NAME¶
barchart - Bar chart for plotting X-Y coordinate data.
SYNOPSIS¶
barchart pathName ?
option value?...
DESCRIPTION¶
The
barchart command creates a bar chart for plotting two-dimensional
data (X-Y coordinates). A bar chart is a graphic means of comparing numbers by
displaying bars of lengths proportional to the y-coordinates of the points
they represented. The bar chart has many configurable components: coordinate
axes, elements, legend, grid lines, cross hairs, etc. They allow you to
customize the look and feel of the graph.
INTRODUCTION¶
The
barchart command creates a new window for plotting two-dimensional
data (X-Y coordinates), using bars of various lengths to represent the data
points. The bars are drawn in a rectangular area displayed in the center of
the new window. This is the
plotting area. The coordinate axes are
drawn in the margins surrounding the plotting area. By default, the legend is
drawn in the right margin. The title is displayed in top margin.
A
barchart widget has several configurable components: coordinate axes,
data elements, legend, grid, cross hairs, pens, postscript, and annotation
markers. Each component can be queried or modified.
- axis
-
Up to four coordinate axes (two X-coordinate and two Y-coordinate axes) can
be displayed, but you can create and use any number of axes. Axes control
what region of data is displayed and how the data is scaled. Each axis
consists of the axis line, title, major and minor ticks, and tick labels.
Tick labels display the value at each major tick.
- crosshairs
- Cross hairs are used to position the mouse pointer relative
to the X and Y coordinate axes. Two perpendicular lines, intersecting at
the current location of the mouse, extend across the plotting area to the
coordinate axes.
- element
- An element represents a set of data to be plotted. It
contains an x and y vector of values representing the data points. Each
data point is displayed as a bar where the length of the bar is
proportional to the ordinate (Y-coordinate) of the data point. The
appearance of the bar, such as its color, stipple, or relief is
configurable.
A special case exists when two or more data points have the same abscissa
(X-coordinate). By default, the bars are overlayed, one on top of the
other. The bars are drawn in the order of the element display list. But
you can also configure the bars to be displayed in two other ways. They
may be displayed as a stack, where each bar (with the same abscissa) is
stacked on the previous. Or they can be drawn side-by-side as thin bars.
The width of each bar is a function of the number of data points with the
same abscissa.
- grid
- Extends the major and minor ticks of the X-axis and/or
Y-axis across the plotting area.
- legend
- The legend displays the name and symbol of each data
element. The legend can be drawn in any margin or in the plotting
area.
- marker
- Markers are used annotate or highlight areas of the graph.
For example, you could use a text marker to label a particular data point.
Markers come in various forms: text strings, bitmaps, connected line
segments, images, polygons, or embedded widgets.
- pen
- Pens define attributes for elements. Data elements use pens
to specify how they should be drawn. A data element may use many pens at
once. Here the particular pen used for a data point is determined from
each element's weight vector (see the element's -weight and
-style options).
- postscript
- The widget can generate encapsulated PostScript output.
This component has several options to configure how the PostScript is
generated.
SYNTAX¶
barchart pathName ?option value?...
The
barchart command creates a new window
pathName and makes it
into a
barchart widget. At the time this command is invoked, there must
not exist a window named
pathName, but
pathName's parent must
exist. Additional options may be specified on the command line or in the
option database to configure aspects of the graph such as its colors and font.
See the
configure operation below for the exact details about what
option and
value pairs are valid.
If successful,
barchart returns the path name of the widget. It also
creates a new Tcl command by the same name. You can use this command to invoke
various operations that query or modify the graph. The general form is:
pathName operation ?arg?...
Both
operation and its arguments determine the exact behavior of the
command. The operations available for the graph are described in the
BARCHART OPERATIONS section.
The command can also be used to access components of the graph.
pathName component operation ?arg?...
The operation, now located after the name of the component, is the function to
be performed on that component. Each component has its own set of operations
that manipulate that component. They will be described below in their own
sections.
EXAMPLE¶
The
barchart command creates a new bar chart.
# Create a new bar chart. Plotting area is black.
barchart .b -plotbackground black
A new Tcl command .b is created. This command can be used to query and modify
the bar chart. For example, to change the title of the graph to "My
Plot", you use the new command and the
configure operation.
# Change the title.
.b configure -title "My Plot"
To add data elements, you use the command and the
element component.
# Create a new element named "e1"
.b element create e1 \
-xdata { 1 2 3 4 5 6 7 8 9 10 } \
-ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14
155.85 166.60 175.38 }
The element's X-Y coordinates are specified using lists of numbers. Alternately,
BLT vectors could be used to hold the X-Y coordinates.
# Create two vectors and add them to the barchart.
vector xVector yVector
xVector set { 1 2 3 4 5 6 7 8 9 10 }
yVector set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85
166.60 175.38 }
n.b element create e1 -xdata xVector -ydata yVector
The advantage of using vectors is that when you modify one, the graph is
automatically redrawn to reflect the new values.
# Change the y coordinate of the first point.
set yVector(0) 25.18
An element named e1 is now created in .b. It is automatically added to the
display list of elements. You can use this list to control in what order
elements are displayed. To query or reset the element display list, you use
the element's
show operation.
# Get the current display list
set elemList [.b element show]
# Remove the first element so it won't be displayed.
.b element show [lrange $elemList 0 end]
The element will be displayed by as many bars as there are data points (in this
case there are ten). The bars will be drawn centered at the x-coordinate of
the data point. All the bars will have the same attributes (colors, stipple,
etc). The width of each bar is by default one unit. You can change this with
using the
-barwidth option.
# Change the scale of the x-coordinate data
xVector set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
# Make sure we change the bar width too.
.b configure -barwidth 0.2
The height of each bar is proportional to the ordinate (Y-coordinate) of the
data point.
If two or more data points have the same abscissa (X-coordinate value), the bars
representing those data points may be drawn in various ways. The default is to
overlay the bars, one on top of the other. The ordering is determined from the
of element display list. If the stacked mode is selected (using the
-barmode configuration option), the bars are stacked, each bar above
the previous.
# Display the elements as stacked.
.b configure -barmode stacked
If the aligned mode is selected, the bars having the same x-coordinates are
displayed side by side. The width of each bar is a fraction of its normal
width, based upon the number of bars with the same x-coordinate.
# Display the elements side-by-side.
.b configure -barmode aligned
By default, the element's label in the legend will be also e1. You can change
the label, or specify no legend entry, again using the element's
configure operation.
# Don't display "e1" in the legend.
.b element configure e1 -label ""
You can configure more than just the element's label. An element has many
attributes such as stipple, foreground and background colors, relief, etc.
.b element configure e1 -fg red -bg pink \
-stipple gray50
Four coordinate axes are automatically created: x, x2, y, and y2. And by
default, elements are mapped onto the axes x and y. This can be changed with
the
-mapx and
-mapy options.
# Map "e1" on the alternate y axis "y2".
.b element configure e1 -mapy y2
Axes can be configured in many ways too. For example, you change the scale of
the Y-axis from linear to log using the
axis component.
# Y-axis is log scale.
.b axis configure y -logscale yes
One important way axes are used is to zoom in on a particular data region.
Zooming is done by simply specifying new axis limits using the
-min and
-max configuration options.
.b axis configure x -min 1.0 -max 1.5
.b axis configure y -min 12.0 -max 55.15
To zoom interactively, you link the
axis configure operations with some
user interaction (such as pressing the mouse button), using the
bind
command. To convert between screen and graph coordinates, use the
invtransform operation.
# Click the button to set a new minimum
bind .b <ButtonPress-1> {
%W axis configure x -min [%W axis invtransform x %x]
%W axis configure x -min [%W axis invtransform x %y]
}
By default, the limits of the axis are determined from data values. To reset
back to the default limits, set the
-min and
-max options to the
empty value.
# Reset the axes to autoscale again.
.b axis configure x -min {} -max {}
.b axis configure y -min {} -max {}
By default, the legend is drawn in the right margin. You can change this or any
legend configuration options using the
legend component.
