ChartDirector 7.1 (C++ Edition)

Heat Map Cell Labels




This example demonstrates adding labels to the cells, adding gaps between cells and using a custom color scale.

This example is similar to Discrete Heat Map, with the following additions:

Source Code Listing

The following is the command line version of the code in "cppdemo/heatmapcelllabels". 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" int main(int argc, char *argv[]) { // The x-axis and y-axis labels const char* xLabels[] = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"}; const int xLabels_size = (int)(sizeof(xLabels)/sizeof(*xLabels)); const char* yLabels[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"}; const int yLabels_size = (int)(sizeof(yLabels)/sizeof(*yLabels)); // Random data for the 10 x 10 cells RanSeries* rand = new RanSeries(2); DoubleArray zData = rand->get2DSeries(xLabels_size, yLabels_size, 0, 100); // We set the middle 5 x 5 cells to NoValue to remove them from the chart for(int x = 3; x < 7; ++x) { for(int y = 3; y < 7; ++y) { ((double*)(zData.data))[y * xLabels_size + x] = Chart::NoValue; } } // Create an XYChart object of size 480 x 540 pixels. XYChart* c = new XYChart(480, 540); // Set the plotarea at (50, 40) and of size 400 x 400 pixels. Set the background, border, and // grid lines to transparent. PlotArea* p = c->setPlotArea(50, 40, 400, 400, -1, -1, Chart::Transparent, Chart::Transparent); // Create a discrete heat map with 10 x 10 cells DiscreteHeatMapLayer* layer = c->addDiscreteHeatMapLayer(zData, xLabels_size); // Set the x-axis labels. Use 8pt Arial Bold font. Set axis stem to transparent, so only the // labels are visible. Set 0.5 offset to position the labels in between the grid lines. Position // the x-axis at the top of the chart. c->xAxis()->setLabels(StringArray(xLabels, xLabels_size)); c->xAxis()->setLabelStyle("Arial Bold", 8); c->xAxis()->setColors(Chart::Transparent, Chart::TextColor); c->xAxis()->setLabelOffset(0.5); c->xAxis()->setTitle("X axis title placeholder", "Arial Bold", 12); c->setXAxisOnTop(); // Set the y-axis labels. Use 8pt Arial Bold font. Set axis stem to transparent, so only the // labels are visible. Set 0.5 offset to position the labels in between the grid lines. Reverse // the y-axis so that the labels are flowing top-down instead of bottom-up. c->yAxis()->setLabels(StringArray(yLabels, yLabels_size)); c->yAxis()->setLabelStyle("Arial Bold", 8); c->yAxis()->setColors(Chart::Transparent, Chart::TextColor); c->yAxis()->setLabelOffset(0.5); c->yAxis()->setTitle("Y axis title placeholder", "Arial Bold", 12); c->yAxis()->setReverse(); // Set a 3-pixel gap between cells layer->setCellGap(3); // Use the z value as the cell label layer->setDataLabelFormat("{z|0}"); // Position the color axis 20 pixels below the plot area and of the width as the plot area. Put // the labels at the bottom side of the color axis. Use 8pt Arial Bold font for the labels. ColorAxis* cAxis = layer->setColorAxis(p->getLeftX(), p->getBottomY() + 20, Chart::TopLeft, p->getWidth(), Chart::Bottom); cAxis->setLabelStyle("Arial Bold", 8); cAxis->setTitle("Color legend title placeholder", "Arial Bold", 12); // Set the color stops and scale of the color axis double colorScale[] = {0, 0x00ff00, 50, 0xffff00, 80, 0xff6600, 100, 0xff0000}; const int colorScale_size = (int)(sizeof(colorScale)/sizeof(*colorScale)); cAxis->setColorScale(DoubleArray(colorScale, colorScale_size)); cAxis->setLinearScale(0, 100, 10); // Output the chart c->makeChart("heatmapcelllabels.png"); //free up resources delete rand; delete c; return 0; }