Thread: BeginPaint() & EndPaint();

i'm a bit confused on this subject.. can anyone give me a quick explanation of this? so an idiot like myself can understand it....

in message WM_PAINT:

i always notice that all code is inside of BeginPaint() & EndPaint();

but if i remove these functions the program still seems to run the same..... are these necessary? and why are they always used?
i notice it stores something in a Paintstruct (i don't know what this is) but the paintstruct is never used again... what exactly is stored in the paintstruct?

thnx in advance...

oh ok.. guess i better start using it then.... thnx

PAINSTRUCT is defined as follows:

Code:

typedef struct tagPAINTSTRUCT
{
           HDC hdc;  //handle to device context
           BOOL fErase; //flag to indicate whether the backround was painted
           RECT rcPaint; //rectangle of invalid region
           BOOL fRestore;  /* reserved 
           BOOL fIncUpdate;           for windows
           BYTE rgbReserved[32];      internal use  */
}PAINTSTRUCT;

By calling BeginPaint(hdc, &ps) you:
1) Validate the client area
2) Windows returns a handle to the device context
3) Fill in the areas of PAINTSRUCT

Now if youd don't call BeginPaint on WM_PAINT and you don't validate the client area with ValidateRect windows will keep sending a WM_PAINT message and totally screw up your program flow. EndPaint will release the device context 'hdc' that you created with BeginPaint.

Ah much appreciated... i get it now thnx