# Configure the legend font, color, and relief
.b legend configure -position left -relief raised \
-font fixed -fg blue
To prevent the legend from being displayed, turn on the
-hide option.
# Don't display the legend.
.b legend configure -hide yes
The
barchart has simple drawing procedures called markers. They can be
used to highlight or annotate data in the graph. The types of markers
available are bitmaps, polygons, lines, or windows. Markers can be used, for
example, to mark or brush points. For example there may be a line marker which
indicates some low-water value. Markers are created using the
marker
operation.
# Create a line represent the low water mark at 10.0
.b marker create line -name "low_water" \
-coords { -Inf 10.0 Inf 10.0 } \
-dashes { 2 4 2 } -fg red -bg blue
This creates a line marker named low_water. It will display a horizontal line
stretching across the plotting area at the y-coordinate 10.0. The coordinates
"-Inf" and "Inf" indicate the relative minimum and maximum
of the axis (in this case the x-axis). By default, markers are drawn last, on
top of the bars. You can change this with the
-under option.
# Draw the marker before elements are drawn.
.b marker configure low_water -under yes
You can add cross hairs or grid lines using the
crosshairs and
grid components.
# Display both cross hairs and grid lines.
.b crosshairs configure -hide no -color red
.b grid configure -hide no -dashes { 2 2 }
Finally, to get hardcopy of the graph, use the
postscript component.
# Print the bar chart into file "file.ps"
.b postscript output file.ps -maxpect yes -decorations no
This generates a file file.ps containing the encapsulated PostScript of the
graph. The option
-maxpect says to scale the plot to the size of the
page. Turning off the
-decorations option denotes that no borders or
color backgrounds should be drawn (i.e. the background of the margins, legend,
and plotting area will be white).
SYNTAX¶
barchart pathName ?option value?...
The
barchart command creates a new window
pathName and makes it
into a barchart widget. At the time this command is invoked, there must not
exist a window named
pathName, but
pathName's parent must exist.
Additional options may may be specified on the command line or in the option
database to configure aspects of the bar chart such as its colors and font.
See the
configure operation below for the exact details as to what
option and
value pairs are valid.
If successful,
barchart returns
pathName. It also creates a new
Tcl command
pathName. This command may be used to invoke various
operations to query or modify the bar chart. It has the general form:
pathName operation ?arg?...
Both
operation and its arguments determine the exact behavior of the
command. The operations available for the bar chart are described in the
following section.
BARCHART OPERATIONS¶
- pathName bar elemName ?option
value?...
- Creates a new barchart element elemName. It's an
error if an element elemName already exists. See the manual for
barchart for details about what option and value
pairs are valid.
- pathName cget option
- Returns the current value of the configuration option given
by option. Option may be any option described below for the
configure operation.
- pathName configure ?option
value?...
- Queries or modifies the configuration options of the graph.
If option isn't specified, a list describing the current options
for pathName is returned. If option is specified, but not
value, then a list describing option is returned. If one or
more option and value pairs are specified, then for each
pair, the option option is set to value. The following
options are valid.
- -background color
- Sets the background color. This includes the margins and
legend, but not the plotting area.
- -barmode mode
- Indicates how related bar elements will be drawn. Related
elements have data points with the same abscissas (X-coordinates).
Mode indicates how those segments should be drawn. Mode can
be infront, aligned, overlap, or stacked. The default mode is
infront.
- infront
- Each successive segment is drawn in front of the
previous.
- stacked
- Each successive segment is stacked vertically on top of the
previous.
- aligned
- Segments is displayed aligned from right-to-left.
- overlap
- Like aligned but segments slightly overlap each other.
- -barwidth value
- Specifies the width of the bars. This value can be
overridden by the individual elements using their -barwidth
configuration option. Value is the width in terms of graph
coordinates. The default width is 1.0.
- -borderwidth pixels
- Sets the width of the 3-D border around the outside edge of
the widget. The -relief option determines if the 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
section. The default is 1.
- -cursor cursor
- Specifies the widget's cursor. The default cursor is
crosshair.
- -font fontName
- Specifies the font of the graph title. The default is
*-Helvetica-Bold-R-Normal-*-18-180-*.
- -halo pixels
- Specifies a maximum distance to consider when searching for
the closest data point (see the element's closest operation below).
Data points further than pixels away are ignored. The default is
0.5i.
- -height pixels
- Specifies the requested height of widget. The default is
4i.
- -invertxy boolean
- Indicates whether the placement X-axis and Y-axis should be
inverted. If boolean is true, the X and Y axes are swapped. The
default is 0.
- -justify justify
- Specifies how the title should be justified. This matters
only when the title contains more than one line of text. Justify
must be left, right, or center. The default is center.
- -leftmargin pixels
- Sets the size of the margin from the left edge of the
window to the Y-coordinate axis. If pixels is 0, the size is
calculated automatically. The default is 0.
- -plotbackground color
- Specifies the background color of the plotting area. The
default is white.
- -plotborderwidth pixels
- Sets the width of the 3-D border around the plotting area.
The -plotrelief option determines if a border is drawn. The default
is 2.
- -plotpadx pad
- Sets the amount of padding to be added to the left and
right sides of the plotting area. Pad can be a list of one or two
screen distances. If pad has two elements, the left side of the
plotting area entry is padded by the first distance and the right side by
the second. If pad is just one distance, both the left and right
sides are padded evenly. The default is 8.
- -plotpady pad
- Sets the amount of padding to be added to the top and
bottom of the plotting area. Pad can be a list of one or two screen
distances. If pad has two elements, the top of the plotting area is
padded by the first distance and the bottom by the second. If pad
is just one distance, both the top and bottom are padded evenly. The
default is 8.
- -plotrelief relief
- Specifies the 3-D effect for the plotting area.
Relief specifies how the interior of the plotting area should
appear relative to rest of the graph; for example, raised means the plot
should appear to protrude from the graph, relative to the surface of the
graph. The default is sunken.
- -relief relief
- Specifies the 3-D effect for the barchart widget.
Relief specifies how the graph should appear relative to widget it
is packed into; for example, raised means the graph should appear to
protrude. The default is flat.
- -rightmargin pixels
- Sets the size of margin from the plotting area to the right
edge of the window. By default, the legend is drawn in this margin. If
pixels is than 1, the margin size is selected automatically.
- -takefocus focus
- Provides information used when moving the focus from 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 background color is drawn (see the
-background option). Image must be an image created using
the Tk image command. The default is "".
- -title text
- Sets the title to text. If text is
"", no title will be displayed.
- -topmargin pixels
- Specifies the size of the margin above the x2 axis. If
pixels is 0, the margin size is calculated automatically.
- -width pixels
- Specifies the requested width of the widget. The default is
5i.
- pathName crosshairs operation
?arg?
- See the CROSSHAIRS COMPONENT
section.
- pathName element operation
?arg?...
- See the ELEMENT COMPONENTS
section.
- pathName extents item
- Returns the size of a particular item in the graph.
Item must be either leftmargin, rightmargin, topmargin,
bottommargin, plotwidth, or plotheight.
- pathName grid operation
?arg?...
- See the GRID COMPONENT section.
- pathName invtransform winX winY
- Performs an inverse coordinate transformation, mapping
window coordinates back to graph coordinates, using the standard X-axis
and Y-axis. Returns a list of containing the X-Y graph 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 metafile ?fileName?
- This operation is for Window platforms only. Creates
a Windows enhanced metafile of the barchart. If present, fileName
is the file name of the new metafile. Otherwise, the metafile is
automatically added to the clipboard.
- pathName postscript operation
?arg?...
- See the POSTSCRIPT COMPONENT
section.
- pathName snap photoName
- Takes a snapshot of the graph and stores the contents in
the photo image photoName. PhotoName is the name of a Tk
photo image that must already exist.
