded by the first distance and the right
side by the second. If pad is just one dis
tance, both the left and right sides are
padded evenly. The default is 8.
-plotpady pad
Sets the amount of padding to be added to
the top and bottom of the plotting area.
Pad can be a list of one or two screen dis
tances. If pad has two elements, the top of
the plotting area is padded by the first
distance and the bottom by the second. If
pad is just one distance, both the top and
bottom are padded evenly. The default is 8.
-plotrelief relief
Specifies the 3-D effect for the plotting
the plotting area should appear relative to
rest of the graph; for example, raised means
the plot should appear to protrude from the
graph, relative to the surface of the graph.
The default is sunken.
-relief relief
Specifies the 3-D effect for the graph wid
get. Relief specifies how the graph should
appear relative to widget it is packed into;
for example, raised means the graph should
appear to protrude. The default is flat.
-rightmargin pixels
Sets the size of margin from the plotting
area to the right edge of the window. By
default, the legend is drawn in this margin.
If pixels is than 1, the margin size is
selected automatically.
-takefocus focus
Provides information used when moving the
focus from window to window via keyboard
traversal (e.g., Tab and Shift-Tab). If
focus is 0, this means that this window
should be skipped entirely during keyboard
traversal. 1 means that the this window
should always receive the input focus. An
empty value means that the traversal scripts
make the decision whether to focus on the
window. The default is "".
-tile image
Specifies a tiled background for the widget.
If image isn't "", the background is tiled
using image. Otherwise, the normal back
ground color is drawn (see the -background
option). Image must be an image created
using the Tk image command. The default is
"".
-title text
Sets the title to text. If text is "", no
title will be displayed.
-topmargin pixels
Specifies the size of the margin above the
x2 axis. If pixels is 0, the margin size is
calculated automatically.
-width pixels
Specifies the requested width of the widget.
The default is 5i.
See the CROSSHAIRS COMPONENT section.
pathName element operation ?arg?...
See the ELEMENT COMPONENTS section.
pathName extents item
Reports the size of a particular items in the
graph. Item must be either leftmargin, rightmar
gin, topmargin, bottommargin, plotwidth, or
plotheight.
pathName grid operation ?arg?...
See the GRID COMPONENT section.
pathName invtransform winX winY
Performs an inverse coordinate transformation, map
ping 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.
pathName inside x y
Returns 1 is the designated screen coordinate (x
and y) is inside the plotting area and 0 otherwise.
pathName legend operation ?arg?...
See the LEGEND COMPONENT section.
pathName line operation arg...
The operation is the same as element.
pathName marker operation ?arg?...
See the MARKER COMPONENTS section.
pathName postscript operation ?arg?...
See the POSTSCRIPT COMPONENT section.
pathName snap photoName
Takes a snapshot of the graph and stores the con
tents in the photo image photoName. PhotoName is
the name of a Tk photo image that must already
exist.
pathName transform x y
Performs a coordinate transformation, mapping graph
coordinates to window coordinates, using the stan
dard X-axis and Y-axis. Returns a list containing
the X-Y screen coordinates.
pathName xaxis operation ?arg?...
pathName x2axis operation ?arg?...
pathName y2axis operation ?arg?...
See the AXIS COMPONENTS section.
GRAPH COMPONENTS
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 par
titioned, where each component has its own configuration
options and operations that specifically control that
aspect or part of the graph.
AXIS COMPONENTS
Four coordinate axes are automatically created: two
X-coordinate axes (x and x2) and two Y-coordinate axes (y,
and y2). By default, the axis x is located in the bottom
margin, y in the left margin, x2 in the top margin, and y2
in the right margin.
An axis consists of the axis line, title, major and minor
ticks, and tick labels. Major ticks are drawn at uniform
intervals along the axis. Each tick is labeled with its
coordinate value. Minor ticks are drawn at uniform inter
vals within major ticks.
