ChartDirector 6.0 (C++ Edition)

Compact Line Chart




This example extends the Simple Line Chart example by decorating the chart using a number of chart formatting features.

In this example, random data is used. They are generated using a ChartDirector utility class RanTable. RanTable simulates a database table with the cells filled with random numbers. The columns of the table can be retrieved as arrays using RanTable.getCol.

Source Code Listing

[The following code is available in "cppdemo/compactline". 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[])
{
    //
    //    We use a random number generator to simulate the data from 9:30am to 4:30pm with one data
    //    point every 4 minutes. The total number of points during that period is 106.  (7 hours x
    //    15 points/hour + 1)
    //
    int noOfPoints = 106;

    // Assume we have not reached the end of the day yet, and only 85 points are available. Create a
    // random table object of 1 col x 85 rows, using 9 as seed.
    RanTable *rantable = new RanTable(9, 1, 85);

    // Set the 1st column to start with 1800 and with random delta from -5 to 5.
    rantable->setCol(0, 1800, -5, 5);

    // Get the data as the 1st column of the random table
    DoubleArray data = rantable->getCol(0);

    // The x-axis labels for the chart
    const char *labels[] = {"-", "10am", "-", " ", "-", "12am", "-", " ", "-", "2pm", "-", " ", "-",
        "4pm", "-"};

    //
    //    Now we obtain the data into arrays, we can start to draw the chart using ChartDirector
    //

    // Create a XYChart object of size 180 x 180 pixels with a blue background (0x9c9cce)
    XYChart *c = new XYChart(180, 180, 0x9c9cce);

    // Add titles to the top and bottom of the chart using 7.5pt Arial font. The text is white
    // 0xffffff on a deep blue 0x31319C background.
    c->addTitle(Chart::Top, "STAR TECH INDEX  2003-01-28", "arial.ttf", 7.5, 0xffffff, 0x31319c);
    c->addTitle(Chart::Bottom, "LATEST  STI:1809.41 (+14.51)", "arial.ttf", 7.5, 0xffffff, 0x31319c)
        ;

    // Set the plotarea at (31, 21) and of size 145 x 124 pixels, with a pale yellow (0xffffc8)
    // background.
    c->setPlotArea(31, 21, 145, 124, 0xffffc8);

    // Add custom text at (176, 21) (top right corner of plotarea) using 11pt Times Bold Italic
    // font/red (0xc09090) color
    c->addText(176, 21, "Chart Demo", "timesbi.ttf", 11, 0xc09090)->setAlignment(Chart::TopRight);

    // Use 7.5pt Arial as the y axis label font
    c->yAxis()->setLabelStyle("", 7.5);

    // Set the labels on the x axis by spreading the labels evenly between the first point (index =
    // 0) and the last point (index = noOfPoints - 1)
    c->xAxis()->setLinearScale(0, noOfPoints - 1, StringArray(labels, (int)(sizeof(labels) / sizeof(
        labels[0]))));

    // Use 7.5pt Arial as the x axis label font
    c->xAxis()->setLabelStyle("", 7.5);

    // Add a deep blue (0x000080) line layer to the chart
    c->addLineLayer(data, 0x000080);

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

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