Windows Messages and Pixel colors..

[__Cerb]

Is it possible to grab a certain pixel's color using WM messages? If so, which WM should I send and what kind of wParam and lParam would I need to send? Thanks, ~Mike

[Hesham Amin]

you can use GetPixel COLORREF GetPixel( HDC hdc, // handle to DC int nXPos, // x-coordinate of pixel int nYPos // y-coordinate of pixel ); why do you need SendMessage ?

[__Cerb]

Because I need to retrieve pixel colors from an inactive window.. Is it possible? Thanks ~Mike

[Hesham Amin]

__Cerb wrote: Is it possible? not sure... an inactive window isn't drawn!! .. needs to get the wm_paint to be redrawn..

[__Cerb]

What about ::GetDC(HWND hwnd) and ::ScreenToClient(HWND hwnd, LPPOINT lpPoint) ??? is there a way I could use those to get a pixel color?

[__Cerb]

Do I need to use ::GetDC, ::GetWindowDC, ::ScreenToClient, ::BitBlt, I really need to figure out how can I retrieve a pixel color from an inactive window. Thanks a lot, any help greatly appreciated ~Cerb

[Hesham Amin]

if you have the window handle then use GetWindowDC to get the HDC (device context) then use GetPixel directly... but the problem is when the window needs repaint.. in this case it amy give you another color,,, try this first and let us know the results :)

[__Cerb]

Damn, it still won't work. CString szWndName,szWndClass; szWndName = "My window"; szWndClass = "My window's class"; HWND hwnd = ::FindWindow(szWndName,szWndClass); ::PostMessage(hwnd,WM_PAINT,0,0); HDC hDC = ::GetWindowDC(hwnd); CString str; int iPixel; iPixel = ::GetPixel(hDC,50,75); str.Format("%d",iPixel); AfxMessageBox(str); It keeps returning -1, and it should return 263172 Any ideas?

[__Cerb]

Help please?

[Hesham Amin]

can you tell me what is the purpose of this operation ? maybe wecan find a way around it... why do you need to get the color of an in-active window ?