The range of the axis controls what region of data is
plotted. Data points outside the minimum and maximum lim
its of the axis are not plotted. 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 "tempAxis"
.g axis create tempAxis
You map data elements to an axis using the element's -mapy
and -mapx configuration options. They specify the coordi
nate axes an element is mapped onto.
# Now map the tempAxis data to this axis.
.g element create "e1" -xdata $x -ydata $y -mapy tempAxis
While you can create many axes, only four can be displayed
simultaneously. They are drawn in each of the margins sur
rounding the plotting area. The axes x and y are drawn in
the bottom and left margins. The axes x2 and y2 are drawn
in top and right margins. Only x and y are shown by
default. Note that the axes can have different scales.
To display a different axis, you invoke one of the
The use operation designates the axis to be drawn in the
corresponding margin: xaxis in the bottom, yaxis in the
left, x2axis in the top, and y2axis in the right.
# Display the axis tempAxis in the left margin.
.g yaxis use tempAxis
You can configure axes in many ways. The axis scale can be
linear or logarithmic. The values along the axis can
either monotonically increase or decrease. If you need
custom tick labels, you can specify a Tcl procedure to
format the label any way you wish. You can control how
ticks are drawn, by changing the major tick interval or
the number of minor ticks. You can define non-uniform
tick intervals, such as for time-series plots.
pathName axis cget axisName option
Returns the current value of the option given by
option for axisName. Option may be any option
described below for the axis configure operation.
pathName axis configure axisName ?axisName?... ?option
value?...
Queries or modifies the configuration options of
axisName. Several axes can be changed. If option
isn't specified, a list describing all the current
options for axisName is returned. If option is
specified, but not value, then a list describing
option is returned. If one or more option and
value pairs are specified, then for each pair, the
axis option option is set to value. The following
options are valid for axes.
-color color
Sets the color of the axis and tick labels.
The default is black.
-command prefix
Specifies a Tcl command to be invoked when
formatting the axis tick labels. Prefix is a
string containing the name of a Tcl proc and
any extra arguments for the procedure. This
command is invoked for each major tick on
the axis. Two additional arguments are
passed to the procedure: the pathname of the
widget and the current the numeric value of
the tick. The procedure returns the format
ted tick label. If "" is returned, no label
will appear next to the tick. You can get
the standard tick labels again by setting
prefix to "". The default is "".
while the graph is redrawn. You may query
configuration options. But do not them,
because this can have unexpected results.
-descending boolean
Indicates whether the values along the axis
are monotonically increasing or decreasing.
If boolean is true, the axis values will be
decreasing. The default is 0.
-hide boolean
Indicates whether the axis is displayed.
-justify justify
Specifies how the axis title should be jus
tified. This matters only when the axis
title contains more than one line of text.
Justify must be left, right, or center. The
default is center.
-limits formatStr
Specifies a printf-like description to for
mat the minimum and maximum limits of the
axis. The limits are displayed at the
top/bottom or left/right sides of the plot
ting area. FormatStr 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 "" is given as either description, then
the that limit will not be displayed. The
default is "".
-linewidth pixels
Sets the width of the axis and tick lines.
The default is 1 pixel.
-logscale boolean
Indicates whether the scale of the axis is
logarithmic or linear. If boolean is true,
the axis is logarithmic. The default scale
is linear.
-loose boolean
Indicates whether the limits of the axis
should fit the data points tightly, at the
outermost data points, or loosely, at the
outer tick intervals. This is relevant only
when the axis limit is automatically calcu
lated. If boolean is true, the axis range
is "loose". The default is 0.
Specifies where to display major axis ticks.
You can use this option to display ticks at
non-uniform intervals. MajorList is a list
of axis coordinates designating the location
of major ticks. No minor ticks are drawn.
If majorList is "", major ticks will be
automatically computed. The default is "".
-max value
Sets the maximum limit of axisName. Any
data point greater than value is not dis
played. If value is "", the maximum limit
is calculated using the largest data value.
