Multi-Bar Chart

This example demonstrates a multi-bar chart, in which bars are clustered. It also demonstrates using alternative plot area background colors, and putting legends internal to the plot area.

A multi-bar chart is a bar chart in which multiple data sets are represented by drawing the bars side by side in a cluster. The multi-bar layer is created by using XYChart.addBarLayer2 with the Side predefined constant.

In this example, the two alternative background colors in the plot area is achieved by specifying two background colors in PlotArea.setBackground. ChartDirector also supports another method PlotArea.setAltBgColor that can be used for both horizontal and vertical alternative background colors.

Note that in this example, a margin is configured at the top of the plot area for the legend keys. This is achieved by using Axis.setMargin.

The following is the command line version of the code in "cppdemo/multibar". 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 data for the bar chart
    double data0[] = {100, 125, 245, 147, 67};
    const int data0_size = (int)(sizeof(data0)/sizeof(*data0));
    double data1[] = {85, 156, 179, 211, 123};
    const int data1_size = (int)(sizeof(data1)/sizeof(*data1));
    double data2[] = {97, 87, 56, 267, 157};
    const int data2_size = (int)(sizeof(data2)/sizeof(*data2));
    const char* labels[] = {"Mon", "Tue", "Wed", "Thu", "Fri"};
    const int labels_size = (int)(sizeof(labels)/sizeof(*labels));

    // Create a XYChart object of size 400 x 240 pixels
    XYChart* c = new XYChart(400, 240);

    // Add a title to the chart using 10 pt Arial font
    c->addTitle("         Average Weekday Network Load", "", 10);

    // Set the plot area at (50, 25) and of size 320 x 180. Use two alternative background colors
    // (0xffffc0 and 0xffffe0)
    c->setPlotArea(50, 25, 320, 180, 0xffffc0, 0xffffe0);

    // Add a legend box at (55, 18) using horizontal layout. Use 8 pt Arial font, with transparent
    // background
    c->addLegend(55, 18, false, "", 8)->setBackground(Chart::Transparent);

    // Add a title to the y-axis
    c->yAxis()->setTitle("Throughput (MBytes Per Hour)");

    // Reserve 20 pixels at the top of the y-axis for the legend box
    c->yAxis()->setTopMargin(20);

    // Set the x axis labels
    c->xAxis()->setLabels(StringArray(labels, labels_size));

    // Add a multi-bar layer with 3 data sets and 3 pixels 3D depth
    BarLayer* layer = c->addBarLayer(Chart::Side, 3);
    layer->addDataSet(DoubleArray(data0, data0_size), 0xff8080, "Server #1");
    layer->addDataSet(DoubleArray(data1, data1_size), 0x80ff80, "Server #2");
    layer->addDataSet(DoubleArray(data2, data2_size), 0x8080ff, "Server #3");

    // Output the chart
    c->makeChart("multibar.png");

    //free up resources
    delete c;

    return 0;
}