GetPixel遍历(0,0)至(bm.width,bm.height)
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COLORREF GetPixel(
HDC hdc,
int nXPos,
int nYPos
);
Parameters
hdc
[in] Handle to the device context.
nXPos
[in] Specifies the logical x-coordinate of the pixel to be examined.
nYPos
[in] Specifies the logical y-coordinate of the pixel to be examined.
Return Values
The RGB value of the pixel indicates success. CLR_INVALID indicates that the pixel is outside of the current clipping region.