ChartDirector 6.0 (C++ Edition)

Percentage Bar Chart




This example demonstrates creating a percentage bar chart with a legend box. It also demonstrates gradient background color, rounded frame, soft drop shadow, and using CDML to include custom icons in the legend box.

A percentage bar chart is like a stacked bar chart, except the bars are individually scaled so that they stacked up to 100.

The key features demonstrated in this example are:

Note that by default, the data label format is {percent}% (showing the percentage) for a percentage bar layer, as opposed to {value} (showing the data value) for other types of bar layer. The data label format can be modified using Layer.setDataLabelFormat.

Source Code Listing

[The following code is available in "cppdemo/percentbar". 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"

int main(int argc, char *argv[])
{
    // The data for the bar chart
    double data0[] = {100, 125, 245, 147, 67};
    double data1[] = {85, 156, 179, 211, 123};
    double data2[] = {97, 87, 56, 267, 157};

    // The labels for the bar chart
    const char *labels[] = {"Mon", "Tue", "Wed", "Thu", "Fri"};

    // Create a XYChart object of size 500 x 320 pixels. Use a vertical gradient color from pale
    // blue (e8f0f8) to sky blue (aaccff) spanning half the chart height as background. Set border
    // to blue (88aaee). Use rounded corners. Enable soft drop shadow.
    XYChart *c = new XYChart(500, 320);
    c->setBackground(c->linearGradientColor(0, 0, 0, c->getHeight() / 2, 0xe8f0f8, 0xaaccff),
        0x88aaee);
    c->setRoundedFrame();
    c->setDropShadow();

    // Add a title to the chart using 15 points Arial Italic. Set top/bottom margins to 15 pixels.
    TextBox *title = c->addTitle("Weekly Product Sales", "ariali.ttf", 15);
    title->setMargin(0, 0, 15, 15);

    // Tentatively set the plotarea to 50 pixels from the left edge, and to just under the title.
    // Set the width to 60% of the chart width, and the height to 50 pixels from the bottom edge.
    // Use pale blue (e8f0f8) background, transparent border, and grey (aaaaaa) grid lines.
    c->setPlotArea(50, title->getHeight(), c->getWidth() * 6 / 10, c->getHeight() -
        title->getHeight() - 50, 0xe8f0f8, -1, Chart::Transparent, 0xaaaaaa);

    // Add a legend box where the top-right corner is anchored at 10 pixels from the right edge, and
    // just under the title. Use vertical layout and 8 points Arial font.
    LegendBox *legendBox = c->addLegend(c->getWidth() - 10, title->getHeight(), true, "arial.ttf", 8
        );
    legendBox->setAlignment(Chart::TopRight);

    // Set the legend box background and border to transparent
    legendBox->setBackground(Chart::Transparent, Chart::Transparent);

    // Set the legend box icon size to 16 x 32 pixels to match with custom icon size
    legendBox->setKeySize(16, 32);

    // Set axes to transparent
    c->xAxis()->setColors(Chart::Transparent);
    c->yAxis()->setColors(Chart::Transparent);

    // Set the labels on the x axis
    c->xAxis()->setLabels(StringArray(labels, (int)(sizeof(labels) / sizeof(labels[0]))));

    // Add a percentage bar layer
    BarLayer *layer = c->addBarLayer(Chart::Percentage);

    // Add the three data sets to the bar layer, using icons images with labels as data set names
    layer->addDataSet(DoubleArray(data0, (int)(sizeof(data0) / sizeof(data0[0]))), 0x66aaee,
        "<*block,valign=absmiddle*><*img=service.png*> Service<*/*>");
    layer->addDataSet(DoubleArray(data1, (int)(sizeof(data1) / sizeof(data1[0]))), 0xeebb22,
        "<*block,valign=absmiddle*><*img=software.png*> Software<*/*>");
    layer->addDataSet(DoubleArray(data2, (int)(sizeof(data2) / sizeof(data2[0]))), 0xcc88ff,
        "<*block,valign=absmiddle*><*img=computer.png*> Hardware<*/*>");

    // Use soft lighting effect with light direction from top
    layer->setBorderColor(Chart::Transparent, Chart::softLighting(Chart::Top));

    // Enable data label at the middle of the the bar
    layer->setDataLabelStyle()->setAlignment(Chart::Center);

    // For a vertical stacked chart with positive data only, the last data set is always on top.
    // However, in a vertical legend box, the last data set is at the bottom. This can be reversed
    // by using the setLegend method.
    layer->setLegend(Chart::ReverseLegend);

    // Adjust the plot area size, such that the bounding box (inclusive of axes) is 15 pixels from
    // the left edge, just below the title, 10 pixels to the right of the legend box, and 15 pixels
    // from the bottom edge.
    c->packPlotArea(15, title->getHeight(), c->layoutLegend()->getLeftX() - 10, c->getHeight() - 15)
        ;

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

    //free up resources
    delete c;
    return 0;
}