Dual X-Axis

This example demonstrates a chart with two x-axes and two y-axes.

ChartDirector supports arbitrary number of axes. The first two x and y axes are most commonly used and can be retrieved using XYChart.xAxis, XYChart.xAxis2, XYChart.yAxis and XYChart.yAxis2. These axes are by default positioned at the edges of the plot area.

The key features demonstrated in this example are:

Accessing both the top and bottom x-axes using XYChart.xAxis and XYChart.xAxis2 and set labels to both axes using Axis.setLabels.
Accessing both the primary and secondary y-axes by XYChart.yAxis and XYChart.yAxis2.
Synchronizing the primary and secondary y-axes by using XYChart.syncYAxis.
Use multiple x-axis label formats by using Axis.setMultiFormat.
Use Axis.setTickLength and Axis.setTickLength2 to control the axis ticks length and orientation (that is, internal or external to the chart)

The following is the command line version of the code in "cppdemo/dualxaxis". 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 data0[] = {42, 49, 33, 38, 51, 46, 29, 41, 44, 57, 59, 52, 37, 34, 51, 56, 56, 60, 70,
        76, 63, 67, 75, 64, 51};
    const int data0_size = (int)(sizeof(data0)/sizeof(*data0));
    double data1[] = {50, 55, 47, 34, 42, 49, 63, 62, 73, 59, 56, 50, 64, 60, 67, 67, 58, 59, 73,
        77, 84, 82, 80, 84, 98};
    const int data1_size = (int)(sizeof(data1)/sizeof(*data1));

    // The labels for the bottom x axis. Note the "-" means a minor tick.
    const char* labels0[] = {"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 labels0_size = (int)(sizeof(labels0)/sizeof(*labels0));

    // The labels for the top x axis. Note that "-" means a minor tick.
    const char* labels1[] = {"Jun 3\n12", "13", "14", "15", "16", "17", "18", "19", "20", "21",
        "22", "23", "Jun 4\n0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12"};
    const int labels1_size = (int)(sizeof(labels1)/sizeof(*labels1));

    // Create a XYChart object of size 310 x 310 pixels
    XYChart* c = new XYChart(310, 310);

    // Set the plotarea at (50, 50) and of size 200 x 200 pixels
    c->setPlotArea(50, 50, 200, 200);

    // Add a title to the primary (left) y axis
    c->yAxis()->setTitle("US Dollars");

    // Set the tick length to -4 pixels (-ve means ticks inside the plot area)
    c->yAxis()->setTickLength(-4);

    // Add a title to the secondary (right) y axis
    c->yAxis2()->setTitle("HK Dollars (1 USD = 7.8 HKD)");

    // Set the tick length to -4 pixels (-ve means ticks inside the plot area)
    c->yAxis2()->setTickLength(-4);

    // Synchronize the y-axis such that y2 = 7.8 x y1
    c->syncYAxis(7.8);

    // Add a title to the bottom x axis
    c->xAxis()->setTitle("Hong Kong Time");

    // Set the labels on the x axis.
    c->xAxis()->setLabels(StringArray(labels0, labels0_size));

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

    // Set the major tick length to -4 pixels and minor tick length to -2 pixels (-ve means ticks
    // inside the plot area)
    c->xAxis()->setTickLength(-4, -2);

    // Set the distance between the axis labels and the axis to 6 pixels
    c->xAxis()->setLabelGap(6);

    // Add a title to the top x-axis
    c->xAxis2()->setTitle("New York Time");

    // Set the labels on the x axis.
    c->xAxis2()->setLabels(StringArray(labels1, labels1_size));

    // Display 1 out of 3 labels on the x-axis. Show minor ticks for remaining labels.
    c->xAxis2()->setLabelStep(3, 1);

    // Set the major tick length to -4 pixels and minor tick length to -2 pixels (-ve means ticks
    // inside the plot area)
    c->xAxis2()->setTickLength(-4, -2);

    // Set the distance between the axis labels and the axis to 6 pixels
    c->xAxis2()->setLabelGap(6);

    // Add a line layer to the chart with a line width of 2 pixels
    c->addLineLayer(DoubleArray(data0, data0_size), -1, "Red Transactions")->setLineWidth(2);

    // Add an area layer to the chart with no area boundary line
    c->addAreaLayer(DoubleArray(data1, data1_size), -1, "Green Transactions")->setLineWidth(0);

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

    //free up resources
    delete c;

    return 0;
}