- pathName transform x y
- Performs a coordinate transformation, mapping graph
coordinates to window coordinates, using the standard X-axis and Y-axis.
Returns a list containing the X-Y screen coordinates.
- pathName xaxis operation
?arg?...
- pathName x2axis operation
?arg?...
- pathName yaxis operation
?arg?...
- pathName y2axis operation
?arg?...
- See the AXIS COMPONENTS section.
BARCHART COMPONENTS¶
A graph is composed of several components: coordinate axes, data 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.
AXIS COMPONENTS¶
Four coordinate axes are automatically created: two X-coordinate axes (x and x2)
and two Y-coordinate axes (y, and y2). By default, the axis x is located in
the bottom margin, y in the left margin, x2 in the top margin, and y2 in the
right margin.
An axis consists of the axis line, title, major and minor ticks, and tick
labels. Major ticks are drawn at uniform intervals along the axis. Each tick
is labeled with its coordinate value. Minor ticks are drawn at uniform
intervals within major ticks.
The range of the axis controls what region of data is plotted. Data points
outside the minimum and maximum limits of the axis are not 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 "temperature"
.b axis create temperature
You map data elements to an axis using the element's -mapy and -mapx
configuration options. They specify the coordinate axes an element is mapped
onto.
# Now map the temperature data to this axis.
.b element create "temp" -xdata $x -ydata $tempData \
-mapy temperature
While you can have many axes, only four axes can be displayed simultaneously.
They are drawn in each of the margins surrounding 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 following components:
xaxis,
yaxis,
x2axis, and
y2axis. The
use
operation designates the axis to be drawn in the corresponding margin:
xaxis in the bottom,
yaxis in the left,
x2axis in the
top, and
y2axis in the right.
# Display the axis temperature in the left margin.
.b yaxis use temperature
You can configure axes in many ways. The axis scale can be linear or
logarithmic. The values along the axis can either monotonically increase or
decrease. If you need custom tick labels, you can specify a Tcl procedure to
format the label any way you wish. You can control how ticks are drawn, by
changing the major tick interval or the number of minor ticks. You can define
non-uniform tick intervals, such as for time-series plots.
- pathName axis cget axisName
option
- Returns the current value of the option given by
option for axisName. Option may be any option
described below for the axis configure operation.
- pathName axis configure axisName
? axisName?... ?option value?...
- Queries or modifies the configuration options of
axisName. 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.
- -autorange range
- Sets the range of values for the axis to range. The
axis limits are automatically reset to display the most recent data points
in this range. If range is 0.0, the range is determined from the
limits of the data. If -min or -max are specified, they
override this option. The default is 0.0.
- -color color
- Sets the color of the axis and tick labels. The default is
black.
- -command prefix
- Specifies a Tcl command to be invoked when formatting the
axis tick labels. Prefix is a string containing the name of a Tcl
proc and any extra arguments for the procedure. This command is invoked
for each major tick on the axis. Two additional arguments are passed to
the procedure: the pathname of the widget and the current the numeric
value of the tick. The procedure returns the formatted tick label. If
"" is returned, no label will appear next to the tick. You can
get the standard tick labels again by setting prefix to
"". The default is "".
Please note that this procedure is invoked while the bar chart is redrawn.
You may query the widget's configuration options. But do not reset
options, 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 justified. This
matters only when the axis title contains more than one line of text.
Justify must be left, right, or center. The default is center.
- -limits formatStr
- Specifies a printf-like description to format the minimum
and maximum limits of the axis. The limits are displayed at the top/bottom
or left/right sides of the plotting area. FormatStr is a list of
one or two format 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 calculated. If boolean is true, the axis range is
"loose". The default is 0.
- -majorticks majorList
- Specifies where to display major axis ticks. You can use
this option to display ticks at non-uniform intervals. MajorList is
a list of axis coordinates designating the location of major ticks. No
minor ticks are drawn. If majorList is "", major ticks
will be automatically computed. The default is "".
- -max value
- Sets the maximum limit of axisName. Any data point
greater than value is not displayed. If value is
"", the maximum limit is calculated using the largest data
value. The default is "".
- -min value
- Sets the minimum limit of axisName. Any data point
less than value is not displayed. If value is "",
the minimum limit is calculated using the smallest data value. The default
is "".
- -minorticks minorList
- Specifies where to display minor axis ticks. You can use
this option to display minor ticks at non-uniform 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.
- -shiftby value
- Specifies how much to automatically shift the range of the
axis. When the new data exceeds the current axis maximum, the maximum is
increased in increments of value. You can use this option to
prevent the axis limits from being recomputed at each new time point. If
value is 0.0, then no automatic shifting is down. The default is
0.0.
- -showticks boolean
- Indicates whether axis ticks should be drawn. If
boolean is true, ticks are drawn. If false, only the axis line is
drawn. The default is 1.
- -stepsize value
- Specifies the interval between major axis ticks. If
value isn't a valid interval (must be less than the axis range),
the request is ignored and the step size is automatically calculated.
- -subdivisions number
- Indicates how many minor axis ticks are to be drawn. For
example, if number is two, only one minor tick is drawn. If
number is one, no minor ticks are displayed. The default is 2.
- -tickfont fontName
- Specifies the font for axis tick labels. The default is
*-Courier-Bold-R-Normal-*-100-*.
- -ticklength pixels
- Sets the length of major and minor ticks (minor ticks are
half the length of major ticks). If pixels is less than zero, the
axis will be inverted with ticks drawn pointing towards the plot. The
default is 0.1i.
- -title text
- Sets the title of the axis. If text is "",
no axis title will be displayed.
- -titlecolor color
- Sets the color of the axis title. The default is
black.
- -titlefont fontName
- Specifies the font for axis title. The default is
*-Helvetica-Bold-R-Normal-*-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 *Barchart.Axis.Color blue
option add *Barchart.x.LogScale true
option add *Barchart.x2.LogScale false
- pathName axis create axisName
?option value?...
- Creates a new axis by the name axisName. No axis by
the same name can already exist. Option and value are
described in above in the axis configure operation.
- pathName axis delete
?axisName?...
- Deletes the named axes. An axis is not really deleted until
it is not longer in use, so it's safe to delete axes mapped to
elements.
- pathName axis invtransform axisName
value
- Performs the inverse transformation, changing the screen
coordinate value to a graph coordinate, mapping the value mapped to
axisName. Returns the graph coordinate.
- pathName axis limits axisName
- Returns a list of the minimum and maximum limits for
axisName. The order of the list is min max.
- pathName axis names ?pattern?...
- Returns a list of axes matching zero or more patterns. If
no pattern argument is give, the names of all axes are
returned.
- pathName axis transform axisName
value
- Transforms the coordinate value to a screen
coordinate by 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 components:
xaxis,
x2axis,
yaxis, and
y2axis.
.g create axis temp
.g create axis time
...
.g xaxis use temp
.g yaxis use time
Only the axes specified for use are displayed on the screen.
The
xaxis,
x2axis,
yaxis, and
y2axis components
operate on an axis location rather than a specific axis like the more general
axis 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 mirror exactly the
operations of the
axis component. The
axis argument must be
xaxis,
x2axis,
yaxis, or
y2axis.
- pathName axis cget option
- pathName axis configure ?option
value?...
- pathName axis invtransform
value
- pathName axis limits
- pathName axis transform
value
- pathName axis use
?axisName?
- Designates the axis axisName is to be displayed at
this 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 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 widget.
The following operations are available for cross hairs:
- pathName crosshairs cget option
- Returns the current value of the cross hairs configuration
option given by option. Option may be any option described
below for the cross hairs configure operation.
- pathName crosshairs configure ?option
value?...
- Queries or modifies the configuration options of the cross
hairs. If option isn't specified, a list describing all the current
options for the cross hairs is returned. If option is specified,
but not value, then a list describing option is returned. If
one or more option and value pairs are specified, then for
each pair, the cross hairs option option is set to value.
The following options are available for cross hairs.
