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Color.A Property

Gets the alpha component value of this Color structure.

Namespace:  System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

public byte A { get; }

Property Value

Type: System.Byte
The alpha component value of this Color.

The color of each pixel is represented as a 32-bit number: 8 bits each for alpha, red, green, and blue (ARGB). The alpha component specifies the transparency of the color: 0 is fully transparent, and 255 is fully opaque. Likewise, an A value of 255 represents an opaque color. An A value from 1 through 254 represents a semitransparent color. The color becomes more opaque as A approaches 255.

The following code example demonstrates the A, R, G, and B properties of a Color, and the Implicit member.

This example is designed to be used with a Windows Form. Paste the code into the form and call the ShowPropertiesOfSlateBlue method from the form's Paint event-handling method, passing e as PaintEventArgs.

private void ShowPropertiesOfSlateBlue(PaintEventArgs e)
{
    Color slateBlue = Color.FromName("SlateBlue");
    byte g = slateBlue.G;
    byte b = slateBlue.B;
    byte r = slateBlue.R;
    byte a = slateBlue.A;
    string text = String.Format("Slate Blue has these ARGB values: Alpha:{0}, " +
        "red:{1}, green: {2}, blue {3}", new object[]{a, r, g, b});
    e.Graphics.DrawString(text, 
        new Font(this.Font, FontStyle.Italic), 
        new SolidBrush(slateBlue), 
        new RectangleF(new PointF(0.0F, 0.0F), this.Size));
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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