ChartDirector 6.2 (.NET 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

[Windows Forms - C# version] NetWinCharts\CSharpWinCharts\blackroundmeter.cs
using System;
using ChartDirector;

namespace CSharpChartExplorer
{
    public class blackroundmeter : DemoModule
    {
        //Name of demo module
        public string getName() { return "Black Round Meters"; }

        //Number of charts produced in this demo module
        public int getNoOfCharts() { return 6; }

        //Main code for creating charts
        public void createChart(WinChartViewer viewer, int chartIndex)
        {
            // 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(ringGradient, 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("Arial Italic", 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(smoothColorScale);
                // 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(smoothColorScale, 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(smoothColorScale, 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(highLowColorScale);
            } else if (chartIndex == 4) {
                // Add the smooth color scale at radius 44 with 16 pixels outer width
                m.addColorScale(smoothColorScale, 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(stepColorScale);
            }

            // Add a text label centered at (125, 175) with 15pt Arial Italic font
            m.addText(125, 175, "CPU", "Arial Italic", 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.
                ChartDirector.TextBox t = m.addText(125, 232, m.formatValue(value,
                    "<*block,width=50,halign=center*>{value|1}"), "Arial", 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
            viewer.Chart = m;
        }
    }
}

[Windows Forms - VB Version] NetWinCharts\VBNetWinCharts\blackroundmeter.vb
Imports System
Imports Microsoft.VisualBasic
Imports ChartDirector

Public Class blackroundmeter
    Implements DemoModule

    'Name of demo module
    Public Function getName() As String Implements DemoModule.getName
        Return "Black Round Meters"
    End Function

    'Number of charts produced in this demo module
    Public Function getNoOfCharts() As Integer Implements DemoModule.getNoOfCharts
        Return 6
    End Function

    'Main code for creating charts
    Public Sub createChart(viewer As WinChartViewer, chartIndex As Integer) _
        Implements DemoModule.createChart

        ' The value to display on the meter
        Dim value As Double = 72.3

        ' Create an AngularMeter object of size 250 x 250 pixels with transparent background
        Dim m As AngularMeter = New AngularMeter(250, 250, Chart.Transparent)

        ' Set the default text and line colors to white (0xffffff)
        m.setColor(Chart.TextColor, &Hffffff)
        m.setColor(Chart.LineColor, &Hffffff)

        ' Demonstration two different meter scale angles
        If chartIndex Mod 2 = 0 Then
            ' 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)
        End If

        ' Add a black (0x000000) circle with radius 123 pixels as background
        m.addRing(0, 123, &H000000)

        ' Gradient color for the border to make it silver-like
        Dim ringGradient() As Double = {1, &H7f7f7f, 0.5, &Hd6d6d6, 0, &Hffffff, -0.5, &Hd6d6d6, _
            -1, &H7f7f7f}
        ' Add a ring between radii 116 and 122 pixels using the silver gradient as border
        m.addRing(116, 122, m.relativeLinearGradient(ringGradient, 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("Arial Italic", 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.
        Dim smoothColorScale() As Double = {0, &H0000ff, 25, &H0088ff, 50, &H00ff00, 75, &Hdddd00, _
            100, &Hff0000}
        Dim stepColorScale() As Double = {0, &H00aa00, 60, &Hddaa00, 80, &Hcc0000, 100}
        Dim highLowColorScale() As Double = {0, &H00ff00, 70, Chart.Transparent, 100, &Hff0000}

