滚动后MSDN（所有者绘制）列表框控件冻结

Question

I'm working on an Owner-Drawn Listbox Control that i managed to create and populate without errors.

Here's my problem : When i scroll it, the listbox and its parent window becomes unresponsive after scrolling for a few seconds.(with PgDown)

Note that :

• There's a lot of items in it (more than 4k)

• The messages are still being processed, i can monitor them on the console and they are being sent and received. Only difference is, WM_DRAWITEM is no longer sent...

• The items of the listbox are added via LB_ADDSTRING

What i tried :

• Using the PeekMessage function instead of the GetMessage

-> Program crashes after the list is filled

• Redrawing the windows after the problem occurs (via a WM_LDOUBLECLICK event for example)

-> No effets

Code snippets :

• Window Procedure

   LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) { HBRUSH Brush; HBRUSH BLANK_BRUSH; HBRUSH BLUE_BRUSH; Brush = CreateSolidBrush(RGB(163, 255, 249)); BLANK_BRUSH = CreateSolidBrush(RGB(255,255, 255)); BLUE_BRUSH = CreateSolidBrush(RGB(0,0, 255)); int tabs[13]={140,256,261,287,318,353,422,460,500,530,550,570,610}; switch(msg) { HDC hdc ; PAINTSTRUCT ps ; PMEASUREITEMSTRUCT pmis; LPDRAWITEMSTRUCT Item; RECT rect ; rect.top=-50; rect.bottom=0; RECT rect2 ; rect.top=10; case WM_MEASUREITEM: pmis = (PMEASUREITEMSTRUCT) lParam; pmis->itemHeight = 17; return TRUE; break; case WM_DRAWITEM: Item = (LPDRAWITEMSTRUCT)lParam; if (Item->itemState & ODS_FOCUS) { SetTextColor(Item->hDC, RGB(255,255,255)); SetBkColor(Item->hDC, RGB(0, 0, 255)); FillRect(Item->hDC, &Item->rcItem, (HBRUSH)BLUE_BRUSH); } else { SetTextColor(Item->hDC, RGB(0,0,0)); SetBkColor(Item->hDC, RGB(255, 255, 255)); FillRect(Item->hDC, &Item->rcItem, (HBRUSH)BLANK_BRUSH); } int len = SendMessage(Item->hwndItem , LB_GETTEXTLEN, (WPARAM)Item->itemID, 0); if (len > 0) { LPCTSTR lpBuff = malloc((len+1)*sizeof(TCHAR)); len = SendMessage(Item->hwndItem , LB_GETTEXT, (WPARAM)Item->itemID, (LPARAM)lpBuff); if (len > 0) { TabbedTextOut(Item->hDC,Item->rcItem.left, Item->rcItem.top,(LPARAM)lpBuff,len,13,&tabs,140); } } return TRUE; break; case WM_CLOSE: DestroyWindow(hwnd); break; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; GetClientRect(hwnd, &rect); SetBkColor(hdc, RGB(230,50,2)); SetBkMode(hdc,TRANSPARENT); FillRect(hdc,&ps.rcPaint,Brush); DrawText(hdc, TEXT("Liste des messages décodés: "), -1, &rect, DT_CENTER ); DrawText(hdc, TEXT("Numéro d'engin (4xxxy): "), -1, &rect, DT_LEFT ); EndPaint (hwnd, &ps); return 0 ; case WM_DESTROY: PostQuitMessage(0); break; case WM_ERASEBKGND: return TRUE; break; default: return DefWindowProc(hwnd, msg, wParam, lParam); } return 0; } 

• Message Loop

    BOOL bRet;
           while (1)
            {
                bRet = GetMessage(&Msg, NULL, 0, 0);
                if (bRet > 0)
                {
                    TranslateMessage(&Msg);
                    DispatchMessage(&Msg);
                }
                else if (bRet == 0){
                    break;
                }
                else
                {
                    printf("error\n");
                    return -1;
                }
            }
            return Msg.wParam;

• Window creation

  WNDCLASSEX wc;

   wc.cbSize = sizeof(WNDCLASSEX); wc.style = 0; wc.lpfnWndProc = WndProc; wc.cbClsExtra = 0; wc.cbWndExtra = 0; wc.hInstance = hInstance; wc.hIcon = LoadIcon(NULL, IDI_APPLICATION); wc.hCursor = LoadCursor(NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); wc.lpszMenuName = NULL; wc.lpszClassName = g_szClassName; wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION); RegisterClassEx(&wc); hwnd = CreateWindowEx(WS_EX_CLIENTEDGE,g_szClassName,"List of messages",WS_OVERLAPPEDWINDOW,0, 0, 1500, 1000,NULL, NULL, hInstance, NULL); ShowWindow(hwnd, nCmdShow); UpdateWindow(hwnd); if(hwnd == NULL) { return 0; } hwnd2 = CreateWindowEx(0,"LISTBOX" ,"Data",WS_CHILD |WS_HSCROLL |WS_VSCROLL |WS_BORDER|WS_THICKFRAME | LBS_USETABSTOPS | LBS_OWNERDRAWFIXED | LBS_NOTIFY | LBS_HASSTRINGS,15,70,1450,450,hwnd,(HMENU) NULL,hInstance,NULL); 

It looks like there's a timer somewhere, and if a keyboard touch stays too long down, it somehow messes everything up...

Has someone encountered a problem like this before or could help me understand what is going on ?

Answer 1

You have a significant GDI resource leak in your code.

At the top of your WndProc function you're creating three brushes, and you never delete them. These brushes are created every time your window processes a message.

You should only create the brushes when you actually need them for painting, and call DeleteObject to release them when you're done with them.