Continuous Contour Coloring

The following is the command line version of the code in "cppdemo/smoothcontour". The MFC version of the code is in "mfcdemo/mfcdemo". The Qt Widgets version of the code is in "qtdemo/qtdemo". The QML/Qt Quick version of the code is in "qmldemo/qmldemo".
#include "chartdir.h"
#include <math.h>

int main(int argc, char *argv[])
{
    // The x and y coordinates of the grid
    double dataX[] = {-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    const int dataX_size = (int)(sizeof(dataX)/sizeof(*dataX));
    double dataY[] = {-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    const int dataY_size = (int)(sizeof(dataY)/sizeof(*dataY));

    // The values at the grid points. In this example, we will compute the values using the formula
    // z = Sin(x / 2) * Sin(y / 2).
    const int dataZ_size = dataX_size * dataY_size;
    double dataZ[dataZ_size];
    for(int yIndex = 0; yIndex < dataY_size; ++yIndex) {
        double y = dataY[yIndex];
        for(int xIndex = 0; xIndex < dataX_size; ++xIndex) {
            double x = dataX[xIndex];
            dataZ[yIndex * dataX_size + xIndex] = sin(x / 2.0) * sin(y / 2.0);
        }
    }

    // Create a XYChart object of size 600 x 500 pixels
    XYChart* c = new XYChart(600, 500);

    // Add a title to the chart using 18 points Times New Roman Bold Italic font
    c->addTitle("Nano Lattice Twister Field Intensity        ", "Times New Roman Bold Italic", 18);

    // Set the plotarea at (75, 40) and of size 400 x 400 pixels. Use semi-transparent black
    // (80000000) dotted lines for both horizontal and vertical grid lines
    c->setPlotArea(75, 40, 400, 400, -1, -1, -1, c->dashLineColor(0x80000000, Chart::DotLine), -1);

    // Set x-axis and y-axis title using 12 points Arial Bold Italic font
    c->xAxis()->setTitle("Lattice X Direction (nm)", "Arial Bold Italic", 12);
    c->yAxis()->setTitle("Lattice Y Direction (nm)", "Arial Bold Italic", 12);

    // Set x-axis and y-axis labels to use Arial Bold font
    c->xAxis()->setLabelStyle("Arial Bold");
    c->yAxis()->setLabelStyle("Arial Bold");

    // When auto-scaling, use tick spacing of 40 pixels as a guideline
    c->yAxis()->setTickDensity(40);
    c->xAxis()->setTickDensity(40);

    // Add a contour layer using the given data
    ContourLayer* layer = c->addContourLayer(DoubleArray(dataX, dataX_size), DoubleArray(dataY,
        dataY_size), DoubleArray(dataZ, dataZ_size));

    // Set the contour color to transparent
    layer->setContourColor(Chart::Transparent);

    // Move the grid lines in front of the contour layer
    c->getPlotArea()->moveGridBefore(layer);

    // Add a color axis (the legend) in which the left center point is anchored at (495, 240). Set
    // the length to 370 pixels and the labels on the right side.
    ColorAxis* cAxis = layer->setColorAxis(495, 240, Chart::Left, 370, Chart::Right);

    // Add a bounding box to the color axis using light grey (eeeeee) as the background and dark
    // grey (444444) as the border.
    cAxis->setBoundingBox(0xeeeeee, 0x444444);

    // Add a title to the color axis using 12 points Arial Bold Italic font
    cAxis->setTitle("Twist Pressure (Twist-Volt)", "Arial Bold Italic", 12);

    // Set color axis labels to use Arial Bold font
    cAxis->setLabelStyle("Arial Bold");

    // Use smooth gradient coloring
    cAxis->setColorGradient(true);

    // Output the chart
    c->makeChart("smoothcontour.jpg");

    //free up resources
    delete c;

    return 0;
}