- -color color
- Sets the color of the cross hairs. The default is
black.
- -dashes dashList
- Sets the dash style of the cross hairs. DashList is
a list of up to 11 numbers that alternately represent the lengths of the
dashes and gaps on the cross hair lines. Each number must be between 1 and
255. If dashList is "", the cross hairs will be solid
lines.
- -hide boolean
- Indicates whether cross hairs are drawn. If boolean
is true, cross hairs are not drawn. The default is yes.
- -linewidth pixels
- Set the width of the cross hair lines. The default is
1.
- -position pos
- Specifies the screen position where the cross hairs
intersect. Pos must be in the form "@x,y", where
x and y are the window coordinates of the intersection.
Cross hairs configuration options may be also be set by the
option
command. The resource name and class are crosshairs and Crosshairs
respectively.
option add *Barchart.Crosshairs.LineWidth 2
option add *Barchart.Crosshairs.Color red
- pathName crosshairs off
- Turns off the cross hairs.
- pathName crosshairs on
- Turns on the display of the cross hairs.
- pathName crosshairs toggle
- Toggles the current state of the cross hairs, alternately
mapping and unmapping the cross hairs.
ELEMENTS¶
A data element represents a set of data. It contains x and y vectors which are
the coordinates of the data points. Elements are displayed as bars where the
length of the bar is proportional to the ordinate of the data point. Elements
also control the appearance of the data, such as the color, stipple, relief,
etc.
When new data elements are created, they are automatically added to a list of
displayed elements. The display list controls what elements are drawn and in
what order.
The following operations are available for elements.
- pathName element activate elemName
?index?...
- Specifies the data points of element elemName to be
drawn using active foreground and background colors. ElemName is
the name of the element and index is a number representing the
index of the data point. If no indices are present then all data points
become active.
- pathName element bind tagName
?sequence? ? command?
- Associates command with tagName such that
whenever the event sequence given by sequence occurs for an element
with this tag, command will be invoked. The syntax is similar to
the bind command except that it operates on graph elements, rather
than widgets. See the bind manual entry for complete details on
sequence and the substitutions performed on command before
invoking it.
If all arguments are specified then a new binding is created, replacing any
existing binding for the same sequence and tagName. If the
first character of command is + then command augments an
existing binding rather than replacing it. If no command argument
is provided then the command currently associated with tagName and
sequence (it's an error occurs if there's no such binding) is
returned. If both command and sequence are missing then a
list of all the event sequences for which bindings have been defined for
tagName.
- pathName element cget elemName
option
- Returns the current value of the element configuration
option given by option. Option may be any of the options
described below for the element configure operation.
- pathName element closest x y
?option value?... ? elemName?...
- Finds the data point representing the bar closest to the
window coordinates x and y in the element elemName.
ElemName is the name of an element, which must be displayed. If no
elements are specified, then all displayed elements are searched. It
returns a list containing the name of the closest element, the index of
its closest point, and the graph coordinates of the point. If no data
point within the threshold distance can be found, "" is
returned. The following option-value pairs are
available.
- -halo pixels
- Specifies a threshold distance where selected data points
are ignored. Pixels is a valid screen distance, such as 2 or 1.2i.
If this option isn't specified, then it defaults to the value of the
barchart's -halo option.
- pathName element configure elemName
?elemName... ?option value?...
- Queries or modifies the configuration options for elements.
Several elements can be modified at the same time. If option isn't
specified, a list describing all the current options for elemName
is returned. If option is specified, but not value, then a
list describing the option option is returned. If one or more
option and value pairs are specified, then for each pair,
the element option option is set to value. The following
options are valid for elements.
- -activepen penName
- Specifies pen to use to draw active element. If
penName is "", no active elements will be drawn. The
default is activeLine.
- -bindtags tagList
- Specifies the binding tags for the element. TagList
is a list of binding tag names. The tags and their order will determine
how events for elements. Each tag in the list matching the current event
sequence will have its Tcl command executed. Implicitly the name of the
element is always the first tag in the list. The default value is
all.
- -background color
- Sets the the color of the border around each bar. The
default is white.
- -barwidth value
- Specifies the width the bars drawn for the element.
Value is the width in X-coordinates. If this option isn't
specified, the width of each bar is the value of the widget's
-barwidth option.
- -baseline value
- Specifies the baseline of the bar segments. This affects
how bars are drawn since bars are drawn from their respective y-coordinate
the baseline. By default the baseline is 0.0.
- -borderwidth pixels
- Sets the border width of the 3-D border drawn around the
outside of each bar. The -relief option determines if such a border
is drawn. Pixels must be a valid screen distance like 2 or 0.25i.
The default is 2.
- -data coordList
- Specifies the X-Y coordinates of the data. CoordList
is a list of numeric expressions representing the X-Y coordinate pairs of
each data point.
- -foreground color
- Sets the color of the interior of the bars.
- -hide boolean
- Indicates whether the element is displayed. The default is
no.
- -label text
- Sets the element's label in the legend. If text is
"", the element will have no entry in the legend. The default
label is the element's name.
- -mapx xAxis
- Selects the X-axis to map the element's X-coordinates onto.
XAxis must be the name of an axis. The default is x.
- -mapy yAxis
- Selects the Y-axis to map the element's Y-coordinates onto.
YAxis must be the name of an axis. The default is y.
- -relief string
- Specifies the 3-D effect desired for bars. Relief
indicates how the interior of the bar should appear relative to the
surface of the chart; for example, raised means the bar should appear to
protrude from the surface of the plotting area. The default is
raised.
- -stipple bitmap
- Specifies a stipple pattern with which to draw the bars. If
bitmap is "", then the bar is drawn in a solid
fashion.
- -xdata xVector
- Specifies the x-coordinate vector of the data.
XVector is the name of a BLT vector or a list of numeric
expressions.
- -ydata yVector
- Specifies the y-coordinate vector of the data.
YVector 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 names in the option database are prefixed by elem.
option add *Barchart.Element.background blue
- pathName element create elemName
?option value?...
- Creates a new element elemName. Element names must
be unique, so an element elemName may not already exist. If
additional arguments are present, they specify any of the element options
valid for element configure operation.
- pathName element deactivate
pattern...
- Deactivates all the elements matching pattern for
the graph. Elements whose names match any of the patterns given are
redrawn using their normal colors.
- pathName element delete
?pattern?...
- Deletes all the elements matching pattern for the
graph. Elements whose names match any of the patterns given are deleted.
The graph will be redrawn without the deleted elements.
- pathName element exists elemName
- Returns 1 if an element elemName currently exists
and 0 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. The following operations are available
for grid lines.
- pathName grid cget option
- Returns the current value of the grid line configuration
option given by option. Option may be any option described
below for the grid configure operation.
- pathName grid configure ?option
value?...
- Queries or modifies the configuration options for grid
lines. If option isn't specified, a list describing all the current
grid options for pathName is returned. If option is
specified, but not value, then a list describing option is
returned. If one or more option and value pairs are
specified, then for each pair, the grid line option option is set
to value. The 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. DashList is a
list of up to 11 numbers that alternately represent the lengths of the
dashes and gaps on the grid lines. Each number must be between 1 and 255.
If dashList is "", the grid will be solid lines.
- -hide boolean
- Indicates whether the grid should be drawn. If
boolean is true, grid lines are not shown. The default is yes.
- -linewidth pixels
- Sets the width of grid lines. The default width is 1.
- -mapx xAxis
- Specifies the X-axis to display grid lines. XAxis
must be the name of an axis or "" for no grid lines. The default
is "".
- -mapy yAxis
- Specifies the Y-axis to display grid lines. YAxis
must be the name of an axis or "" for no grid lines. The default
is y.
- -minor boolean
- Indicates whether the grid lines should be drawn for minor
ticks. If boolean is true, the lines will appear at minor tick
intervals. The default is 1.