The default is "".
-min value
Sets the minimum limit of axisName. Any data
point less than value is not displayed. If
value is "", the minimum limit is calculated
using the smallest data value. The default
is "".
-minorticks minorList
Specifies where to display minor axis ticks.
You can use this option to display minor
ticks at non-uniform intervals. MinorList is
a list of real values, ranging from 0.0 to
1.0, designating the placement of a minor
tick. No minor ticks are drawn if the
-majortick option is also set. If minorList
is "", minor ticks will be automatically
computed. The default is "".
-rotate theta
Specifies the how many degrees to rotate the
axis tick labels. Theta is a real value
representing the number of degrees to rotate
the tick labels. The default is 0.0
degrees.
-showticks boolean
Indicates whether axis ticks should be
drawn. If boolean is true, ticks are drawn.
If false, only the axis line is drawn. The
default is 1.
-stepsize value
Specifies the interval between major axis
ticks. If value isn't a valid interval
(must be less than the axis range), the
request is ignored and the step size is
automatically calculated.
Indicates how many minor axis ticks are to
be drawn. For example, if number is two,
only one minor tick is drawn. If number is
one, no minor ticks are displayed. The
default is 2.
-tickfont fontName
Specifies the font for axis tick labels. The
default is *-Courier-Bold-R-Normal-*-100-*.
-ticklength pixels
Sets the length of major and minor ticks
(minor ticks are half the length of major
ticks). If pixels is less than zero, the
axis will be inverted with ticks drawn
pointing towards the plot. The default is
0.1i.
-title text
Sets the title of the axis. If text is "",
no axis title will be displayed.
-titlecolor color
Sets the color of the axis title. The
default is black.
-titlefont fontName
Specifies the font for axis title. The
default is *-Helvetica-Bold-R-Nor
mal-*-14-140-*.
Axis configuration options may be also be set by
the option command. The resource class is Axis.
The resource names are the names of the axes (such
as x or x2).
option add *Graph.Axis.Color blue
option add *Graph.x.LogScale true
option add *Graph.x2.LogScale false
pathName axis create axisName ?option value?...
Creates a new axis by the name axisName. No axis
by the same name can already exist. Option and
value are described in above in the axis configure
operation.
pathName axis delete ?axisName?...
Deletes the named axes. An axis is not really
deleted until it is not longer in use, so it's safe
to delete axes mapped to elements.
Performs the inverse transformation, changing the
screen coordinate value to a graph coordinate, map
ping the value mapped to axisName. Returns the
graph coordinate.
pathName axis limits axisName
Returns a list of the minimum and maximum limits
for axisName. The order of the list is min max.
pathName axis names ?pattern?...
Returns a list of axes matching zero or more pat
terns. If no pattern argument is give, the names
of all axes are returned.
pathName axis transform axisName value
Transforms the coordinate value to a screen coordi
nate by mapping the it to axisName. Returns the
transformed screen coordinate.
Only four axes can be displayed simultaneously. By
default, they are x, y, x2, and y2. You can swap in a
different axis with use operation of the special axis com
ponents: xaxis, x2axis, yaxis, and y2axis.
.g create axis temp
.g create axis time
...
.g xaxis use temp
.g yaxis use time
Only the axes specified for use are displayed on the
screen.
The xaxis, x2axis, yaxis, and y2axis components operate on
an axis location rather than a specific axis like the more
general axis component does. The xaxis component manages
the X-axis located in the bottom margin (whatever axis
that happens to be). Likewise, yaxis uses the Y-axis in
the left margin, x2axis the top X-axis, and y2axis the
right Y-axis.
They implicitly control the axis that is currently using
to that location. By default, xaxis uses the x axis,
yaxis uses y, x2axis uses x2, and y2axis uses y2. These
components can be more convenient to use than always
determining what axes are current being displayed by the
graph.
