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我正在用 Win32 制作一个简单的游戏。目前，我在主文件中全局声明了大部分绘图对象，这样我就不必删除它们或重新加载位图。所以基本上我所有的位图都加载到 WM_CREATE 中，然后什么都不需要删除 - 有人告诉我，我可以依靠系统在项目终止时清理我的资源。在 WM_PAINT（大约每秒调用 10 次）中，我有很多 BitBlt() 调用，以及相当多的 SelectObject() 调用。运行大约 10 - 15 分钟后，SelectObject(). 什么会导致 SelectObject() 失败，我是否错误地使用了 GDI 对象？

例子：

// Top of the file
HDC hdc;
HDC hdcmem;
HDC hbcmem;
HBITMAP colorsprites, blackwhitesprites, nums;
HBITMAP hdcold, hdcbmold, hdcbm;

// Some functions to get the window ready

// More variables used for drawing:
HBITMAP bg, side, mainCont, tmpbm, tmpold, bm_left, bm_right, sidebg, win_bm;
PAINTSTRUCT ps;
RECT rc;
HDC tmphdc;
HDC tmp;
HFONT font;
HBRUSH hbr;
HPEN pen;
BITMAP structBitmapHeader;
HGDIOBJ hBitmap;
HCURSOR crosshairs = LoadCursorW(hInst, IDC_CROSS);
HCURSOR normal = LoadCursorW(hInst, IDC_ARROW);
POINT cursor;
bool addPass = false, ignorePass;

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
        case WM_CREATE:
            hdc = GetDC(hWnd);
            hdcmem = CreateCompatibleDC(hdc);
            GetClientRect(hWnd, &rc);
            hdcbm = CreateCompatibleBitmap(hdc, rc.right, rc.bottom);
            hbcmem = CreateCompatibleDC(hdcmem);
            hdcbmold = (HBITMAP)SelectObject(hdcmem, hdcbm);

            // Load bitmaps
            bg                  = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_BACKGROUND));
            mainCont            = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_GAME_CONT));
            side                = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SIDEINFO));
            colorsprites        = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_COLOR_SPRITES));
            blackwhitesprites   = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_BLACKWHITE_SPRITES));
            sidebg              = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SIDEBG));
            nums                = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_NUMBERS));
            bm_left             = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_LEFT));
            bm_right            = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_RIGHT));
            win_bm              = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_VICTORY));
            if(bg == NULL || mainCont == NULL || side == NULL || colorsprites == NULL 
            || blackwhitesprites == NULL || sidebg == NULL || nums == NULL || bm_left == NULL 
            || bm_right == NULL)
                ThrowError("A bitmap failed to load.");

            break;

        case WM_PAINT:
            BeginPaint(hWnd, &ps);

            // SelectObject() and BitBlt() are called a lot in here

            EndPaint(hWnd, &ps);

            break;

        case WM_DESTROY:
            // System will clean up all GDI stuff - no need to delete anything
            PostQuitMessage(0);
            break;
    }
}
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2 回答 2

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确保在销毁 DC 时，已将原始位图选回其中。当您的位图仍处于选中状态时，您永远不应该破坏 DC。

于 2013-06-05T03:48:58.660 回答
2

通过在 BeginPaint 之后调用 SaveDC 并在 EndPaint 之前调用 RestoreDC 可以使生活变得更轻松。这会将 DC 恢复到其被释放之前的原始状态。

http://msdn.microsoft.com/en-us/library/windows/desktop/dd162945(v=vs.85).aspx

于 2013-06-05T16:04:58.143 回答