Grid configuration options may also be set by the
option command. The
resource name and class are grid and Grid respectively.
option add *Barchart.grid.LineWidth 2
option add *Barchart.Grid.Color black
- pathName grid off
- Turns off the display the grid lines.
- pathName grid on
- Turns on the display the grid lines.
- pathName grid toggle
- Toggles the display of the grid.
LEGEND COMPONENT¶
The legend displays a list of the data elements. Each entry consists of the
element's symbol and label. The legend can appear in any margin (the default
location is in the right margin). It can also be positioned anywhere within
the plotting area.
The following operations are valid for the legend.
- pathName legend activate
pattern...
- Selects legend entries to be drawn using the active legend
colors and relief. All entries whose element names match pattern
are selected. To be selected, the element name must match only one
pattern.
- pathName legend bind tagName
?sequence? ? command?
- Associates command with tagName such that
whenever the event sequence given by sequence occurs for a legend
entry with this tag, command will be invoked. Implicitly the
element names in the entry are tags. The syntax is similar to the
bind command except that it operates on legend entries, rather than
widgets. See the bind manual entry for complete details on
sequence and the substitutions performed on command before
invoking it.
If all arguments are specified then a new binding is created, replacing any
existing binding for the same sequence and tagName. If the
first character of command is + then command augments an
existing binding rather than replacing it. If no command argument
is provided then the command currently associated with tagName and
sequence (it's an error occurs if there's no such binding) is
returned. If both command and sequence are missing then a
list of all the event sequences for which bindings have been defined for
tagName.
- pathName legend cget option
- Returns the current value of a legend configuration option.
Option may be any option described below in the legend
configure operation.
- pathName legend configure ?option
value?...
- Queries or modifies the configuration options for the
legend. If option isn't specified, a list describing the current
legend options for pathName is returned. If option is
specified, but not value, then a list describing option is
returned. If one or more option and value pairs are
specified, then for each pair, the legend option option is set to
value. The following options are valid for the legend.
- -activebackground color
- Sets the background color for active legend entries. All
legend entries marked active (see the legend activate operation)
are drawn using this background color.
- -activeborderwidth pixels
- Sets the width of the 3-D border around the outside edge of
the active legend entries. The default is 2.
- -activeforeground color
- Sets the foreground color for active legend entries. All
legend entries marked as active (see the legend activate operation)
are drawn using this foreground color.
- -activerelief relief
- Specifies the 3-D effect desired for active legend entries.
Relief denotes how the interior of the entry should appear relative
to the legend; for example, raised means the entry should appear to
protrude from the legend, relative to the surface of the legend. The
default is flat.
- -anchor anchor
- Tells how to position the legend relative to the
positioning point for the legend. This is dependent on the value of the
-position option. The default is center.
- left or right
- The anchor describes how to position the legend
vertically.
- top or bottom
- The anchor describes how to position the legend
horizontally.
- @x,y
- The anchor specifies how to position the legend relative to
the positioning point. For example, if anchor is center then the
legend is centered on the point; if anchor is n then the legend
will be drawn such that the top center point of the rectangular region
occupied by the legend will be at the positioning point.
- plotarea
- The anchor specifies how to position the legend relative to
the plotting area. For example, if anchor is center then the legend
is centered in the plotting area; if anchor is ne then the legend
will be drawn such that occupies the upper right corner of the plotting
area.
- -background color
- Sets the background color of the legend. If color is
"", the legend background with be transparent.
- -bindtags tagList
- Specifies the binding tags for legend entries.
TagList is a list of binding tag names. The tags and their order
will determine how events for legend entries. Each tag in the list
matching the current event sequence will have its Tcl command executed.
The default value is all.
- -borderwidth pixels
- Sets the width of the 3-D border around the outside edge of
the legend (if such border is being drawn; the relief option
determines this). The default is 2 pixels.
- -font fontName
- FontName specifies a font to use when drawing the
labels of each element into the legend. The default is
*-Helvetica-Bold-R-Normal-*-12-120-*.
- -foreground color
- Sets the foreground color of the text drawn for the
element's label. The default is black.
- -hide boolean
- Indicates whether the legend should be displayed. If
boolean is true, the legend will not be draw. The default is
no.
- -ipadx pad
- Sets the amount of internal padding to be added to the
width of each legend entry. Pad can be a list of one or two screen
distances. If pad has two elements, the left side of the legend
entry is padded by the first distance and the right side by the second. If
pad is just one distance, both the left and right sides are padded
evenly. The default is 2.
- -ipady pad
- Sets an amount of internal padding to be added to the
height of each legend entry. Pad can be a list of one or two screen
distances. If pad has two elements, the top of the entry is padded
by the first distance and the bottom by the second. If pad is just
one distance, both the top and bottom of the entry are padded evenly. The
default is 2.
- -padx pad
- Sets the padding to the left and right exteriors of the
legend. Pad can be a list of one or two screen distances. If
pad has two elements, the left side of the legend is padded by the
first distance and the right side by the second. If pad has just
one distance, both the left and right sides are padded evenly. The default
is 4.
- -pady pad
- Sets the padding above and below the legend. Pad can
be a list of one or two screen distances. If pad has two elements,
the area above the legend is padded by the first distance and the area
below by the second. If pad is just one distance, both the top and
bottom areas are padded evenly. The default is 0.
- -position pos
- Specifies where the legend is drawn. The -anchor
option also affects where the legend is positioned. If pos is left,
left, top, or bottom, the legend is drawn in the specified margin. If
pos is plotarea, then the legend is drawn inside the plotting area
at a particular anchor. If pos is in the form
"@x,y", where x and y are the window
coordinates, the legend is drawn in the plotting area at the specified
coordinates. The default is right.
- -raised boolean
- Indicates whether the legend is above or below the data
elements. This matters only if the legend is in the plotting area. If
boolean is true, the legend will be drawn on top of any elements
that may overlap it. The default is no.
- -relief relief
- Specifies the 3-D effect for the border around the legend.
Relief specifies how the interior of the legend should appear
relative to the bar chart; for example, raised means the legend should
appear to protrude from the bar chart, relative to the surface of the bar
chart. The default is sunken.
Legend configuration options may also be set by the
option command. The
resource name and class are legend and Legend respectively.
option add *Barchart.legend.Foreground blue
option add *Barchart.Legend.Relief raised
- pathName legend deactivate
pattern...
- Selects legend entries to be drawn using the normal legend
colors and relief. All entries whose element names match pattern
are selected. To be selected, the element name must match only one
pattern.
- pathName legend get pos
- Returns the name of the element whose entry is at the
screen position pos in the legend. Pos must be in the form
" @x,y", where x and y are window
coordinates. If the given coordinates do not lie over a legend entry,
"" is returned.
PEN COMPONENTS¶
Pens define attributes for elements. Pens mirror the configuration options of
data elements that pertain to how symbols and lines are drawn. Data elements
use pens to determine how they are drawn. A data element may use several pens
at once. In this case, the pen used for a particular data point is determined
from each element's weight vector (see the element's
-weight and
-style options).
One pen, called activeBar, is automatically created. It's used as the default
active pen for elements. So you can change the active attributes for all
elements by simply reconfiguring this pen.
.g pen configure "activeBar" -fg green -bg green4
You can create and use several pens. To create a pen, invoke the pen component
and its create operation.
You map pens to a data element using either the element's
-pen or
-activepen options.
.g element create "e1" -xdata $x -ydata $tempData \
-pen myPen
An element can use several pens at once. This is done by specifying the name of
the pen in the element's style list (see the
-styles option).
.g element configure "e1" -styles { myPen 2.0 3.0 }
This says that any data point with a weight between 2.0 and 3.0 is to be drawn
using the pen myPen. All other points are drawn with the element's default
attributes.
The following operations are available for pen components.
- pathName pen cget penName
option
- Returns the current value of the option given by
option for penName. Option may be any option
described below for the pen configure operation.
- pathName pen configure penName
? penName... ?option value?...
