ChartDirector 6.0 (C++ Edition)

Contour Color Scale


      

This example demonstrates using various coloring for the ContourLayer.

The ChartDirector supports two ways to configure the colors for a contour.

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

Source Code Listing

[The following code is available in "cppdemo/contourcolor". A MFC version of the code is available in "mfcdemo/mfcdemo" (Windows edition only). A QT version of the code is available in "qtdemo/qtdemo".]
#include "chartdir.h"

void createChart(int chartIndex, const char *filename)
{
    // The x and y coordinates of the grid
    double dataX[] = {-4, -3, -2, -1, 0, 1, 2, 3, 4};
    double dataY[] = {-4, -3, -2, -1, 0, 1, 2, 3, 4};

    // Use random numbers for the z values on the XY grid
    RanSeries *r = new RanSeries(99);
    DoubleArray dataZ = r->get2DSeries((int)(sizeof(dataX) / sizeof(dataX[0])), (int)(sizeof(dataY)
         / sizeof(dataY[0])), -0.9, 0.9);

    // Create a XYChart object of size 420 x 360 pixels
    XYChart *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
    ContourLayer *layer = c->addContourLayer(DoubleArray(dataX, (int)(sizeof(dataX) / sizeof(dataX[0
        ]))), DoubleArray(dataY, (int)(sizeof(dataY) / sizeof(dataY[0]))), dataZ);

    // 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.
    ColorAxis *cAxis = layer->setColorAxis(350, 25, Chart::TopLeft, 300, Chart::Right);

    if (chartIndex == 1) {
        // Speicify a color gradient as a list of colors, and use it in the color axis.
        int colorGradient[] = {0x0044cc, 0xffffff, 0x00aa00};
        cAxis->setColorGradient(false, IntArray(colorGradient, (int)(sizeof(colorGradient) / sizeof(
            colorGradient[0]))));
    } else if (chartIndex == 2) {
        // Specify the color scale to use in the color axis
        double 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(DoubleArray(colorScale, (int)(sizeof(colorScale) / sizeof(colorScale[0]
            ))));
    } else if (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.
        double colorScale[] = {0, 0xffff99, 0.2, 0x80cdc1, 0.4, 0x35978f, 0.6, 0x01665e, 0.8,
            0x003c30, 1};
        cAxis->setColorScale(DoubleArray(colorScale, (int)(sizeof(colorScale) / sizeof(colorScale[0]
            ))), 0x66ccff);
    }

    // Output the chart
    c->makeChart(filename);

    //free up resources
    delete r;
    delete c;
}

int main(int argc, char *argv[])
{
    createChart(0, "contourcolor0.png");
    createChart(1, "contourcolor1.png");
    createChart(2, "contourcolor2.png");
    createChart(3, "contourcolor3.png");
    return 0;
}