繪製透明圖片GDI和GDI+結合

hdc = BeginPaint(hWnd, &ps);
    RECT rt;
    GetClientRect(hWnd, &rt);
    HDC hdcClient = GetDC(hWnd);
    HDC hdcDraw = CreateCompatibleDC(hdcClient);
    
    HBITMAP hbmpNew = CreateCompatibleBitmap(hdcClient,rt.right - rt.left,rt.bottom - rt.top);
    SelectObject(hdcDraw,hbmpNew);
    
    HDC hdcSrc = CreateCompatibleDC(hdcClient);
    SelectObject(hdcSrc, g_hbmp);
    
    BitBlt(hdcDraw, 0, 0, rt.right - rt.left, rt.bottom - rt.top, hdcSrc, 0, 0, SRCCOPY);
    Graphics graphics(hdcDraw);

    HDC hdcDrawEllipse = CreateCompatibleDC(hdcClient);
    HBITMAP hbmpNewEllipse = CreateCompatibleBitmap(hdcClient,g_ix,g_iy);
    SelectObject(hdcDrawEllipse,hbmpNewEllipse);
    
    StretchBlt(hdcDrawEllipse, 0, 0, g_ix, g_iy, hdcSrc, g_iPointx-g_ix/4, g_iPointy-g_iy/4,g_ix/2,g_iy/2, SRCCOPY);

    HDC hdcDrawEllipseBack = CreateCompatibleDC(hdcClient);
    HBITMAP hbmpNewEllipseBack = CreateBitmap(g_ix, g_iy, 1, 1, 0);
    SelectObject(hdcDrawEllipseBack,hbmpNewEllipseBack);
    SolidBrush blackBrush(Color(255, 255, 255, 255));
    RectF ellipseRect(0, 0, g_ix, g_iy);
    Graphics graphicsEllipseBack(hdcDrawEllipseBack);
    graphicsEllipseBack.FillEllipse(&blackBrush, ellipseRect);
    
    SetTextColor( hdcDrawEllipse, RGB(0, 0, 0));// 圖片的前景部分被挖空成黑色
    SetBkColor(hdcDrawEllipse,RGB(255, 255, 255));// 圖片的背景部分留下

    BitBlt(hdcDrawEllipse, 0, 0, g_ix, g_iy, hdcDrawEllipseBack, 0,0, SRCAND);

    SetTextColor( hdcDraw, RGB(255, 255, 255));// 圖片的前景部分被挖空成黑色
    SetBkColor( hdcDraw, RGB(0, 0, 0));// 圖片的背景部分留下

    BitBlt(hdcDraw, g_iPointx-g_ix/2, g_iPointy-g_ix/2, g_ix, g_ix, hdcDrawEllipseBack, 0, 0, SRCAND);
    BitBlt(hdcDraw, g_iPointx-g_ix/2, g_iPointy-g_ix/2, g_ix, g_ix, hdcDrawEllipse, 0, 0, SRCPAINT);
    Example_RotateFlip(hdcDraw);
    BitBlt(hdcClient, 0, 0, rt.right - rt.left, rt.bottom - rt.top, hdcDraw, 0, 0, SRCCOPY);
    DeleteObject(hbmpNewEllipseBack);
    DeleteDC(hdcDrawEllipseBack);
    DeleteObject(hbmpNewEllipse);
    DeleteObject(hbmpNew);
    DeleteDC(hdcDrawEllipse);
    DeleteDC(hdcSrc);
    DeleteDC(hdcDraw);
    DeleteDC(hdcClient);

    EndPaint(hWnd, &ps);
    break;