The following operations are available for axes. They mir
ror exactly the operations of the axis component. The
axis argument must be xaxis, x2axis, yaxis, or y2axis.
pathName axis configure ?option value?...
pathName axis invtransform value
pathName axis limits
pathName axis transform value
pathName axis use ?axisName?
Designates the axis axisName is to be displayed at
this location. AxisName can not be already in use
at another location. This command returns the name
of the axis currently using this location.
CROSSHAIRS COMPONENT
Cross hairs consist of two intersecting lines (one verti
cal and one horizontal) drawn completely across the plot
ting area. They are used to position the mouse in rela
tion 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.
The following operations are available for cross hairs:
pathName crosshairs cget option
Returns the current value of the cross hairs con
figuration option given by option. Option may be
any option described below for the cross hairs con
figure operation.
pathName crosshairs configure ?option value?...
Queries or modifies the configuration options of
the cross hairs. If option isn't specified, a list
describing all the current options for the cross
hairs is returned. If option is specified, but not
value, then a list describing option is returned.
If one or more option and value pairs are speci
fied, then for each pair, the cross hairs option
option is set to value. The following options are
available for cross hairs.
-color color
Sets the color of the cross hairs. The
default is black.
-dashes dashList
Sets the dash style of the cross hairs.
DashList is a list of up to 11 numbers that
alternately represent the lengths of the
dashes and gaps on the cross hair lines.
Each number must be between 1 and 255. If
solid lines.
-hide boolean
Indicates whether cross hairs are drawn. If
boolean is true, cross hairs are not drawn.
The default is yes.
-linewidth pixels
Set the width of the cross hair lines. The
default is 1.
-position pos
Specifies the screen position where the
cross hairs intersect. Pos must be in the
form "@x,y", where x and y are the window
coordinates of the intersection.
Cross hairs configuration options may be also be
set by the option command. The resource name and
class are crosshairs and Crosshairs respectively.
option add *Graph.Crosshairs.LineWidth 2
option add *Graph.Crosshairs.Color red
pathName crosshairs off
Turns off the cross hairs.
pathName crosshairs on
Turns on the display of the cross hairs.
pathName crosshairs toggle
Toggles the current state of the cross hairs,
alternately mapping and unmapping the cross hairs.
ELEMENT COMPONENTS
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.
When new data elements are created, they are automatically
added to a list of displayed elements. The display list
controls what elements are drawn and in what order.
The following operations are available for elements.
pathName element activate elemName ?index?...
Specifies the data points of element elemName to be
drawn using active foreground and background col
ors. ElemName is the name of the element and index
point. If no indices are present then all data
points become active.
pathName element cget elemName option
Returns the current value of the element configura
tion option given by option. Option may be any of
the options described below for the element config
ure operation.
pathName element closest x y varName ?option value?...
?elem Name?...
Finds the data point closest to the window coordi
nates x and y in the element elemName. ElemName is
the name of an element, that must not be hidden.
If no elements are specified, then all visible ele
ments are searched. It returns via the array vari
able varName the name of the closest element, the
index of its closest point, and the graph coordi
nates of the point. Returns 0, if no data point
within the threshold distance can be found, other
wise 1 is returned. The following option-value
pairs are available.
-halo pixels
Specifies a threshold distance where
selected data points are ignored. Pixels is
a valid screen distance, such as 2 or 1.2i.
If this option isn't specified, then it
defaults to the value of the graph's -halo
option.
-interpolate boolean
Indicates that both the data points and
interpolated points along the line segment
formed should be considered. If boolean is
true, the closest line segment will be
selected instead of the closest point. If
this option isn't specified, boolean
defaults to 0.
pathName element configure elemName ?elemName...
?option value?...
Queries or modifies the configuration options for
elements. Several elements can be modified at the
same time. If option isn't specified, a list
describing all the current options for elemName is
returned. If option is specified, but not value,
then a list describing the option option is
returned. If one or more option and value pairs
are specified, then for each pair, the element
option option is set to value. The following
options are valid for elements.
