WM_PAINT handlers repaint their entire window without looking at the invalid area to optimize it, so this answer doesn’t really explain anything. – Mark Ransom Mar 16 ’14 at 20:50 Whether a program uses the invalid area or not, it still doesn’t have any way to know when something has been uncovered by other programs and needs repainting.
The WM_PAINT / WM_NCPAINT Messages . A window is responsible to paint its own display. A window should paint its display in response to a WM_PAINT message . If the non-client region should be updated then the painting should occur in WM_NCPAINT. WM_PAINT and WM_NCPAINT messages are only, 3/21/2015 · case WM_PAINT: { if (inst->Paint==NULL) break PAINTSTRUCT ps BeginPaint(inst->hwnd, &ps) RECT f GetClientRect(inst->hwnd,&f) int width=f.right-f.left int height =f.bottom-f.top image imgForm(width,height) FillRect(imgForm,&f,CreateSolidBrush(inst->clrBackColor)) inst->Paint(inst->hwnd,imgForm)//it’s a lambda BitBlt(ps.hdc,0,0,ps.rcPaint.right-ps.rcPaint.left,ps.rcPaint.bottom.
The parent window or dialog box of an owner-drawn list box (its owner) receives WM_DRAWITEM messages when a portion of the list box needs to be painted. An owner-drawn list box can list information other than, or in addition to, text strings. The owner of an owner-drawn list box must process the WM_DRAWITEM message .
Because of the above, there are messages that you will receive in a Window Procedure that you won’t receive in a Dialog Procedure. There are a few major differences between a Window Procedure and a Dialog Procedure: A Dialog Procedure returns a BOOL, a Window Procedure returns a LRESULT. A Dialog Procedure doesn’t need to handle WM_PAINT or WM_DESTROY.
First of all, as you probably know, Windows is driven by messages . Windows sends messages to programs (to specific windows, actually) for many different reasons, perhaps to tell a window to perform certain tasks. For example, Windows might tell a window to repaint itself by sending a WM_PAINT message .
This site might (hopefully) explain it a little better than I can, http://www.flounder.com/messaging.htm As far as I can see, the difference is that WM_SETTEXT simply tells your parent this area (control) needs to be updated/redrawn, it does not signify that the screens pixels have become messed up (thereby requiring a OnPaint message to be sent).
7/6/2015 · This is because when you modify or alter in any way the window graphic area the system asks you to redraw the interested part (yes part you’ll understand later) by means of the WM_PAINT message . When an application receive this message it must repaint the area.