- Queries or modifies the configuration options of
penName. Several pens can be modified at once. If option
isn't specified, a list describing the current options for penName
is returned. If option is specified, but not value, then a
list describing option is returned. If one or more option
and value pairs are specified, then for each pair, the pen option
option is set to value. The following options are valid for
pens.
- -background color
- Sets the the color of the border around each bar. The
default is white.
- -borderwidth pixels
- Sets the border width of the 3-D border drawn around the
outside of each bar. The -relief option determines if such a border
is drawn. Pixels must be a valid screen distance like 2 or 0.25i.
The default is 2.
- -foreground color
- Sets the color of the interior of the bars.
- -relief string
- Specifies the 3-D effect desired for bars. Relief
indicates how the interior of the bar should appear relative to the
surface of the chart; for example, raised means the bar should appear to
protrude from the bar chart, relative to the surface of the plotting area.
The default is raised.
- -stipple bitmap
- Specifies a stipple pattern with which to draw the bars. If
bitmap is "", then the bar is drawn in a solid
fashion.
- -type elemType
- Specifies the type of element the pen is to be used with.
This option should only be employed when creating the pen. This is for
those that wish to mix different types of elements (bars and lines) on the
same graph. The default type is "bar".
Pen configuration options may be also be set by the
option command. The
resource class is Pen. The resource names are the names of the pens.
option add *Barchart.Pen.Foreground blue
option add *Barchart.activeBar.foreground green
- pathName pen create penName
?option value?...
- Creates a new pen by the name penName. No pen by the
same name can already exist. Option and value are described
in above in the pen configure operation.
- pathName pen delete
?penName?...
- Deletes the named pens. A pen is not really deleted until
it is not longer in use, so it's safe to delete pens mapped to
elements.
- pathName pen names ?pattern?...
- Returns a list of pens matching zero or more patterns. If
no pattern argument is give, the names of all pens are
returned.
POSTSCRIPT COMPONENT¶
The barchart can generate encapsulated PostScript output. There are several
configuration options you can specify to control how the plot will be
generated. You can change the page dimensions and borders. The plot itself can
be scaled, centered, or rotated to landscape. The PostScript output can be
written directly to a file or returned through the interpreter.
The following postscript operations are available.
- pathName postscript cget option
- Returns the current value of the postscript option given by
option. Option may be any option described below for the
postscript configure operation.
- pathName postscript configure ?option
value?...
- Queries or modifies the configuration options for
PostScript generation. If option isn't specified, a list describing
the current postscript options for pathName is returned. If
option is specified, but not value, then a list describing
option is returned. If one or more option and value
pairs are specified, then for each pair, the postscript option
option is set to value. The following postscript options are
available.
- -center boolean
- Indicates whether the plot should be centered on the
PostScript page. If boolean is false, the plot will be placed in
the upper left corner of the page. The default is 1.
- -colormap varName
- VarName must be the name of a global array variable
that specifies a color mapping from the X color name to PostScript. Each
element of varName must consist of PostScript code to set a
particular color value (e.g. ``1.0 1.0 0.0 setrgbcolor''). When generating
color information in PostScript, the array variable varName is
checked if an element of the name as the color exists. If so, it uses its
value as the PostScript command to set the color. If this option hasn't
been specified, or if there isn't an entry in varName for a given
color, then it uses the red, green, and blue intensities from the X
color.
- -colormode mode
- Specifies how to output color information. Mode must
be either color (for full color output), gray (convert all colors to their
gray-scale equivalents) or mono (convert foreground colors to black and
background colors to white). The default mode is color.
- -fontmap varName
- VarName must be the name of a global array variable
that specifies a font mapping from the X font name to PostScript. Each
element of varName must consist of a Tcl list with one or two
elements; the name and point size of a PostScript font. When outputting
PostScript commands for a particular font, the array variable
varName is checked to see if an element by the specified font
exists. If there is such an element, then the font information contained
in that element is used in the PostScript output. (If the point size is
omitted from the list, the point size of the X font is used). Otherwise
the X font is examined in an attempt to guess what PostScript font to use.
This works only for fonts whose foundry property is Adobe (such as
Times, Helvetica, Courier, etc.). If all of this fails then the font
defaults to Helvetica-Bold.
- -decorations boolean
- Indicates whether PostScript commands to generate color
backgrounds and 3-D borders will be output. If boolean is false,
the graph will background will be white and no 3-D borders will be
generated. The default is 1.
- -height pixels
- Sets the height of the plot. This lets you print the bar
chart with a height different from the one drawn on the screen. If
pixels is 0, the height is the same as the widget's height. The
default is 0.
- -landscape boolean
- If boolean is true, this specifies the printed area
is to be rotated 90 degrees. In non-rotated output the X-axis of the
printed area runs along the short dimension of the page (``portrait''
orientation); in rotated output the X-axis runs along the long dimension
of the page (``landscape'' orientation). Defaults to 0.
- -maxpect boolean
- Indicates to scale the plot so that it fills the PostScript
page. The aspect ratio of the barchart is still retained. The default is
0.
- -padx pad
- Sets the horizontal padding for the left and right page
borders. The borders are exterior to the plot. Pad can be a list of
one or two screen distances. If pad has two elements, the left
border is padded by the first distance and the right border by the second.
If pad has just one distance, both the left and right borders are
padded evenly. The default is 1i.
- -pady pad
- Sets the vertical padding for the top and bottom page
borders. The borders are exterior to the plot. Pad can be a list of
one or two screen distances. If pad has two elements, the top
border is padded by the first distance and the bottom border by the
second. If pad has just one distance, both the top and bottom
borders are padded evenly. The default is 1i.
- -paperheight pixels
- Sets the height of the postscript page. This can be used to
select between different page sizes (letter, A4, etc). The default height
is 11.0i.
- -paperwidth pixels
- Sets the width of the postscript page. This can be used to
select between different page sizes (letter, A4, etc). The default width
is 8.5i.
- -width pixels
- Sets the width of the plot. This lets you generate a plot
of a width different from that of the widget. If pixels is 0, the
width is the same as the widget's width. The default is 0.
Postscript configuration options may be also be set by the
option
command. The resource name and class are postscript and Postscript
respectively.
option add *Barchart.postscript.Decorations false
option add *Barchart.Postscript.Landscape true
- pathName postscript output ?fileName?
? option value?...
- Outputs a file of encapsulated PostScript. If a
fileName argument isn't present, the command returns the
PostScript. If any option-value pairs are present, they set
configuration options controlling how the PostScript is generated.
Option and value can be anything accepted by the postscript
configure operation above.
MARKER COMPONENTS¶
Markers are simple drawing procedures used to annotate or highlight areas of the
graph. Markers have various types: text strings, bitmaps, images, connected
lines, windows, or polygons. They can be associated with a particular element,
so that when the element is hidden or un-hidden, so is the marker. By default,
markers are the last items drawn, so that data elements will appear in behind
them. You can change this by configuring the
-under option.
Markers, in contrast to elements, don't affect the scaling of the coordinate
axes. They can also have
elastic coordinates (specified by -Inf and Inf
respectively) that translate into the minimum or maximum limit of the axis.
For example, you can place a marker so it always remains in the lower left
corner of the plotting area, by using the coordinates -Inf,-Inf.
The following operations are available for markers.
- pathName marker after markerId
?afterId?
- Changes the order of the markers, drawing the first marker
after the second. If no second afterId argument is specified, the
marker is placed at the end of the display list. This command can be used
to control how markers are displayed since markers are drawn in the order
of this display list.
- pathName marker before markerId
?beforeId?
- Changes the order of the markers, drawing the first marker
before the second. If no second beforeId argument is specified, the
marker is placed at the beginning of the display list. This command can be
used to control how markers are displayed since markers are drawn in the
order of this display list.
- pathName marker bind tagName
?sequence? ? command?
- Associates command with tagName such that
whenever the event sequence given by sequence occurs for a marker
with this tag, command will be invoked. The syntax is similar to
the bind command except that it operates on graph markers, rather
than widgets. See the bind manual entry for complete details on
sequence and the substitutions performed on command before
invoking it.
