This example illustrates how to control scaling of an axis.
By default, ChartDirector will auto-scaled all axes. The
Axis.setAutoScale method controls the top extension, bottom extension and the zero affinity parameters that ChartDirector uses during auto-scaling. The first three charts demonstrates the effects of different top/bottom extensions. (Please refer to
Axis.setAutoScale on what these parameters mean.)
The fourth chart demonstrates that one could exclude a segment on the ends of an axis from scaling using
Axis.setMargin.
The fifth chart demonstrates using manual scaling instead of auto-scaling. A manual linear scale can be configured using
Axis.setLinearScale or
Axis.setLinearScale2. ChartDirector also supports
Axis.setLogScale,
Axis.setLogScale2,
Axis.setDateScale and
Axis.setDateScale2 for configuring manual log and date scales.
[File: perldemo/axisscale.pl] (The CGI version is available as "perldemo_cgi/axisscale.pl".)
#!/usr/bin/perl
use perlchartdir;
sub createChart
{
my $img = shift;
#The data for the chart
my $data = [5.5, 3.5, -3.7, 1.7, -1.4, 3.3];
my $labels = ["Jan", "Feb", "Mar", "Apr", "May", "Jun"];
#Create a XYChart object of size 200 x 180 pixels
my $c = new XYChart(200, 180);
#Set the plot area at (30, 20) and of size 140 x 130 pixels
$c->setPlotArea(30, 20, 140, 130);
#Configure the axis as according to the input parameter
if ($img == "0") {
$c->addTitle("No Axis Extension", "arial.ttf", 8);
} elsif ($img == "1") {
$c->addTitle("Top/Bottom Extensions = 0/0", "arial.ttf", 8);
#Reserve 20% margin at top of plot area when auto-scaling
$c->yAxis()->setAutoScale(0, 0);
} elsif ($img == "2") {
$c->addTitle("Top/Bottom Extensions = 0.2/0.2", "arial.ttf", 8);
#Reserve 20% margin at top and bottom of plot area when auto-scaling
$c->yAxis()->setAutoScale(0.2, 0.2);
} elsif ($img == "3") {
$c->addTitle("Axis Top Margin = 15", "arial.ttf", 8);
#Reserve 15 pixels at top of plot area
$c->yAxis()->setMargin(15);
} else {
$c->addTitle("Manual Scale -5 to 10", "arial.ttf", 8);
#Set the y axis to scale from -5 to 10, with ticks every 5 units
$c->yAxis()->setLinearScale(-5, 10, 5);
}
#Set the labels on the x axis
$c->xAxis()->setLabels($labels);
#Add a color bar layer using the given data. Use a 1 pixel 3D border for the
#bars.
$c->addBarLayer3($data)->setBorderColor(-1, 1);
#output the chart
$c->makeChart("axisscale$img.png")
}
createChart(0);
createChart(1);
createChart(2);
createChart(3);
createChart(4);
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