Specifies pen to use to draw active element.
If penName is "", no active elements will be
drawn. The default is activeLine.
-color color
Sets the color of the traces connecting the
data points.
-dashes dashList
Sets the dash style of element line. Dash
List 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 dash
List is "", the lines will be solid.
-data coordList
Specifies the X-Y coordinates of the data.
CoordList is a list of numeric expressions
representing the X-Y coordinate pairs of
each data point.
-fill color
Sets the interior color of symbols. If
color is "", then the interior of the symbol
is transparent. If color is defcolor, then
the color will be the same as the -color
option. The default is defcolor.
-hide boolean
Indicates whether the element is displayed.
The default is no.
-label text
Sets the element's label in the legend. If
text is "", the element will have no entry
in the legend. The default label is the
element's name.
-linewidth pixels
Sets the width of the connecting lines
between data points. If pixels is 0, no
connecting lines will be drawn between sym
bols. The default is 0.
-mapx xAxis
Selects the X-axis to map the element's
X-coordinates onto. XAxis must be the name
of an axis. The default is x.
-mapy yAxis
Selects the Y-axis to map the element's
Y-coordinates onto. YAxis must be the name
-offdash color
Sets the color of the stripes when traces
are dashed (see the -dashes option). If
color is "", then the "off" pixels will rep
resent gaps instead of stripes. If color is
defcolor, then the color will be the same as
the -color option. The default is defcolor.
-outline color
Sets the color or the outline around each
symbol. If color is "", then no outline is
drawn. If color is defcolor, then the color
will be the same as the -color option. The
default is defcolor.
-outlinewidth pixels
Sets the width of the outline bordering each
symbol. If pixels is 0, no outline will be
drawn. The default is 1.
-pixels pixels
Sets the size of symbols. If pixels is 0,
no symbols will be drawn. The default is
0.125i.
-scalesymbols boolean
If boolean is true, the size of the symbols
drawn for elemName 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 -pix
els 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 boolean is false, the element's
symbols are drawn at the designated size,
regardless of axis scales. The default is
0.
-smooth smooth
Specifies how connecting line segments are
drawn between data points. Smooth can be
either linear, step, natural, or quadratic.
If smooth is linear, a single line segment
is drawn, connecting both data points. When
smooth is step, 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-coor
dinate. Both natural and quadratic generate
natural, the segments are generated using a
cubic spline. If quadratic, a quadratic
spline is used. The default is linear.
-styles styleList
Specifies what pen to use based on the range
of weights given. StyleList is a list of
style specifications. Each style specifica
tion, in turn, is a list consisting of a pen
name, and optionally a minimum and maximum
range. Data points whose weight (see the
-weight option) falls in this range, are
drawn with this pen. If no range is speci
fied it defaults to the index of the pen in
the list. Note that this affects only sym
bol attributes. Line attributes, such as
line width, dashes, etc. are ignored.
-symbol symbol
Specifies the symbol for data points. Sym
bol can be either square, circle, diamond,
plus, cross, splus, scross, triangle, ""
(where no symbol is drawn), or a bitmap.
Bitmaps are specified as "source ?mask?",
where source is the name of the bitmap, and
mask is the bitmap's optional mask. The
default is circle.
-trace direction
Indicates whether connecting lines between
data points (whose X-coordinate values are
either increasing or decreasing) are drawn.
Direction must be increasing, decreasing, or
both. For example, if direction is increas
ing, connecting lines will be drawn only
between those data points where X-coordinate
values are monotonically increasing. If
direction is both, connecting lines will be
draw between all data points. The default
is both.
-weights wVec
Specifies the weights of the individual data
points. This, with the list pen styles (see
the -styles option), controls how data
points are drawn. WVec is the name of a BLT
vector or a list of numeric expressions rep
resenting the weights for each data point.
