ChartDirector 7.0 (Perl Edition)

Contour Color Scale


      

This example demonstrates using various color scales for contour charts.

ChartDirector supports two ways to configure the color scale:

This example includes 4 charts to demonstrate both of the above methods.

Source Code Listing

perldemo\contourcolor.pl
#!/usr/bin/perl # The ChartDirector for Perl module is assumed to be in "../lib" use File::Basename; use lib (dirname($0)."/../lib") =~ /(.*)/; use perlchartdir; sub createChart { my $chartIndex = shift; # The x and y coordinates of the grid my $dataX = [-4, -3, -2, -1, 0, 1, 2, 3, 4]; my $dataY = [-4, -3, -2, -1, 0, 1, 2, 3, 4]; # Use random numbers for the z values on the XY grid my $r = new RanSeries(99); my $dataZ = $r->get2DSeries(scalar(@$dataX), scalar(@$dataY), -0.9, 0.9); # Create a XYChart object of size 420 x 360 pixels my $c = new XYChart(420, 360); # Set the plotarea at (30, 25) and of size 300 x 300 pixels. Use semi-transparent grey # (0xdd000000) horizontal and vertical grid lines $c->setPlotArea(30, 25, 300, 300, -1, -1, -1, 0xdd000000, -1); # Set the x-axis and y-axis scale $c->xAxis()->setLinearScale(-4, 4, 1); $c->yAxis()->setLinearScale(-4, 4, 1); # Add a contour layer using the given data my $layer = $c->addContourLayer($dataX, $dataY, $dataZ); # Enable contour label by setting its style to black (000000) 8pt default bold font $layer->setContourLabelStyle("bold", 8, 0x000000); # Set the label to display the value in a CDML block with semi-transparent white (4FFFFFFF) # background and 2 pixels left/right margin and 1 pixel top/bottom margin $layer->setContourLabelFormat("<*block,bgcolor=4FFFFFFF,margin=2 2 1 1*>{value}"); # Move the grid lines in front of the contour layer $c->getPlotArea()->moveGridBefore($layer); # Add a color axis (the legend) in which the top left corner is anchored at (350, 25). Set the # length to 400 300 and the labels on the right side. my $cAxis = $layer->setColorAxis(350, 25, $perlchartdir::TopLeft, 300, $perlchartdir::Right); if ($chartIndex == 1) { # Speicify a color gradient as a list of colors, and use it in the color axis. my $colorGradient = [0x0044cc, 0xffffff, 0x00aa00]; $cAxis->setColorGradient(0, $colorGradient); } elsif ($chartIndex == 2) { # Specify the color scale to use in the color axis my $colorScale = [-1.0, 0x1a9850, -0.75, 0x66bd63, -0.5, 0xa6d96a, -0.25, 0xd9ef8b, 0, 0xfee08b, 0.25, 0xfdae61, 0.5, 0xf46d43, 0.75, 0xd73027, 1]; $cAxis->setColorScale($colorScale); } elsif ($chartIndex == 3) { # Specify the color scale to use in the color axis. Also specify an underflow color 0x66ccff # (blue) for regions that fall below the lower axis limit. my $colorScale = [0, 0xffff99, 0.2, 0x80cdc1, 0.4, 0x35978f, 0.6, 0x01665e, 0.8, 0x003c30, 1 ]; $cAxis->setColorScale($colorScale, 0x66ccff); } # Output the chart $c->makeChart("contourcolor$chartIndex.png"); } createChart(0); createChart(1); createChart(2); createChart(3);