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POWhy the following code is not working?
 

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  1. POWhy the following code is not working?
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    <p>I have Created a static control using following styles...</p> <pre><code>picBoxDisp = CreateWindow("STATIC", "image box", WS_VISIBLE |WS_CHILD | SS_BITMAP |WS_TABSTOP | WS_BORDER, 50, 50, 250, 300, hwnd , (HMENU)10000, NULL, NULL); SetWindowLongPtr(picBoxDisp,GWLP_WNDPROC,(LONG) dispWndProc); </code></pre> <p>from someplace in my program I have the following code..</p> <pre><code>SendMessage(picBoxDisp,STM_SETIMAGE, (WPARAM) IMAGE_BITMAP,(LPARAM) hBitmap); </code></pre> <p>now inside the dispWndProc I have the following code..</p> <pre><code>LRESULT CALLBACK dispWndProc(HWND hwnd,UINT msg, WPARAM wParam, LPARAM lParam) { static HDC hdc; static PAINTSTRUCT paintSt; static RECT aRect; switch(msg) { case WM_PAINT: { hdc = BeginPaint(hwnd,&amp;paintSt); GetClientRect(hwnd,&amp;aRect); // the code for painting EndPaint(hwnd,&amp;paintSt); } break; case STM_SETIMAGE: { //painting code; HBITMAP img = (HBITMAP)lParam; BITMAP bmp; GetObject(img,sizeof(bmp),&amp;bmp); HDC imgDC = GetDC((HWND)img); HDC memDC = CreateCompatibleDC(imgDC); SelectObject(memDC,img); if((img==NULL))// ||(imgDC==NULL)||(memDC==NULL)) { MessageBox(NULL,"img is NULL","Bad Programming!!! Error",MB_OK); } else { StretchBlt(hdc,0,0,aRect.right,aRect.bottom, memDC,0,0,bmp.bmWidth,bmp.bmHeight, SRCCOPY); } } break; default: return DefWindowProc(hwnd,msg,wParam,lParam); } return 0; } </code></pre> <p><strong>can anyone tell why the lParam doesnt typecast back to HBITMAP.... why img is NULL ?</strong></p> <p>thanks in advance,</p>
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    1. USBen Voigt
    1. USAmit
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    1. COWhy subclass a Static control instead of just creating your own class? Generally you don't subclass another control unless you want to use and customize some of its existing functionality. Doing the painting code in STM_SETIMAGE is odd; typically you'd just store away the bitmap handle and call InvalidateRect, and then do all painting in WM_PAINT. Also; in SetWindowLongPtr, cast to LONG_PTR, not LONG; casting to LONG may casue this code to fail when compiled for win64.
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      1. POWhy the following code is not working?
      1. USBrendanMcK
 

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