Win32 GDI 在内存中绘制彩色的位图

LRESULT OnPaint(HWND hWnd)
{
    

    PAINTSTRUCT ps;
    HDC hdc = ::BeginPaint(hWnd, &ps);

    //1.创建静态文本框控件DC
    HDC hPictureDc = GetDC(hPicture);

    //2.创建和窗口DC兼容的内存DC,    
    HDC hMenDc = CreateCompatibleDC(hdc);

//3.创建内存位图
//这要注意,如果创建和内存DC兼容的位图就只有黑白色,不会有彩色
//所以要创建实际对象DC.窗口DC或静态控件DC兼容的内存位图

    HGDIOBJ hBitmap = CreateCompatibleBitmap(hdc, 500, 400);

    //把位图选入内存DC中
    HGDIOBJ hOldBitmap = SelectObject(hMenDc, hBitmap);

    //给内存填充一个白色的背景色,如不填充背景色为黑色
    RECT rect = { 0,0,500,400 };
    FillRect(hMenDc, &rect,(HBRUSH) GetStockObject(WHITE_BRUSH));

    //绘制你要绘制的位图
    DrawBitmap(hMenDc, 500, 400);

    //把内存DC中的位图复制到静态控件上显示出来
    //我这是缩放复制,原样复制可以用BiBlt函数
    StretchBlt(hPictureDc, 0, 0, 300, 200, hMenDc, 0, 0, 500, 400, SRCCOPY);
    
    //释放GDI对象资源
    
    SelectObject(hMenDc, hOldBitmap);
    DeleteObject(hBitmap);
    DeleteDC(hMenDc);
    DeleteDC(hPictureDc);

    EndPaint(hWnd, &ps);
    return LRESULT();
}