ChartDirector Ver 4.1 (C++ Edition)

Simple Rose Chart




This example demonstrates how to create a rose chart.

A rose chart is basically a polar chart with sectors of variable radius. This can be achieved by creating a PolarChart object as the graph paper, and adding sector zones on it using AngularAxis.addZone.

To enable auto-scale of the axis, in this example, we also add the radius data to a transparent line layer using PolarChart.addLineLayer. The line layer has no visible effect, but it causes the radial axis to auto-scale so that it covers the radius data.

Source Code Listing

[The following code is available in "cppdemo/rose". A MFC version of the code is available in "mfcdemo" (Windows edition only).]
#include "chartdir.h"

int main(int argc, char *argv[])
{
    // Data for the chart
    double data[] = {9.4, 1.8, 2.1, 2.3, 3.5, 7.7, 8.8, 6.1, 5.0, 3.1, 6.0, 4.3, 5.1,
        2.6, 1.5, 2.2, 5.1, 4.3, 4.0, 9.0, 1.7, 8.8, 9.9, 9.5};
    double angles[] = {0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180, 195,
        210, 225, 240, 255, 270, 285, 300, 315, 330, 345};

    // Create a PolarChart object of size 460 x 460 pixels, with a silver background
    // and a 1 pixel 3D border
    PolarChart *c = new PolarChart(460, 460, Chart::silverColor(), 0x000000, 1);

    // Add a title to the chart at the top left corner using 15pts Arial Bold Italic
    // font. Use white text on deep blue background.
    c->addTitle("Polar Vector Chart Demonstration", "arialbi.ttf", 15, 0xffffff
        )->setBackground(0x000080);

    // Set plot area center at (230, 240) with radius 180 pixels and white background
    c->setPlotArea(230, 240, 180, 0xffffff);

    // Set the grid style to circular grid
    c->setGridStyle(false);

    // Set angular axis as 0 - 360, with a spoke every 30 units
    c->angularAxis()->setLinearScale(0, 360, 30);

    // Add sectors to the chart as sector zones
    int i;
    for(i = 0; i < sizeof(data) / sizeof(data[0]); ++i) {
        c->angularAxis()->addZone(angles[i], angles[i] + 15, 0, data[i], 0x33ff33,
            0x008000);
    }

    // Add an Transparent invisible layer to ensure the axis is auto-scaled using the
    // data
    c->addLineLayer(DoubleArray(data, sizeof(data)/sizeof(data[0])),
        Chart::Transparent);

    // output the chart
    c->makeChart("rose.png");

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