If all arguments are specified then a new binding is created, replacing any
existing binding for the same sequence and tagName. If the
first character of command is + then command augments an
existing binding rather than replacing it. If no command argument
is provided then the command currently associated with tagName and
sequence (it's an error occurs if there's no such binding) is
returned. If both command and sequence are missing then a
list of all the event sequences for which bindings have been defined for
tagName.
- pathName marker cget option
- Returns the current value of the marker configuration
option given by option. Option may be any option described
below in the configure operation.
- pathName marker configure markerId
?option value?...
- Queries or modifies the configuration options for markers.
If option isn't specified, a list describing the current options
for markerId is returned. If option is specified, but not
value, then a list describing option is returned. If one or
more option and value pairs are specified, then for each
pair, the marker option option is set to value.
The following options are valid for all markers. Each type of marker also
has its own type-specific options. They are described in the sections
below.
- -bindtags tagList
- Specifies the binding tags for the marker. TagList
is a list of binding tag names. The tags and their order will determine
how events for markers are handled. Each tag in the list matching the
current event sequence will have its Tcl command executed. Implicitly the
name of the marker is always the first tag in the list. The default value
is all.
- -coords coordList
- Specifies the coordinates of the marker. CoordList
is a list of graph coordinates. The number of coordinates required is
dependent on the type of marker. Text, image, and window markers need only
two coordinates (an X-Y coordinate). Bitmap markers can take either two or
four coordinates (if four, they represent the corners of the bitmap). Line
markers need at least four coordinates, polygons at least six. If
coordList is "", the marker will not be displayed. The
default is "".
- -element elemName
- Links the marker with the element elemName. The
marker is drawn only if the element is also currently displayed (see the
element's show operation). If elemName is "", the
marker is always drawn. The default is "".
- -hide boolean
- Indicates whether the marker is drawn. If boolean is
true, the marker is not drawn. The default is no.
- -mapx xAxis
- Specifies the X-axis to map the marker's X-coordinates
onto. XAxis must the name of an axis. The default is x.
- -mapy yAxis
- Specifies the Y-axis to map the marker's Y-coordinates
onto. YAxis must the name of an axis. The default is y.
- -name markerId
- Changes the identifier for the marker. The identifier
markerId can not already be used by another marker. If this option
isn't specified, the marker's name is uniquely generated.
- -under boolean
- Indicates whether the marker is drawn below/above data
elements. If boolean is true, the marker is be drawn underneath the
data elements. Otherwise, the marker is drawn on top of the element. The
default is 0.
- -xoffset pixels
- Specifies a screen distance to offset the marker
horizontally. Pixels is a valid screen distance, such as 2 or 1.2i.
The default is 0.
- -yoffset pixels
- Specifies a screen distance to offset the markers
vertically. Pixels is a valid screen distance, such as 2 or 1.2i.
The default is 0.
Marker configuration options may also be set by the
option command. The
resource class is either BitmapMarker, ImageMarker, LineMarker, PolygonMarker,
TextMarker, or WindowMarker, depending on the type of marker. The resource
name is the name of the marker.
option add *Barchart.TextMarker.Foreground white
option add *Barchart.BitmapMarker.Foreground white
option add *Barchart.m1.Background blue
- pathName marker create type ?option
value?...
- Creates a marker of the selected type. Type may be
either text, line, bitmap, image, polygon, or window. This command returns
the marker identifier, used as the markerId argument in the other
marker-related commands. If the -name option is used, this
overrides the normal marker identifier. If the name provided is already
used for another marker, the new marker will replace the old.
- pathName marker delete ?name?...
- Removes one of more markers. The graph will automatically
be redrawn without the marker..
- pathName marker exists markerId
- Returns 1 if the marker markerId exists and 0
otherwise.
- pathName marker names ?pattern?
- Returns the names of all the markers that currently exist.
If pattern is supplied, only those markers whose names match it
will be returned.
- pathName marker type markerId
- Returns the type of the marker given by markerId,
such as line or text. If markerId is not a valid a marker
identifier, "" is returned.
BITMAP MARKERS¶
A bitmap marker displays a bitmap. The size of the bitmap is controlled by the
number of coordinates specified. If two coordinates, they specify the position
of the top-left corner of the bitmap. The bitmap retains its normal width and
height. If four coordinates, the first and second pairs of coordinates
represent the corners of the bitmap. The bitmap will be stretched or reduced
as necessary to fit into the bounding rectangle.
Bitmap markers are created with the marker's
create operation in the
form:
pathName marker create bitmap ?option value?...
There may be many
option-
value pairs, each sets a configuration
options for the marker. These same
option-
value pairs may be
used with the marker's
configure operation.
The following options are specific to bitmap markers:
- -background color
- Same as the -fill option.
- -bitmap bitmap
- Specifies the bitmap to be displayed. If bitmap is
"", the marker will not be displayed. The default is
"".
- -fill color
- Sets the background color of the bitmap. If color is
the empty string, no background will be transparent. The default
background color is "".
- -foreground color
- Same as the -outline option.
- -mask mask
- Specifies a mask for the bitmap to be displayed. This mask
is a bitmap itself, denoting the pixels that are transparent. If
mask is "", all pixels of the bitmap will be drawn. The
default is "".
- -outline color
- Sets the foreground color of the bitmap. The default value
is black.
- -rotate theta
- Sets the rotation of the bitmap. Theta is a real
number representing the angle of rotation in degrees. The marker is first
rotated and then placed according to its anchor position. The default
rotation is 0.0.
IMAGE MARKERS¶
A image marker displays an image. Image markers are created with the marker's
create operation in the form:
pathName marker create image ?option value?...
There may be many
option-
value pairs, each sets a configuration
option for the marker. These same
option-
value pairs may be used
with the marker's
configure operation.
The following options are specific to image markers:
- -anchor anchor
- Anchor tells how to position the image relative to
the positioning point for the image. For example, if anchor is
center then the image is centered on the point; if anchor is n then
the image will be drawn such that the top center point of the rectangular
region occupied by the image will be at the positioning point. This option
defaults to center.
- -image image
- Specifies the image to be drawn. If image is
"", the marker will not be drawn. The default is
"".
LINE MARKERS¶
A line marker displays one or more connected line segments. Line markers are
created with marker's
create operation in the form:
pathName marker create line ?option value?...
There may be many
option-
value pairs, each sets a configuration
option for the marker. These same
option-
value pairs may be used
with the marker's
configure operation.
The following options are specific to line markers:
- -dashes dashList
- Sets the dash style of the line. DashList is a list
of up to 11 numbers that alternately represent the lengths of the dashes
and gaps on the line. Each number must be between 1 and 255. If
dashList is "", the marker line will be solid.
- -fill color
- Sets the background color of the line. This color is used
with striped lines (see the -fdashesIf color is the empty
string, no background color is drawn (the line will be dashed, not
striped). The default background color is "".
- -linewidth pixels
- Sets the width of the lines. The default width is 0.
- -outline color
- Sets the foreground color of the line. The default value is
black.
- -stipple bitmap
- Specifies a stipple pattern used to draw the line, rather
than a solid line. Bitmap specifies a bitmap to use as the stipple
pattern. If bitmap is "", then the line is drawn in a
solid fashion. The default is "".
POLYGON MARKERS¶
A polygon marker displays a closed region described as two or more connected
line segments. It is assumed the first and last points are connected. Polygon
markers are created using the marker
create operation in the form:
pathName marker create polygon ?option value?...
There may be many
option-
value pairs, each sets a configuration
option for the marker. These same
option-
value pairs may be used
with the
marker configure command to change the marker's configuration.
The following options are supported for polygon markers:
- -dashes dashList
- Sets the dash style of the outline of the polygon.
DashList is a list of up to 11 numbers that alternately represent
the lengths of the dashes and gaps on the outline. Each number must be
between 1 and 255. If dashList is "", the outline will be
a solid line.
