ChartDirector 6.0 (C++ Edition)

Black Round Meters


          

This example demonstrates round meters with black background, silver border and glare effect.

The silver border effect is achieved by using AngularMeter.relativeLinearGradient to create a gradient consisting of varying levels of grey. The gradient is used as the fill color of the border ring created using AngularMeter.addRing. The ring is intentionally configured to be one pixel smaller than the black background circle. This leaves a thin black edge outside of the ring to help it stand out from the white external background.

Glare effect is added to some of the meters using AngularMeter.addGlare. Convex and concave glare at various angles are demonstrated. Glare effect works best in a dark background.

For some meters, a text box is added at the bottom using BaseChart.addText to display the meter value.

Source Code Listing

[The following code is available in "cppdemo/blackroundmeter". 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"

void createChart(int chartIndex, const char *filename)
{
    // The value to display on the meter
    double value = 72.3;

    // Create an AngularMeter object of size 250 x 250 pixels with transparent background
    AngularMeter *m = new AngularMeter(250, 250, Chart::Transparent);

    // Set the default text and line colors to white (0xffffff)
    m->setColor(Chart::TextColor, 0xffffff);
    m->setColor(Chart::LineColor, 0xffffff);

    // Demonstration two different meter scale angles
    if (chartIndex % 2 == 0) {
        // Center at (125, 125), scale radius = 111 pixels, scale angle -140 to +140 degrees
        m->setMeter(125, 125, 111, -140, 140);
    } else {
        // Center at (125, 125), scale radius = 111 pixels, scale angle -180 to +90 degrees
         m->setMeter(125, 125, 111, -180, 90);
    }

    // Add a black (0x000000) circle with radius 123 pixels as background
    m->addRing(0, 123, 0x000000);

    // Gradient color for the border to make it silver-like
    double ringGradient[] = {1, 0x7f7f7f, 0.5, 0xd6d6d6, 0, 0xffffff, -0.5, 0xd6d6d6, -1, 0x7f7f7f};
    // Add a ring between radii 116 and 122 pixels using the silver gradient as border
    m->addRing(116, 122, m->relativeLinearGradient(DoubleArray(ringGradient, (int)(sizeof(
        ringGradient) / sizeof(ringGradient[0]))), 45, 122));

    // Meter scale is 0 - 100, with major/minor/micro ticks every 10/5/1 units
    m->setScale(0, 100, 10, 5, 1);

    // Set the scale label style to 15pt Arial Italic. Set the major/minor/micro tick lengths to
    // 12/9/6 pixels pointing inwards, and their widths to 2/1/1 pixels.
    m->setLabelStyle("ariali.ttf", 15);
    m->setTickLength(-12, -9, -6);
    m->setLineWidth(0, 2, 1, 1);

    // Demostrate different types of color scales and glare effects and putting them at different
    // positions.
    double smoothColorScale[] = {0, 0x0000ff, 25, 0x0088ff, 50, 0x00ff00, 75, 0xdddd00, 100,
        0xff0000};
    double stepColorScale[] = {0, 0x00aa00, 60, 0xddaa00, 80, 0xcc0000, 100};
    double highLowColorScale[] = {0, 0x00ff00, 70, Chart::Transparent, 100, 0xff0000};

    if (chartIndex == 0) {
        // Add the smooth color scale at the default position
        m->addColorScale(DoubleArray(smoothColorScale, (int)(sizeof(smoothColorScale) / sizeof(
            smoothColorScale[0]))));
        // Add glare up to radius 116 (= region inside border)
        m->addGlare(116);
    } else if (chartIndex == 1) {
        // Add the smooth color scale starting at radius 62 with zero width and ending at radius 40
        // with 22 pixels outer width
        m->addColorScale(DoubleArray(smoothColorScale, (int)(sizeof(smoothColorScale) / sizeof(
            smoothColorScale[0]))), 62, 0, 40, 22);
        // Add glare up to radius 116 (= region inside border), concave and spanning 190 degrees
        m->addGlare(116, -190);
    } else if (chartIndex == 2) {
        // Add the smooth color scale starting at radius 111 with zero width and ending at radius
        // 111 with 12 pixels inner width
        m->addColorScale(DoubleArray(smoothColorScale, (int)(sizeof(smoothColorScale) / sizeof(
            smoothColorScale[0]))), 111, 0, 111, -12);
        // Add glare up to radius 116 (= region inside border), concave and spanning 190 degrees and
        // rotated by 45 degrees
        m->addGlare(116, -190, 45);
    } else if (chartIndex == 3) {
        // Add the high/low color scale at the default position
        m->addColorScale(DoubleArray(highLowColorScale, (int)(sizeof(highLowColorScale) / sizeof(
            highLowColorScale[0]))));
    } else if (chartIndex == 4) {
        // Add the smooth color scale at radius 44 with 16 pixels outer width
        m->addColorScale(DoubleArray(smoothColorScale, (int)(sizeof(smoothColorScale) / sizeof(
            smoothColorScale[0]))), 44, 16);
        // Add glare up to radius 116 (= region inside border), concave and spanning 190 degrees and
        // rotated by -45 degrees
        m->addGlare(116, -190, -45);
    } else {
        // Add the step color scale at the default position
        m->addColorScale(DoubleArray(stepColorScale, (int)(sizeof(stepColorScale) / sizeof(
            stepColorScale[0]))));
    }

    // Add a text label centered at (125, 175) with 15pt Arial Italic font
    m->addText(125, 175, "CPU", "ariali.ttf", 15, Chart::TextColor, Chart::Center);

    // Add a readout to some of the charts as demonstration
    if (chartIndex == 0 || chartIndex == 2) {
        // Put the value label center aligned at (125, 232), using black (0x000000) 14pt Arial font
        // on a light blue (0x99ccff) background. Set box width to 50 pixels with 5 pixels rounded
        // corners.
        TextBox *t = m->addText(125, 232, m->formatValue(value,
            "<*block,width=50,halign=center*>{value|1}"), "arial.ttf", 14, 0x000000,
            Chart::BottomCenter);
        t->setBackground(0x99ccff);
        t->setRoundedCorners(5);
    }

    // Add a red (0xff0000) pointer at the specified value
    m->addPointer2(value, 0xff0000);

    // Output the chart
    m->makeChart(filename);

    //free up resources
    delete m;
}

int main(int argc, char *argv[])
{
    createChart(0, "blackroundmeter0.png");
    createChart(1, "blackroundmeter1.png");
    createChart(2, "blackroundmeter2.png");
    createChart(3, "blackroundmeter3.png");
    createChart(4, "blackroundmeter4.png");
    createChart(5, "blackroundmeter5.png");
    return 0;
}