Можно при помощи вызова неуправляемого кода (или PInvoke), путем создания изображения с контрола:
| Код |
enum TernaryRasterOperations : uint
{
/// <summary>dest = source</summary>
SRCCOPY = 0x00CC0020,
/// <summary>dest = source OR dest</summary>
SRCPAINT = 0x00EE0086,
/// <summary>dest = source AND dest</summary>
SRCAND = 0x008800C6,
/// <summary>dest = source XOR dest</summary>
SRCINVERT = 0x00660046,
/// <summary>dest = source AND (NOT dest)</summary>
SRCERASE = 0x00440328,
/// <summary>dest = (NOT source)</summary>
NOTSRCCOPY = 0x00330008,
/// <summary>dest = (NOT src) AND (NOT dest)</summary>
NOTSRCERASE = 0x001100A6,
/// <summary>dest = (source AND pattern)</summary>
MERGECOPY = 0x00C000CA,
/// <summary>dest = (NOT source) OR dest</summary>
MERGEPAINT = 0x00BB0226,
/// <summary>dest = pattern</summary>
PATCOPY = 0x00F00021,
/// <summary>dest = DPSnoo</summary>
PATPAINT = 0x00FB0A09,
/// <summary>dest = pattern XOR dest</summary>
PATINVERT = 0x005A0049,
/// <summary>dest = (NOT dest)</summary>
DSTINVERT = 0x00550009,
/// <summary>dest = BLACK</summary>
BLACKNESS = 0x00000042,
/// <summary>dest = WHITE</summary>
WHITENESS = 0x00FF0062,
/// <summary>
/// Capture window as seen on screen. This includes layered windows
/// such as WPF windows with AllowsTransparency="true"
/// </summary>
CAPTUREBLT = 0x40000000
}
[DllImport("gdi32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool BitBlt(IntPtr hdc, int nXDest, int nYDest, int nWidth,
int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);
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и потом в нужном месте получаем цвет:
| Код |
Graphics gr = button1.CreateGraphics();
Bitmap image = new Bitmap(button1.Width, button1.Height, gr);
Graphics imageGr = Graphics.FromImage(image);
IntPtr controlDc = gr.GetHdc();
IntPtr imageDc = imageGr.GetHdc();
BitBlt(imageDc, 0, 0, button1.ClientRectangle.Width,
button1.ClientRectangle.Height, controlDc, 0, 0, TernaryRasterOperations.SRCCOPY);
gr.ReleaseHdc(controlDc);
imageGr.ReleaseHdc(imageDc);
image.GetPixel(5, 5); // получаем цвет
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