-xdata xVec
Specifies the X-coordinates of the data.
XVec is the name of a BLT vector or a list
of numeric expressions.
Specifies the Y-coordinates of the data.
YVec is the name of a BLT vector or a list
of numeric expressions.
Element configuration options may also be set by
the option command. The resource class is Element.
The resource name is the name of the element.
option add *Graph.Element.symbol line
option add *Graph.e1.symbol line
pathName element create elemName ?option value?...
Creates a new element elemName. It's an error is
an element elemName already exists. If additional
arguments are present, they specify options valid
for the element configure operation.
pathName element deactivate elemName ?elemName?...
Deactivates all the elements matching pattern.
Elements whose names match any of the patterns
given are redrawn using their normal colors.
pathName element delete ?elemName?...
Deletes all the named elements. The graph is auto
matically redrawn.
pathName element exists elemName
Returns 1 if an element elemName currently exists
and 0 otherwise.
pathName element names ?pattern?...
Returns the elements matching one or more pattern.
If no pattern is given, the names of all elements
is returned.
pathName element show ?nameList?
Queries or modifies the element display list. The
element display list designates the elements drawn
and in what order. NameList is a list of elements
to be displayed in the order they are named. If
there is no nameList argument, the current display
list is returned.
pathName element type elemName
Returns the type of elemName. If the element is a
bar element, the commands returns the string "bar",
otherwise it returns "line".
GRID COMPONENT
Grid lines extend from the major and minor ticks of each
axis horizontally or vertically across the plotting area.
pathName grid cget option
Returns the current value of the grid line configu
ration option given by option. Option may be any
option described below for the grid configure oper
ation.
pathName grid configure ?option value?...
Queries or modifies the configuration options for
grid lines. If option isn't specified, a list
describing all the current grid options for path
Name is returned. If option is specified, but not
value, then a list describing option is returned.
If one or more option and value pairs are speci
fied, then for each pair, the grid line option
option is set to value. The following options are
valid for grid lines.
-color color
Sets the color of the grid lines. The
default is black.
-dashes dashList
Sets the dash style of the grid lines. Dash
List 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 dash
List is "", the grid will be solid lines.
-hide boolean
Indicates whether the grid should be drawn.
If boolean is true, grid lines are not
shown. The default is yes.
-linewidth pixels
Sets the width of grid lines. The default
width is 1.
-mapx xAxis
Specifies the X-axis to display grid lines.
XAxis must be the name of an axis. The
default is x.
-mapy yAxis
Specifies the Y-axis to display grid lines.
YAxis must be the name of an axis. The
default is y.
-minor boolean
Indicates whether the grid lines should be
drawn for minor ticks. If boolean is true,
the lines will appear at minor tick
SPEED TIPS
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.
· Try to minimize the number of data points. The more
data points the looked at, the more work the graph must
do.
· If your data is generated as floating point values, the
time required to convert the data values to and from
ASCII strings can be significant, especially when there
any many data points. You can avoid the redundant
string-to-decimal conversions using the C API to BLT
vectors.
· Data elements without symbols are drawn faster than with
symbols. Set the data element's -symbol option to none.
If you need to draw symbols, try using the simple sym
bols such as splus and scross.
· Don't stipple or dash the element. Solid lines are much
faster.
· If you update data elements frequently, try turning off
the widget's -bufferelements 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.
LIMITATIONS
Auto-scale routines do not use requested min/max limits as
boundaries when the axis is logarithmically scaled.
The PostScript output generated for polygons with more
than 1500 points may exceed the limits of some printers
(See PostScript Language Reference Manual, page 568). The
work-around is to break the polygon into separate pieces.
FUTURE INCOMPATIBILITY
The -mapped options are obsoleted and will be removed.
You can achieve the same results using the -hide option
instead.
# Works for now.
# Instead use this.
.g legend configure -hide yes
KEYWORDS
graph, widget
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