ChartDirector 6.0 (C++ Edition)

Arbitrary XY Line Chart




This example demonstrates drawing a line chart with arbitrary x coordinates (not increasing or decreasing in one direction), and adding custom data labels to data points.

The x values of the data points are set into the chart using Layer.setXData. ChartDirector merely joins the points together with lines. It does not require the points to following any particular direction.

Note that this example has special labels for the start and end points of the lines. They are created using Layer.addCustomDataLabel.

Source Code Listing

[The following code is available in "cppdemo/xyline". 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 (x, y) data for the first line
    double dataX0[] = {20, 90, 40, 30, 12};
    double dataY0[] = {10, 40, 75, 54, 20};

    // The (x, y) data for the second line
    double dataX1[] = {10, 40, 75, 54, 60};
    double dataY1[] = {50, 90, 40, 30, 10};

    // Create a XYChart object of size 450 x 450 pixels
    XYChart *c = new XYChart(450, 450);

    // Set the plotarea at (55, 65) and of size 350 x 300 pixels, with white background and a light
    // grey border (0xc0c0c0). Turn on both horizontal and vertical grid lines with light grey color
    // (0xc0c0c0)
    c->setPlotArea(55, 65, 350, 300, 0xffffff, -1, 0xc0c0c0, 0xc0c0c0, -1);

    // Add a legend box at (50, 30) (top of the chart) with horizontal layout. Use 12pt Times Bold
    // Italic font. Set the background and border color to Transparent.
    c->addLegend(50, 30, false, "timesbi.ttf", 12)->setBackground(Chart::Transparent);

    // Add a title to the chart using 18pt Times Bold Itatic font
    c->addTitle("Reaction Path", "timesbi.ttf", 18);

    // Add a title to the y axis using 12pt Arial Bold Italic font
    c->yAxis()->setTitle("Temperature (Celcius)", "arialbi.ttf", 12);

    // Set the y axis line width to 3 pixels
    c->yAxis()->setWidth(3);

    // Add a title to the x axis using 12pt Arial Bold Italic font
    c->xAxis()->setTitle("Pressure (Pa)", "arialbi.ttf", 12);

    // Set the x axis line width to 3 pixels
    c->xAxis()->setWidth(3);

    // Add a red (0xff3333) line layer using dataX0 and dataY0
    LineLayer *layer1 = c->addLineLayer(DoubleArray(dataY0, (int)(sizeof(dataY0) / sizeof(dataY0[0])
        )), 0xff3333, "Compound AAA");
    layer1->setXData(DoubleArray(dataX0, (int)(sizeof(dataX0) / sizeof(dataX0[0]))));

    // Set the line width to 3 pixels
    layer1->setLineWidth(3);

    // Use 9 pixel square symbols for the data points
    layer1->getDataSet(0)->setDataSymbol(Chart::SquareSymbol, 9);

    // Add custom text labels to the first and last point on the scatter plot using Arial Bold font
    layer1->addCustomDataLabel(0, 0, "Start", "arialbd.ttf");
    layer1->addCustomDataLabel(0, 4, "End", "arialbd.ttf");

    // Add a green (0x33ff33) line layer using dataX1 and dataY1
    LineLayer *layer2 = c->addLineLayer(DoubleArray(dataY1, (int)(sizeof(dataY1) / sizeof(dataY1[0])
        )), 0x33ff33, "Compound BBB");
    layer2->setXData(DoubleArray(dataX1, (int)(sizeof(dataX1) / sizeof(dataX1[0]))));

    // Set the line width to 3 pixels
    layer2->setLineWidth(3);

    // Use 11 pixel diamond symbols for the data points
    layer2->getDataSet(0)->setDataSymbol(Chart::DiamondSymbol, 11);

    // Add custom text labels to the first and last point on the scatter plot using Arial Bold font
    layer2->addCustomDataLabel(0, 0, "Start", "arialbd.ttf");
    layer2->addCustomDataLabel(0, 4, "End", "arialbd.ttf");

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

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