Color::FromArgb Method (Int32, Color)
Assembly: System.Drawing (in System.Drawing.dll)
Parameters
- alpha
- Type: System::Int32
The alpha value for the new Color. Valid values are 0 through 255.
- baseColor
- Type: System.Drawing::Color
| Exception | Condition |
|---|---|
| ArgumentException | alpha is less than 0 or greater than 255. |
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 Color structures from the three color component values (red, green, blue). Three Color structures are created, one for each primary color.
Iterates through a range of alpha values, changing the alpha value of a color.
During each iteration, sets the color of a brush to the modified color and paints a rectangle to show the color.
Repeats steps 2 and 3 for each primary color.
The alpha value is never fully opaque and the rectangles overlap so you get color-combination effects.
void FromArgb3( PaintEventArgs^ e ) { Graphics^ g = e->Graphics; // Opaque colors (alpha value defaults to 255 -- max value). Color red = Color::FromArgb( 255, 0, 0 ); Color green = Color::FromArgb( 0, 255, 0 ); Color blue = Color::FromArgb( 0, 0, 255 ); // Solid brush initialized to red. SolidBrush^ myBrush = gcnew SolidBrush( red ); int alpha; // x coordinate of first red rectangle int x = 50; // y coordinate of first red rectangle int y = 50; // Fill rectangles with red, varying the alpha value from 25 to 250. for ( alpha = 25; alpha <= 250; alpha += 25 ) { myBrush->Color = Color::FromArgb( alpha, red ); g->FillRectangle( myBrush, x, y, 50, 100 ); g->FillRectangle( myBrush, x, y + 250, 50, 50 ); x += 50; } x = 50; // y coordinate of first green rectangle y += 50; // Fill rectangles with green, varying the alpha value from 25 to 250. for ( alpha = 25; alpha <= 250; alpha += 25 ) { myBrush->Color = Color::FromArgb( alpha, green ); g->FillRectangle( myBrush, x, y, 50, 150 ); x += 50; } x = 50; // y coordinate of first blue rectangle y += 100; // Fill rectangles with blue, varying the alpha value from 25 to 250. for ( alpha = 25; alpha <= 250; alpha += 25 ) { myBrush->Color = Color::FromArgb( alpha, blue ); g->FillRectangle( myBrush, x, y, 50, 150 ); x += 50; } }
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
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.