什么是正确的方式来使用GDI对象

我在Win32做一个简单的游戏。目前，我在主文件中声明了大部分的绘图对象，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在WM_CREATE中，然后没有任何东西需要被删除——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(每秒调用大约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，选择对象()。什么会导致SelectObject()失败，我是否错误地使用了GDI对象?

的例子:

// 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;
    }
}