        If chartIndex = 0 Then
            ' Add the smooth color scale at the default position
            m.addColorScale(smoothColorScale)
            ' Add glare up to radius 116 (= region inside border)
            m.addGlare(116)
        ElseIf chartIndex = 1 Then
            ' Add the smooth color scale starting at radius 62 with zero width and ending at radius
            ' 40 with 22 pixels outer width
            m.addColorScale(smoothColorScale, 62, 0, 40, 22)
            ' Add glare up to radius 116 (= region inside border), concave and spanning 190 degrees
            m.addGlare(116, -190)
        ElseIf chartIndex = 2 Then
            ' Add the smooth color scale starting at radius 111 with zero width and ending at radius
            ' 111 with 12 pixels inner width
            m.addColorScale(smoothColorScale, 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)
        ElseIf chartIndex = 3 Then
            ' Add the high/low color scale at the default position
            m.addColorScale(highLowColorScale)
        ElseIf chartIndex = 4 Then
            ' Add the smooth color scale at radius 44 with 16 pixels outer width
            m.addColorScale(smoothColorScale, 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(stepColorScale)
        End If

        ' Add a text label centered at (125, 175) with 15pt Arial Italic font
        m.addText(125, 175, "CPU", "Arial Italic", 15, Chart.TextColor, Chart.Center)

        ' Add a readout to some of the charts as demonstration
        If chartIndex = 0 Or chartIndex = 2 Then
            ' 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.
            Dim t As ChartDirector.TextBox = m.addText(125, 232, m.formatValue(value, _
                "<*block,width=50,halign=center*>{value|1}"), "Arial", 14, &H000000, _
                Chart.BottomCenter)
            t.setBackground(&H99ccff)
            t.setRoundedCorners(5)
        End If

        ' Add a red (0xff0000) pointer at the specified value
        m.addPointer2(value, &Hff0000)

        ' Output the chart
        viewer.Chart = m

    End Sub

End Class

[WPF - C#] NetWPFCharts\blackroundmeter.cs
using System;
using ChartDirector;

namespace CSharpWPFDemo
{
    public class blackroundmeter : DemoModule
    {
        //Name of demo module
        public string getName() { return "Black Round Meters"; }

        //Number of charts produced in this demo module
        public int getNoOfCharts() { return 6; }

        //Main code for creating charts
        public void createChart(WPFChartViewer viewer, int chartIndex)
        {
            // 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(ringGradient, 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("Arial Italic", 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(smoothColorScale);
                // 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(smoothColorScale, 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(smoothColorScale, 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(highLowColorScale);
            } else if (chartIndex == 4) {
                // Add the smooth color scale at radius 44 with 16 pixels outer width
                m.addColorScale(smoothColorScale, 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(stepColorScale);
            }

            // Add a text label centered at (125, 175) with 15pt Arial Italic font
            m.addText(125, 175, "CPU", "Arial Italic", 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.
                ChartDirector.TextBox t = m.addText(125, 232, m.formatValue(value,
                    "<*block,width=50,halign=center*>{value|1}"), "Arial", 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
            viewer.Chart = m;
        }
    }
}

[ASP.NET Web Forms - C# version] NetWebCharts\CSharpASP\blackroundmeter.aspx
(Click here on how to convert this code to code-behind style.)
<%@ Page Language="C#" Debug="true" %>
<%@ Import Namespace="ChartDirector" %>
<%@ Register TagPrefix="chart" Namespace="ChartDirector" Assembly="netchartdir" %>

<!DOCTYPE html>

<script runat="server">

//
// Create chart
//
protected void createChart(WebChartViewer viewer, int chartIndex)
{
    // 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(ringGradient, 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("Arial Italic", 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(smoothColorScale);
        // 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(smoothColorScale, 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(smoothColorScale, 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(highLowColorScale);
    } else if (chartIndex == 4) {
        // Add the smooth color scale at radius 44 with 16 pixels outer width
        m.addColorScale(smoothColorScale, 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(stepColorScale);
    }

    // Add a text label centered at (125, 175) with 15pt Arial Italic font
    m.addText(125, 175, "CPU", "Arial Italic", 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.
        ChartDirector.TextBox t = m.addText(125, 232, m.formatValue(value,
            "<*block,width=50,halign=center*>{value|1}"), "Arial", 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
    viewer.Image = m.makeWebImage(Chart.PNG);
}

