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Color.FromArgb Method (Int32, Int32, Int32, Int32)

Creates a Color structure from the four ARGB component (alpha, red, green, and blue) values. Although this method allows a 32-bit value to be passed for each component, the value of each component is limited to 8 bits.

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

public static Color FromArgb(
	int alpha,
	int red,
	int green,
	int blue
)

Parameters

alpha
Type: System.Int32
The alpha component. Valid values are 0 through 255.
red
Type: System.Int32
The red component. Valid values are 0 through 255.
green
Type: System.Int32
The green component. Valid values are 0 through 255.
blue
Type: System.Int32
The blue component. Valid values are 0 through 255.

Return Value

Type: System.Drawing.Color
The Color that this method creates.

ExceptionCondition
ArgumentException

alpha, red, green, or blue is less than 0 or greater than 255.

To create an opaque color, set alpha to 255. To create a semitransparent color, set alpha to any value from 1 through 254.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler. The code performs the following actions:

  • Creates three brushes, each a different color. Each Color structure that is used to create a brush is created from four component values (alpha, red, green, blue).

  • Uses an imaginary triangle to position three circles.

  • Paints three overlapping circles, each centered on one vertex of the triangle, using a different brush for each circle.


public void FromArgb1(PaintEventArgs e)
{
    Graphics     g = e.Graphics;

    // Transparent red, green, and blue brushes.
    SolidBrush trnsRedBrush = new SolidBrush(Color.FromArgb(120, 255, 0, 0));
    SolidBrush trnsGreenBrush = new SolidBrush(Color.FromArgb(120, 0, 255, 0));
    SolidBrush trnsBlueBrush = new SolidBrush(Color.FromArgb(120, 0, 0, 255));

    // Base and height of the triangle that is used to position the
    // circles. Each vertex of the triangle is at the center of one of the
    // 3 circles. The base is equal to the diameter of the circles.
    float   triBase = 100;
    float   triHeight = (float)Math.Sqrt(3*(triBase*triBase)/4);

    // Coordinates of first circle's bounding rectangle.
    float   x1 = 40;
    float   y1 = 40;

    // Fill 3 over-lapping circles. Each circle is a different color.
    g.FillEllipse(trnsRedBrush, x1, y1, 2*triHeight, 2*triHeight);
    g.FillEllipse(trnsGreenBrush, x1 + triBase/2, y1 + triHeight,
        2*triHeight, 2*triHeight);
    g.FillEllipse(trnsBlueBrush, x1 + triBase, y1, 2*triHeight, 2*triHeight);
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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