Marks and Zones (2)

This example demonstrates adding marks and zones to the chart, and positioning mark labels.

The chart in the example consists of three mark lines (one horizontal and two vertical) and one vertical zone. The mark lines are created using Axis.addMark. The zone is created using Axis.addZone.

By default, mark labels will be drawn as axis labels. In this example, the label of the red mark line is moved to the top center of the mark line using TextBox.setAlignment with TopCenter alignment.

Similarly, the labels for the brown mark lines are moved to the left and right sides of the mark lines, with the text rotated by 90 degrees. This is achieved by using TextBox.setAlignment with Left and Right alignments, and using TextBox.setFontAngle.

The following is the command line version of the code in "cppdemo/markzone2". 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 chart
    double data[] = {50, 55, 47, 34, 42, 49, 63, 62, 73, 59, 56, 50, 64, 60, 67, 67, 58, 59, 73, 77,
        84, 82, 80, 84, 89};
    const int data_size = (int)(sizeof(data)/sizeof(*data));

    // The labels for the chart. Note the "-" means a minor tick.
    const char* labels[] = {"0\nJun 4", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
        "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "0\nJun 5"};
    const int labels_size = (int)(sizeof(labels)/sizeof(*labels));

    // Create a XYChart object of size 400 x 270 pixels
    XYChart* c = new XYChart(400, 270);

    // Set the plotarea at (80, 25) and of size 300 x 200 pixels. Use alternate color background
    // (0xeeeeee) and (0xffffff). Set border and grid colors to grey (0xc0c0c0).
    c->setPlotArea(50, 25, 300, 200, 0xeeeeee, 0xffffff, 0xc0c0c0, 0xc0c0c0, 0xc0c0c0);

    // Add a title to the chart using 14pt Times Bold Italic font
    c->addTitle("Server Monitor", "Times New Roman Bold Italic", 14);

    // Add a title to the y axis
    c->yAxis()->setTitle("Server Load (MBytes)");

    // Set the y axis width to 2 pixels
    c->yAxis()->setWidth(2);

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

    // Display 1 out of 3 labels on the x-axis. Show minor ticks for remaining labels.
    c->xAxis()->setLabelStep(3, 1);

    // Set the x axis width to 2 pixels
    c->xAxis()->setWidth(2);

    // Add a horizontal red (0x800080) mark line at y = 80
    Mark* yMark = c->yAxis()->addMark(80, 0xff0000, "Critical Threshold Set Point");

    // Set the mark line width to 2 pixels
    yMark->setLineWidth(2);

    // Put the mark label at the top center of the mark line
    yMark->setAlignment(Chart::TopCenter);

    // Add an orange (0xffcc66) zone from x = 18 to x = 20
    c->xAxis()->addZone(18, 20, 0xffcc66);

    // Add a vertical brown (0x995500) mark line at x = 18
    Mark* xMark1 = c->xAxis()->addMark(18, 0x995500, "Backup Start");

    // Set the mark line width to 2 pixels
    xMark1->setLineWidth(2);

    // Put the mark label at the left of the mark line
    xMark1->setAlignment(Chart::Left);

    // Rotate the mark label by 90 degrees so it draws vertically
    xMark1->setFontAngle(90);

    // Add a vertical brown (0x995500) mark line at x = 20
    Mark* xMark2 = c->xAxis()->addMark(20, 0x995500, "Backup End");

    // Set the mark line width to 2 pixels
    xMark2->setLineWidth(2);

    // Put the mark label at the right of the mark line
    xMark2->setAlignment(Chart::Right);

    // Rotate the mark label by 90 degrees so it draws vertically
    xMark2->setFontAngle(90);

    // Add a green (0x00cc00) line layer with line width of 2 pixels
    c->addLineLayer(DoubleArray(data, data_size), 0x00cc00)->setLineWidth(2);

    // Output the chart
    c->makeChart("markzone2.png");

    //free up resources
    delete c;

    return 0;
}