Problem with DllImport
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Iam trying to get the pixel of a area in a screen of my program (for collison detection) the API call (GetPixel) seems to work..and it returns a int that i use with Color.FromArgb(int) (i think thats it) anyways when i try to convert the int i get back the color but...it doesnt convert correctly.....the A(alpha) of the color is always 0. Is there something i need to do before i try to convert the int ? Here is the code i use.
[DllImport("Gdi32.dll")] private static extern int GetPixel(IntPtr Handler,int x,int y); [DllImport("user32.dll")] private static extern IntPtr GetDesktopWindow(); // [DllImport("user32.dll")] private static extern IntPtr GetWindowDC(int Pointer); [DllImport("user32.dll")] private static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hdc); //Use a method Called check pixel (overloads Int X, Int Y) int j = CheckPixel(100,100); int jm =Convert.ToInt32(j); Color c = Color.FromArgb(jm); MessageBox.Show(c.ToString()); //method CheckPixel private int CheckPixel(int x,int y) { IntPtr DC = GetWindowDC(GetDesktopWindow().ToInt32()); int jm = GetPixel(DC,x,y); // // ReleaseDC(GetDesktopWindow(),DC); // return jm; }Thanks for your time. Jesse M The Code Project Is Your Friend... -
Iam trying to get the pixel of a area in a screen of my program (for collison detection) the API call (GetPixel) seems to work..and it returns a int that i use with Color.FromArgb(int) (i think thats it) anyways when i try to convert the int i get back the color but...it doesnt convert correctly.....the A(alpha) of the color is always 0. Is there something i need to do before i try to convert the int ? Here is the code i use.
[DllImport("Gdi32.dll")] private static extern int GetPixel(IntPtr Handler,int x,int y); [DllImport("user32.dll")] private static extern IntPtr GetDesktopWindow(); // [DllImport("user32.dll")] private static extern IntPtr GetWindowDC(int Pointer); [DllImport("user32.dll")] private static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hdc); //Use a method Called check pixel (overloads Int X, Int Y) int j = CheckPixel(100,100); int jm =Convert.ToInt32(j); Color c = Color.FromArgb(jm); MessageBox.Show(c.ToString()); //method CheckPixel private int CheckPixel(int x,int y) { IntPtr DC = GetWindowDC(GetDesktopWindow().ToInt32()); int jm = GetPixel(DC,x,y); // // ReleaseDC(GetDesktopWindow(),DC); // return jm; }Thanks for your time. Jesse M The Code Project Is Your Friend...Quote from MSDN: "GetPixel: The GetPixel function retrieves the red, green, blue (RGB) color value of the pixel at the specified coordinates. " This seems to imply that the Alpha value is undefined when returned from
GetPixel. It seems as though the Alpha is always zero, but then the docs don't say that so you can't trust it. I haven't been able to locate how to get the alpha value though :( -Nathan --------------------------- Hmmm... what's a signature?