ChartDirector 7.0 (C++ Edition)

Surface Color Scale


      

This example demonstrates using various color scales for surface 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

[The following code is available in "cppdemo/surfacecolor". 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};
    const int dataX_size = (int)(sizeof(dataX)/sizeof(*dataX));
    double dataY[] = {-4, -3, -2, -1, 0, 1, 2, 3, 4};
    const int dataY_size = (int)(sizeof(dataY)/sizeof(*dataY));

    // Use random numbers for the z values on the XY grid
    RanSeries* r = new RanSeries(99);
    DoubleArray dataZ = r->get2DSeries(dataX_size, dataY_size, -0.9, 0.9);

    // Create a SurfaceChart object of size 460 x 460 pixels with white (0xffffff) background and
    // grey (0x888888) border
    SurfaceChart* c = new SurfaceChart(460, 460, 0xffffff, 0x888888);

    // Set the surface data
    c->setData(DoubleArray(dataX, dataX_size), DoubleArray(dataY, dataY_size), dataZ);

    // Add a color axis (the legend) in at the top center of the chart, with labels at the bottom.
    // Set the axis to flat style.
    ColorAxis* cAxis = c->setColorAxis(c->getWidth() / 2, 15, Chart::Top, 250, Chart::Bottom);
    cAxis->setTitle("Color Axis");
    cAxis->setAxisBorder(Chart::Transparent, 0);

    // By default, the color axis is synchronized with the z-axis. The following code remove the
    // synchronization so that the color axis will auto-scale independently. Set the auto-scale
    // minimum tick spacing to 20 pixels.
    cAxis->syncAxis(0);
    cAxis->setTickDensity(20);

    if (chartIndex == 1) {
        // Speicify a color gradient as a list of colors, and use it in the color axis.
        int colorGradient[] = {0x0044cc, 0xffffff, 0x00aa00};
        const int colorGradient_size = (int)(sizeof(colorGradient)/sizeof(*colorGradient));
        cAxis->setColorGradient(false, IntArray(colorGradient, colorGradient_size));
    } 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};
        const int colorScale_size = (int)(sizeof(colorScale)/sizeof(*colorScale));
        cAxis->setColorScale(DoubleArray(colorScale, colorScale_size));
    } 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};
        const int colorScale_size = (int)(sizeof(colorScale)/sizeof(*colorScale));
        cAxis->setColorScale(DoubleArray(colorScale, colorScale_size), 0x66ccff);
    }

    // Set the center of the plot region at (230, 250), and set width x depth x height to 240 x 240
    // x 170 pixels
    c->setPlotRegion(230, 250, 240, 240, 170);

    // Set the plot region wall thichness to 3 pixels
    c->setWallThickness(3);

    // Set the elevation and rotation angles to 45 degrees
    c->setViewAngle(45, 45);

    // Set the perspective level to 20
    c->setPerspective(20);

    // Spline interpolate data to a 50 x 50 grid for a smooth surface
    c->setInterpolation(50, 50);

    // Set the axis title
    c->xAxis()->setTitle("X-Axis", "arialbd.ttf", 10);
    c->yAxis()->setTitle("Y-Axis", "arialbd.ttf", 10);
    c->zAxis()->setTitle("Z Axis", "arialbd.ttf", 10);

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

    //free up resources
    delete r;
    delete c;

}

int main(int argc, char *argv[])
{
    createChart(0, "surfacecolor0.png");
    createChart(1, "surfacecolor1.png");
    createChart(2, "surfacecolor2.png");
    createChart(3, "surfacecolor3.png");
    return 0;
}