mfc显示透明背景代码看不大懂

/*-----------------显示透明背景图片-------------------*/

void CHIT_MOUSE::TransparentBitmap(HDC hdc, HBITMAP hBitmap, short xStart, short yStart, short xadd, short yadd, COLORREF cTransparentColor)
{
BITMAP m_bm;
COLORREF cColor;

// 创建临时DC
HDC hMem, hBack, hObject, hTemp, hSave;
hBack = CreateCompatibleDC(hdc);
hObject = CreateCompatibleDC(hdc);
hMem = CreateCompatibleDC(hdc);
hSave = CreateCompatibleDC(hdc);

hTemp = CreateCompatibleDC(hdc);

// 选入位图
SelectObject(hTemp, hBitmap);

GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&m_bm);

POINT ptSize;//显示位图宽高

ptSize.x = m_bm.bmWidth; // 取得位图的宽度

ptSize.y = m_bm.bmHeight; // 取得位图的该度

DPtoLP(hTemp, &ptSize, 1); // 转换为逻辑点值

HBITMAP bmBack, bmObject, bmMem, bmSave;// 创建临时位图

// 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);

SetBkColor(hTemp, cColor);// 恢复源DC的原始背景色

// 创建反转的目标屏蔽码
BitBlt(hBack, 0, 0, ptSize.x, ptSize.y, hObject, 0, 0, NOTSRCCOPY);

// 拷贝主DC的背景到目标DC
BitBlt(hMem, 0, 0, ptSize.x, ptSize.y, hdc, xStart, yStart, SRCCOPY);

// 屏蔽位图的显示区
BitBlt(hMem, 0, 0, ptSize.x, ptSize.y, hObject, 0, 0, SRCAND);

// 屏蔽位图中的透明色
BitBlt(hTemp, 0, 0, ptSize.x, ptSize.y, hBack, 0, 0, SRCAND);

// 将位图与目标DC的背景左异或操作
BitBlt(hMem, 0, 0, ptSize.x, ptSize.y, hTemp, 0, 0, SRCPAINT);

// 拷贝目标到屏幕上
StretchBlt(hdc, xStart, yStart, ptSize.x+xadd, ptSize.y+yadd, hMem, 0, 0, ptSize.x, ptSize.y,SRCCOPY);

// 恢复原始位图
BitBlt(hTemp, 0, 0, ptSize.x, ptSize.y, hSave, 0, 0, SRCCOPY);

// 删除临时内存位图
DeleteObject(SelectObject(hBack, OldbmBack));
DeleteObject(SelectObject(hObject, OldbmObject));
DeleteObject(SelectObject(hMem, OldbmMem));
DeleteObject(SelectObject(hSave, OldbmSave));

// 删除临时内存DC
DeleteDC(hMem);
DeleteDC(hBack);
DeleteDC(hObject);
DeleteDC(hSave);
DeleteDC(hTemp);

}
这段代码的含义及用法

已经注释很详细了，实在看不懂算了
直接调用
TransparentBitmap(HDC hdc, HBITMAP hBitmap, short xStart, short yStart, short xadd, short yadd, COLORREF cTransparentColor)
第一个参数传你View的 DC
第二个参数，位图句柄
然后是x y的起始坐标和结束坐标，最后是透明色（一般用白色作为透明色，看你的背景）