public static extern bool GradientFill(
IntPtr hdc,
TRIVERTEX[] pVertex,
uint dwNumVertex,
GRADIENT_RECT[] pMesh,
uint dwNumMesh,
uint dwMode);
public static bool GradientFill(
this Graphics gr,
Rectangle rc,
Color startColor, Color endColor,
FillDirection fillDir)
{
// Initialize the data to be used in the call to GradientFill.
TRIVERTEX[] tva = new TRIVERTEX[2];
tva[0] = new TRIVERTEX(rc.X, rc.Y, startColor);
tva[1] = new TRIVERTEX(rc.Right, rc.Bottom, endColor);
GRADIENT_RECT[] gra = new GRADIENT_RECT[] { new GRADIENT_RECT(0, 1) };
// Get the hDC from the Graphics object.
IntPtr hdc = gr.GetHdc();
// PInvoke to GradientFill.
bool b;
b = Win32Helper.GradientFill(
hdc,
tva,
(uint)tva.Length,
gra,
(uint)gra.Length,
(uint)fillDir);
System.Diagnostics.Debug.Assert(b, string.Format(
"GradientFill failed: {0}",
System.Runtime.InteropServices.Marshal.GetLastWin32Error()));
// Release the hDC from the Graphics object.
gr.ReleaseHdc(hdc);
return b;
}