Thread: Clipboard data in MDI

ok i have this procedure that will get a bitmap from the clipboard and display it in this child MDI window but the image will not show up until i move the window off the screen or if i resize it, does anyone see any flaws in this code. I am using Visual C++ 6 and Windows API on a windows XP box.

PHP Code:

LRESULT CALLBACK ClipProc( HWND hWnd,UINT Msg,WPARAM wParam,LPARAM lParam )
{
    HDC hdc;
    HDC memhdc;
    PAINTSTRUCT ps;
    HWND hGetClip;
    RECT rect;
    BITMAP bm;
    static HBITMAP hBitmap ;
    HBITMAP hBitmapClip;
    switch(Msg)
    {
        case WM_CREATE:
        {        
            hGetClip = CreateWindowEx(0,"BUTTON","Get Image",WS_CHILD | WS_VISIBLE,
                0,0,100,20,hWnd,(HMENU)HBUTTGETCLIP,NULL, 0);
            break;
        }
        case WM_COMMAND:
        {
            switch(LOWORD(wParam))
            {
                case HBUTTGETCLIP:
                {                    
                    if (hBitmap)
                    {
                        DeleteObject (hBitmap) ;
                        hBitmap = NULL ;
                    }
                    OpenClipboard (copyhwnd);
                    hBitmapClip = (HBITMAP)GetClipboardData (CF_BITMAP) ;
                    
                    if (hBitmapClip)
                    {                    
                        hBitmap = CopyBitmap (hBitmapClip) ;
                    }

                    CloseClipboard () ;
                    break;
                }
                default:
                {
                    break;
                }
            }
            break;
        }
        case WM_PAINT:
        {            
            hdc = BeginPaint(hWnd,&ps);
            if (hBitmap)
            {
                GetClientRect (hWnd, &rect) ;

                memhdc = CreateCompatibleDC (hdc) ;
                SelectObject (memhdc, hBitmap) ;
                GetObject (hBitmap, sizeof (BITMAP), (PSTR) &bm);                    
                SetStretchBltMode (hdc, COLORONCOLOR) ;
                StretchBlt (hdc,    0, 0, rect.right, rect.bottom,
                    memhdc, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY) ;

                DeleteDC (memhdc) ;
            }
            EndPaint(copyhwnd,&ps);
            break;
        }
        default:
        {            
            break;
        }
    }

    return DefMDIChildProc(hWnd, Msg, wParam, lParam);
} 


I have tried this and it still has the same outcome. it will only show the clipboard data if i resize teh child window or if i move the window so that the body is not visible in the parent, like move it so you can only see the title bar that you are dragging it by and then bringing it back up.

ahh, ok. I was putting the wrong hwnd into the call. i had tried something before i posted and was using that hwnd instead. it works now, thanks.

Also

watch the uninitialised variables (ie hBitmap being tested for NULL)

and non static vars ie the edits hwnd will be lost.

The paints have a different hwnd used.

I recomend after

InvalidateRect(hwnd, NULL, TRUE);

you tell the app to bypass the OS msg que and draw your window immediately with UpdateWindow()