ChartDirector Ver 4.1 (C++ Edition)

Y Zone Coloring




This example demonstrates using y zone colors - colors that change at certain y value thresholds.

In this example, a y zone color is used as the fill color of an area layer, so that the area fill color changes above a certain threshold.

Y zone colors are created using Layer.yZoneColor. You can use a y zone color in any ChartDirector API that expects a color. For instance, you can use a y zone color as background color, fill color of data sets, line color, etc.

A single y zone color can support one threshold value and change between two colors. The two colors can be any colors, including another y zone color. You may create y zone colors with multiple thresholds by cascading multiple y zone colors this way.

Source Code Listing

[The following code is available in "cppdemo/yzonecolor". A MFC version of the code is available in "mfcdemo" (Windows edition only).]
#include "chartdir.h"

int main(int argc, char *argv[])
{
    // The data for the chart
    double data[] = {30, 28, 40, 55, 75, 68, 54, 60, 50, 62, 75, 65, 75, 89, 60, 55,
        53, 35, 50, 66, 56, 48, 52, 65, 62};

    // The labels for the chart
    const char *labels[] = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
        "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23",
        "24"};

    // Create a XYChart object of size 500 x 300 pixels, with a pale yellow
    // (0xffffc0) background, a black border, and 1 pixel 3D border effect
    XYChart *c = new XYChart(500, 300, 0xffffc0, 0x000000, 1);

    // Set the plotarea at (55, 50) and of size 420 x 205 pixels, with white
    // background. Turn on both horizontal and vertical grid lines with light grey
    // color (0xc0c0c0)
    c->setPlotArea(55, 50, 420, 205, 0xffffff)->setGridColor(0xc0c0c0, 0xc0c0c0);

    // Add a legend box at (55, 25) (top of the chart) with horizontal layout. Use 8
    // pts Arial font. Set the background and border color to Transparent.
    LegendBox *legendBox = c->addLegend(55, 25, false, "", 8);
    legendBox->setBackground(Chart::Transparent);

    // Add keys to the legend box to explain the color zones
    legendBox->addKey("Normal Zone", 0x8033FF33);
    legendBox->addKey("Alert Zone", 0x80FF3333);

    // Add a title box to the chart using 13 pts Arial Bold Italic font. The title is
    // in CDML and includes embedded images for highlight. The text is white
    // (0xffffff) on a black background, with a 1 pixel 3D border.
    c->addTitle(
        "<*block,valign=absmiddle*><*img=star.png*><*img=star.png*> Y Zone Color "
        "Demo <*img=star.png*><*img=star.png*><*/*>", "arialbi.ttf", 13, 0xffffff
        )->setBackground(0x000000, -1, 1);

    // Add a title to the y axis
    c->yAxis()->setTitle("Energy Concentration (KJ per liter)");

    // Set the labels on the x axis.
    c->xAxis()->setLabels(StringArray(labels, sizeof(labels)/sizeof(labels[0])));

    // Display 1 out of 3 labels on the x-axis.
    c->xAxis()->setLabelStep(3);

    // Add a title to the x axis using CDML
    c->xAxis()->setTitle(
        "<*block,valign=absmiddle*><*img=clock.png*>  Elapsed Time (hour)<*/*>");

    // Set the axes width to 2 pixels
    c->xAxis()->setWidth(2);
    c->yAxis()->setWidth(2);

    // Add an area layer to the chart. The area is using a y zone color, where the
    // color is semi-transparent green below 60, and semi-transparent red above 60.
    c->addAreaLayer(DoubleArray(data, sizeof(data)/sizeof(data[0])), c->yZoneColor(
        60, 0x8033FF33, 0x80FF3333));

    // Add a custom CDML text at the bottom right of the plot area as the logo
    c->addText(475, 255,
        "<*block,valign=absmiddle*><*img=small_molecule.png*> <*block*>"
        "<*font=timesbi.ttf,size=10,color=804040*>Molecular\nEngineering<*/*>"
        )->setAlignment(Chart::BottomRight);

    // output the chart
    c->makeChart("yzonecolor.png");

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