- -fill color
- Sets the fill color of the polygon. If color is
"", then the interior of the polygon is transparent. The default
is white.
- -linewidth pixels
- Sets the width of the outline of the polygon. If
pixels is zero, no outline is drawn. The default is 0.
- -outline color
- Sets the color of the outline of the polygon. If the
polygon is stippled (see the -stipple option), then this represents
the foreground color of the stipple. The default is black.
- -stipple bitmap
- Specifies that the polygon should be drawn with a stippled
pattern rather than a solid color. Bitmap specifies a bitmap to use
as the stipple pattern. If bitmap is "", then the polygon
is filled with a solid color (if the -fill option is set). The
default is "".
TEXT MARKERS¶
A text marker displays a string of characters on one or more lines of text.
Embedded newlines cause line breaks. They may be used to annotate regions of
the graph. Text markers are created with the
create operation in the
form:
pathName marker create text ?option value?...
There may be many
option-
value pairs, each sets a configuration
option for the text marker. These same
option-
value pairs may be
used with the marker's
configure operation.
The following options are specific to text markers:
- -anchor anchor
- Anchor tells how to position the text relative to
the positioning point for the text. For example, if anchor is
center then the text is centered on the point; if anchor is n then
the text will be drawn such that the top center point of the rectangular
region occupied by the text will be at the positioning point. This default
is center.
- -background color
- Same as the -fill option.
- -font fontName
- Specifies the font of the text. The default is
*-Helvetica-Bold-R-Normal-*-120-*.
- -fill color
- Sets the background color of the text. If color is
the empty string, no background will be transparent. The default
background color is "".
- -foreground color
- Same as the -outline option.
- -justify justify
- Specifies how the text should be justified. This matters
only when the marker contains more than one line of text. Justify
must be left, right, or center. The default is center.
- -outline color
- Sets the color of the text. The default value is
black.
- -padx pad
- Sets the padding to the left and right exteriors of the
text. Pad can be a list of one or two screen distances. If
pad has two elements, the left side of the text is padded by the
first distance and the right side by the second. If pad has just
one distance, both the left and right sides are padded evenly. The default
is 4.
- -pady pad
- Sets the padding above and below the text. Pad can
be a list of one or two screen distances. If pad has two elements,
the area above the text is padded by the first distance and the area below
by the second. If pad is just one distance, both the top and bottom
areas are padded evenly. The default is 4.
- -rotate theta
- Specifies the number of degrees to rotate the text.
Theta is a real number representing the angle of rotation. The
marker is first rotated along its center and is then drawn according to
its anchor position. The default is 0.0.
- -text text
- Specifies the text of the marker. The exact way the text is
displayed may be affected by other options such as -anchor or
-rotate.
WINDOW MARKERS¶
A window marker displays a widget at a given position. Window markers are
created with the marker's
create operation in the form:
pathName marker create window ?option value?...
There may be many
option-
value pairs, each sets a configuration
option for the marker. These same
option-
value pairs may be used
with the marker's
configure command.
The following options are specific to window markers:
- -anchor anchor
- Anchor tells how to position the widget relative to
the positioning point for the widget. For example, if anchor is
center then the widget is centered on the point; if anchor is n
then the widget will be displayed such that the top center point of the
rectangular region occupied by the widget will be at the positioning
point. This option defaults to center.
- -height pixels
- Specifies the height to assign to the marker's window. If
this option isn't specified, or if it is specified as "", then
the window is given whatever height the widget requests internally.
- -width pixels
- Specifies the width to assign to the marker's window. If
this option isn't specified, or if it is specified as "", then
the window is given whatever width the widget requests internally.
- -window pathName
- Specifies the widget to be managed by the barchart.
PathName must be a child of the barchart widget.
GRAPH COMPONENT BINDINGS¶
Specific barchart components, such as elements, markers and legend entries, can
have a command trigger when event occurs in them, much like canvas items in
Tk's canvas widget. Not all event sequences are valid. The only binding events
that may be specified are those related to the mouse and keyboard (such as
Enter,
Leave,
ButtonPress,
Motion, and
KeyPress).
Only one element or marker can be picked during an event. This means, that if
the mouse is directly over both an element and a marker, only the uppermost
component is selected. This isn't true for legend entries. Both a legend entry
and an element (or marker) binding commands will be invoked if both items are
picked.
It is possible for multiple bindings to match a particular event. This could
occur, for example, if one binding is associated with the element name and
another is associated with one of the element's tags (see the
-bindtags
option). When this occurs, all of the matching bindings are invoked. A binding
associated with the element name is invoked first, followed by one binding for
each of the element's bindtags. If there are multiple matching bindings for a
single tag, then only the most specific binding is invoked. A continue command
in a binding script terminates that script, and a break command terminates
that script and skips any remaining scripts for the event, just as for the
bind command.
The
-bindtags option for these components controls addition tag names
which can be matched. Implicitly elements and markers always have tags
matching their names. Setting the value of the
-bindtags option doesn't
change this.
C LANGUAGE API¶
You can manipulate data elements from the C language. There may be situations
where it is too expensive to translate the data values from ASCII strings. Or
you might want to read data in a special file format.
Data can manipulated from the C language using BLT vectors. You specify the X-Y
data coordinates of an element as vectors and manipulate the vector from C.
The barchart will be redrawn automatically after the vectors are updated.
From Tcl, create the vectors and configure the element to use them.
vector X Y
.g element configure line1 -xdata X -ydata Y
To set data points from C, you pass the values as arrays of doubles using the
Blt_ResetVector call. The vector is reset with the new data and at the
next idle point (when Tk re-enters its event loop), the graph will be redrawn
automatically.
#include <tcl.h>
#include <blt.h>
register int i;
Blt_Vector *xVec, *yVec;
double x[50], y[50];
/* Get the BLT vectors "X" and "Y" (created above from Tcl) */
if ((Blt_GetVector(interp, "X", 50, &xVec) != TCL_OK) ||
(Blt_GetVector(interp, "Y", 50, &yVec) != TCL_OK)) {
return TCL_ERROR;
}
for (i = 0; i < 50; i++) {
x[i] = i * 0.02;
y[i] = sin(x[i]);
}
/* Put the data into BLT vectors */
if ((Blt_ResetVector(xVec, x, 50, 50, TCL_VOLATILE) != TCL_OK) ||
(Blt_ResetVector(yVec, y, 50, 50, TCL_VOLATILE) != TCL_OK)) {
return TCL_ERROR;
}
See the
vector manual page for more details.
SPEED TIPS¶
There may be cases where the bar chart needs to be drawn and updated as quickly
as possible. If drawing speed becomes a big problem, here are a few tips to
speed up displays.
- •
- Try to minimize the number of data points. The more data
points looked at, the more work the bar chart must do.
- •
- If your data is generated as floating point values, the
time required to convert the data values to and from ASCII strings can be
significant, especially when there any many data points. You can avoid the
redundant string-to-decimal conversions using the C API to BLT
vectors.
- •
- Don't stipple or dash the element. Solid bars are much
faster.
- •
- If you update data elements frequently, try turning off the
widget's -bufferelements option. When the bar chart is first
displayed, it draws data elements into an internal pixmap. The pixmap acts
as a cache, so that when the bar chart needs to be redrawn again, and the
data elements or coordinate axes haven't changed, the pixmap is simply
copied to the screen. This is especially useful when you are using markers
to highlight points and regions on the bar chart. But if the bar chart is
updated frequently, changing either the element data or coordinate axes,
the buffering becomes redundant.
LIMITATIONS¶
Auto-scale routines do not use requested min/max limits as boundaries when the
axis is logarithmically scaled.
The PostScript output generated for polygons with more than 1500 points may
exceed the limits of some printers (See PostScript Language Reference Manual,
page 568). The work-around is to break the polygon into separate pieces.
KEYWORDS¶
bar chart, widget