For strongest red or/and green or/and blue or/and alpha, use ushort.MaxValue. For white color, set all R, G and B to ushort.MaxValue!

C# Signature:

[DllImport("gdi32.dll", EntryPoint = "GdiGradientFill", ExactSpelling = true)]
public static extern bool GradientFill(
    IntPtr hdc,           // handle to DC
    IntPtr pVertex,    // array of vertices
    uint dwNumVertex,     // number of vertices
    IntPtr pMesh,           // array of gradients
    uint dwNumMesh,       // size of gradient array
    GRADIENT_FILL dwMode);           // gradient fill mode

C# Signature:

[DllImport("gdi32.dll", EntryPoint = "GdiGradientFill", ExactSpelling = true)]
public static extern bool GradientFill(
    IntPtr hdc,           // handle to DC
    TRIVERTEX[] pVertex,    // array of vertices
    uint dwNumVertex,     // number of vertices
    GRADIENT_RECT[] pMesh,    // array of gradient rectangles, that each one keeps two indices in pVertex array, to determine its bounds
    uint dwNumMesh,       // number of gradient rectangles to draw
    GRADIENT_FILL dwMode);           // Use either GRADIENT_FILL.RECT_H or GRADIENT_FILL.RECT_V. Using the value GRADIENT_FILL.TRIANGLE is wrong in this overload!

C# Signature:

[DllImport("gdi32.dll", EntryPoint = "GdiGradientFill", ExactSpelling = true)]
public static extern bool GradientFill(
    IntPtr hdc,           // handle to DC
    TRIVERTEX[] pVertex,    // array of vertices
    uint dwNumVertex,     // number of vertices
    GRADIENT_TRIANGLE[] pMesh, // array of gradient triangles, that each one keeps three indices in pVertex array, to determine its bounds
    uint dwNumMesh,       // number of gradient triangles to draw
    GRADIENT_FILL dwMode);           // Use only GRADIENT_FILL.TRIANGLE. Both values GRADIENT_FILL.RECT_H and GRADIENT_FILL.RECT_V are wrong in this overload!

VB Signature:

Declare Function GradientFill Lib "gdi32.dll" (TODO) As TODO

User-Defined Types:

TRIVERTEX

GRADIENT_RECT

GRADIENT_TRIANGLE

GRADIENT_FILL

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

The GDI32.dll does not contain a GradientFill() function. The actual entry point is GdiGradientFill(). That's why the 'EntryPoint' attribute is present.

This method creates one entry each for rectangles and triangles. It's just a matter of convenience and error checking by the compiler.

Tips & Tricks:

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Sample Code:

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