Paint Structure

stores info about the window location, size

to define, use:

PAINTSTRUCT ps;

where:

typedef struct tagPAINTSTRUCT

{ HDC hdc; // device context

BOOL fErase; // flags where app should redraw

RECT rcPaint; // clipping area

BOOL fRestore; // reserved

BOOL fIncUpdate; // reserved

BYTE rgbReserved[32]; // reserved

} PAINTSTRUCT;

BOOL fErase – if this field is true user is responsible to repaint background (unless you specified a non-NULL background paint brush ie: wndclass.hbrBackground = GetStockObject(BLACK_BRUSH);)

RECT rcPaint – invalid region struct (.left, .top, .right, .bottom)

only this area will be rendered

to draw in a larger area call:

InvalidateRect(HWND hWnd, // win handle to invalidate

CONST RECT *lpRect, //ptr to invalid area

BOOL bErase); //erase flag for BeginPaint()

if lpRect == NULL whole window will be invalid (can be drawn)

bErase – if you set to TRUE, next call to BeginPaint() redraws the background with current or default brush (destroying everything), else nothing is done to background.