//
// Page Load event handler
//
protected void Page_Load(object sender, EventArgs e)
{
    createChart(WebChartViewer0, 0);
    createChart(WebChartViewer1, 1);
    createChart(WebChartViewer2, 2);
    createChart(WebChartViewer3, 3);
    createChart(WebChartViewer4, 4);
    createChart(WebChartViewer5, 5);
}

</script>

<html>
<body>
    <chart:WebChartViewer id="WebChartViewer0" runat="server" />
    <chart:WebChartViewer id="WebChartViewer1" runat="server" />
    <chart:WebChartViewer id="WebChartViewer2" runat="server" />
    <chart:WebChartViewer id="WebChartViewer3" runat="server" />
    <chart:WebChartViewer id="WebChartViewer4" runat="server" />
    <chart:WebChartViewer id="WebChartViewer5" runat="server" />
</body>
</html>

[ASP.NET Web Forms - VB Version] NetWebCharts\VBNetASP\blackroundmeter.aspx
(Click here on how to convert this code to code-behind style.)
<%@ Page Language="VB" Debug="true" %>
<%@ Import Namespace="ChartDirector" %>
<%@ Register TagPrefix="chart" Namespace="ChartDirector" Assembly="netchartdir" %>

<!DOCTYPE html>

<script runat="server">

'
' Create chart
'
Protected Sub createChart(viewer As WebChartViewer, chartIndex As Integer)

    ' The value to display on the meter
    Dim value As Double = 72.3

    ' Create an AngularMeter object of size 250 x 250 pixels with transparent background
    Dim m As AngularMeter = New AngularMeter(250, 250, Chart.Transparent)

    ' Set the default text and line colors to white (0xffffff)
    m.setColor(Chart.TextColor, &Hffffff)
    m.setColor(Chart.LineColor, &Hffffff)

    ' Demonstration two different meter scale angles
    If chartIndex Mod 2 = 0 Then
        ' 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)
    End If

    ' Add a black (0x000000) circle with radius 123 pixels as background
    m.addRing(0, 123, &H000000)

    ' Gradient color for the border to make it silver-like
    Dim ringGradient() As Double = {1, &H7f7f7f, 0.5, &Hd6d6d6, 0, &Hffffff, -0.5, &Hd6d6d6, -1, _
        &H7f7f7f}
    ' Add a ring between radii 116 and 122 pixels using the silver gradient as border
    m.addRing(116, 122, m.relativeLinearGradient(ringGradient, 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("Arial Italic", 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.
    Dim smoothColorScale() As Double = {0, &H0000ff, 25, &H0088ff, 50, &H00ff00, 75, &Hdddd00, _
        100, &Hff0000}
    Dim stepColorScale() As Double = {0, &H00aa00, 60, &Hddaa00, 80, &Hcc0000, 100}
    Dim highLowColorScale() As Double = {0, &H00ff00, 70, Chart.Transparent, 100, &Hff0000}

    If chartIndex = 0 Then
        ' Add the smooth color scale at the default position
        m.addColorScale(smoothColorScale)
        ' Add glare up to radius 116 (= region inside border)
        m.addGlare(116)
    ElseIf chartIndex = 1 Then
        ' Add the smooth color scale starting at radius 62 with zero width and ending at radius 40
        ' with 22 pixels outer width
        m.addColorScale(smoothColorScale, 62, 0, 40, 22)
        ' Add glare up to radius 116 (= region inside border), concave and spanning 190 degrees
        m.addGlare(116, -190)
    ElseIf chartIndex = 2 Then
        ' Add the smooth color scale starting at radius 111 with zero width and ending at radius 111
        ' with 12 pixels inner width
        m.addColorScale(smoothColorScale, 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)
    ElseIf chartIndex = 3 Then
        ' Add the high/low color scale at the default position
        m.addColorScale(highLowColorScale)
    ElseIf chartIndex = 4 Then
        ' Add the smooth color scale at radius 44 with 16 pixels outer width
        m.addColorScale(smoothColorScale, 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(stepColorScale)
    End If

    ' Add a text label centered at (125, 175) with 15pt Arial Italic font
    m.addText(125, 175, "CPU", "Arial Italic", 15, Chart.TextColor, Chart.Center)

