Glass Bar Shading

This example demonstrates using glass shading effect for bars and gradient color for plot area background. It also demonstrates axis labels on both sides of the plot area.

Glass lighting is a complex shading effect that gives a look and feel of tinted glass or semi-transparent plastic material. This effect involves glare and variation of lighting caused by reflection and refraction inside the material.

The gradient plot area background is configured by using BaseChart.linearGradientColor to define the gradient color, then use XYChart.setPlotArea to apply it to the plot area.
The XYChart.setPlotArea also sets the plot area border and grid line colors to white.
The glass shading effect of the bars is defined using Chart::glassEffect, then applied to the bars using Layer.setBorderColor.
XYChart.syncYAxis is used to show two synchronized y-axes on both sides of the plot area.
Axis.setColors is used to set the y-axes to Transparent, so only the axis labels are visible.
The axis label font is set to Arial Bold using Axis.setLabelStyle.

The following is the command line version of the code in "cppdemo/glasslightbar". 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 bar chart
    double data[] = {450, 560, 630, 800, 1100, 1350, 1600, 1950, 2300, 2700};
    const int data_size = (int)(sizeof(data)/sizeof(*data));

    // The labels for the bar chart
    const char* labels[] = {"1996", "1997", "1998", "1999", "2000", "2001", "2002", "2003", "2004",
        "2005"};
    const int labels_size = (int)(sizeof(labels)/sizeof(*labels));

    // Create a XYChart object of size 600 x 360 pixels
    XYChart* c = new XYChart(600, 360);

    // Set the plotarea at (60, 40) and of size 480 x 280 pixels. Use a vertical gradient color from
    // light blue (eeeeff) to deep blue (0000cc) as background. Set border and grid lines to white
    // (ffffff).
    c->setPlotArea(60, 40, 480, 280, c->linearGradientColor(60, 40, 60, 280, 0xeeeeff, 0x0000cc),
        -1, 0xffffff, 0xffffff);

    // Add a title to the chart using 18pt Times Bold Italic font
    c->addTitle("Annual Revenue for Star Tech", "Times New Roman Bold Italic", 18);

    // Add a multi-color bar chart layer using the supplied data. Use glass lighting effect with
    // light direction from the left.
    c->addBarLayer(DoubleArray(data, data_size), IntArray(0, 0))->setBorderColor(Chart::Transparent,
        Chart::glassEffect(Chart::NormalGlare, Chart::Left));

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

    // Show the same scale on the left and right y-axes
    c->syncYAxis();

    // Set the left y-axis and right y-axis title using 10pt Arial Bold font
    c->yAxis()->setTitle("USD (millions)", "Arial Bold", 10);
    c->yAxis2()->setTitle("USD (millions)", "Arial Bold", 10);

    // Set all axes to transparent
    c->xAxis()->setColors(Chart::Transparent);
    c->yAxis()->setColors(Chart::Transparent);
    c->yAxis2()->setColors(Chart::Transparent);

    // Set the label styles of all axes to 8pt Arial Bold font
    c->xAxis()->setLabelStyle("Arial Bold", 8);
    c->yAxis()->setLabelStyle("Arial Bold", 8);
    c->yAxis2()->setLabelStyle("Arial Bold", 8);

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

    //free up resources
    delete c;

    return 0;
}