C++ Win32 API - CreateFont(): the documentation example is confusing

问题

The Win32 API function CreateFont() documentation has a confusing example:

As you can see below, they made 3 calls to CreateFont() using the same HANDLE (hFont).. and at the end they have called DeleteObject() for the last one only... but before EndPaint() (while the font is being select to the DC).

I've found this example so misleading about the way DeleteObject() must be used. I hope if someone could confirm or justify this code.

The example:

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    PAINTSTRUCT ps;
    HDC hdc;
    switch (message)
    {


    case WM_PAINT:
        {
        RECT rect;
        HBRUSH hBrush;
        HFONT hFont;
        hdc = BeginPaint(hWnd, &ps);


            //Logical units are device dependent pixels, so this will create a handle to a logical font that is 48 pixels in height.
            //The width, when set to 0, will cause the font mapper to choose the closest matching value.
            //The font face name will be Impact.
            hFont = CreateFont(48,0,0,0,FW_DONTCARE,FALSE,TRUE,FALSE,DEFAULT_CHARSET,OUT_OUTLINE_PRECIS,
                CLIP_DEFAULT_PRECIS,CLEARTYPE_QUALITY, VARIABLE_PITCH,TEXT("Impact"));
            SelectObject(hdc, hFont);

            //Sets the coordinates for the rectangle in which the text is to be formatted.
            SetRect(&rect, 100,100,700,200);
            SetTextColor(hdc, RGB(255,0,0));
            DrawText(hdc, TEXT("Drawing Text with Impact"), -1,&rect, DT_NOCLIP);


            //Logical units are device dependent pixels, so this will create a handle to a logical font that is 36 pixels in height.
            //The width, when set to 20, will cause the font mapper to choose a font which, in this case, is stretched.
            //The font face name will be Times New Roman.  This time nEscapement is at -300 tenths of a degree (-30 degrees)
            hFont = CreateFont(36,20,-300,0,FW_DONTCARE,FALSE,TRUE,FALSE,DEFAULT_CHARSET,OUT_OUTLINE_PRECIS,
                CLIP_DEFAULT_PRECIS,CLEARTYPE_QUALITY, VARIABLE_PITCH,TEXT("Times New Roman"));
            SelectObject(hdc,hFont);

            //Sets the coordinates for the rectangle in which the text is to be formatted.
            SetRect(&rect, 100, 200, 900, 800);
            SetTextColor(hdc, RGB(0,128,0));
            DrawText(hdc, TEXT("Drawing Text with Times New Roman"), -1,&rect, DT_NOCLIP);


            //Logical units are device dependent pixels, so this will create a handle to a logical font that is 36 pixels in height.
            //The width, when set to 10, will cause the font mapper to choose a font which, in this case, is compressed. 
            //The font face name will be Arial. This time nEscapement is at 250 tenths of a degree (25 degrees)
            hFont = CreateFont(36,10,250,0,FW_DONTCARE,FALSE,TRUE,FALSE,DEFAULT_CHARSET,OUT_OUTLINE_PRECIS,
                CLIP_DEFAULT_PRECIS,ANTIALIASED_QUALITY, VARIABLE_PITCH,TEXT("Arial"));
            SelectObject(hdc,hFont);

            //Sets the coordinates for the rectangle in which the text is to be formatted.
            SetRect(&rect, 500, 200, 1400, 600);
            SetTextColor(hdc, RGB(0,0,255));
            DrawText(hdc, TEXT("Drawing Text with Arial"), -1,&rect, DT_NOCLIP);
            DeleteObject(hFont);    

        EndPaint(hWnd, &ps);
        break;
        }
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

来源：https://stackoverflow.com/questions/61228227/c-win32-api-createfont-the-documentation-example-is-confusing

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