    ' Add a readout to some of the charts as demonstration
    If chartIndex = 0 Or chartIndex = 2 Then
        ' 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.
        Dim t As ChartDirector.TextBox = m.addText(125, 232, m.formatValue(value, _
            "<*block,width=50,halign=center*>{value|1}"), "Arial", 14, &H000000, _
            Chart.BottomCenter)
        t.setBackground(&H99ccff)
        t.setRoundedCorners(5)
    End If

    ' Add a red (0xff0000) pointer at the specified value
    m.addPointer2(value, &Hff0000)

    ' Output the chart
    viewer.Image = m.makeWebImage(Chart.PNG)

End Sub

'
' Page Load event handler
'
Protected Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)

    createChart(WebChartViewer0, 0)
    createChart(WebChartViewer1, 1)
    createChart(WebChartViewer2, 2)
    createChart(WebChartViewer3, 3)
    createChart(WebChartViewer4, 4)
    createChart(WebChartViewer5, 5)

End Sub

</script>

<html>
<body>
    <chart:WebChartViewer id="WebChartViewer0" runat="server" />
    <chart:WebChartViewer id="WebChartViewer1" runat="server" />
    <chart:WebChartViewer id="WebChartViewer2" runat="server" />
    <chart:WebChartViewer id="WebChartViewer3" runat="server" />
    <chart:WebChartViewer id="WebChartViewer4" runat="server" />
    <chart:WebChartViewer id="WebChartViewer5" runat="server" />
</body>
</html>

[ASP.NET MVC - Controller] NetMvcCharts\Controllers\BlackroundmeterController.cs
using System;
using System.Web.Mvc;
using ChartDirector;

namespace NetMvcCharts.Controllers
{
    public class BlackroundmeterController : Controller
    {
        //
        // Default Action
        //
        public ActionResult Index()
        {
            ViewBag.Title = "Black Round Meters";

            // This example contains 6 charts.
            ViewBag.Viewer = new RazorChartViewer[6];
            for (int i = 0; i < ViewBag.Viewer.Length; ++i)
                createChart(ViewBag.Viewer[i] = new RazorChartViewer(HttpContext, "chart" + i), i);

            return View("~/Views/Shared/ChartView.cshtml");
        }

        //
        // Create chart
        //
        private void createChart(RazorChartViewer viewer, int chartIndex)
        {
            // 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(ringGradient, 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("Arial Italic", 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(smoothColorScale);
                // 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(smoothColorScale, 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(smoothColorScale, 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(highLowColorScale);
            } else if (chartIndex == 4) {
                // Add the smooth color scale at radius 44 with 16 pixels outer width
                m.addColorScale(smoothColorScale, 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(stepColorScale);
            }

            // Add a text label centered at (125, 175) with 15pt Arial Italic font
            m.addText(125, 175, "CPU", "Arial Italic", 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.
                ChartDirector.TextBox t = m.addText(125, 232, m.formatValue(value,
                    "<*block,width=50,halign=center*>{value|1}"), "Arial", 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
            viewer.Image = m.makeWebImage(Chart.PNG);
        }
    }
}

[ASP.NET MVC - View] NetMvcCharts\Views\Shared\ChartView.cshtml
@{ Layout = null; }

<!DOCTYPE html>

<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>@ViewBag.Title</title>
</head>
<body style="margin:5px 0px 0px 5px">
    <div style="font:bold 18pt verdana;">
        @ViewBag.Title
    </div>
    <hr style="border:solid 1px #000080" />
    <div>
        @{
            if (ViewBag.Viewer is Array)
            {
                // Display multiple charts
                for (int i = 0; i < ViewBag.Viewer.Length; ++i)
                {
                    @:@Html.Raw(ViewBag.Viewer[i].RenderHTML())
                }
            }
            else
            {
                // Display one chart only
                @:@Html.Raw(ViewBag.Viewer.RenderHTML())
            }
        }
    </div>
</body>
</html>