// 创建临时位图
HBITMAP bmBack, bmObject, bmMem, bmSave;
// 单色位图
bmBack = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);
bmObject = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);
// 与设备兼容位图
bmMem = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);
bmSave = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);
// 将创建的临时位图选入临时DC中
HBITMAP OldbmBack, OldbmObject, OldbmMem, OldbmSave;
OldbmBack = (HBITMAP)SelectObject(hBack, bmBack);
OldbmObject = (HBITMAP)SelectObject(hObject, bmObject);
OldbmMem = (HBITMAP)SelectObject(hMem, bmMem);
OldbmSave = (HBITMAP)SelectObject(hSave, bmSave);
// 设置映射模式
SetMapMode(hTemp, GetMapMode(hdc));
// 先保留原始位图
BitBlt(hSave, 0, 0, ptSize.x, ptSize.y, hTemp, 0, 0, SRCCOPY);
// 将背景颜色设置为需透明的颜色
cColor = SetBkColor(hTemp, cTransparentColor);
// 创建目标屏蔽码
BitBlt(hObject, 0, 0, ptSize.x, ptSize.y, hTemp, 0, 0, SRCCOPY);
// 恢复源DC的原始背景色
SetBkColor(hTemp, cColor);