[游戏模版8] Win32 透明贴图

>_<:The same with previous introduction. In the InitInstance fanction make a little change:

>_<:Yes just add another picture "dra.bmp" and give the handle to dra.And then call function MyPaint(...)

 hdc=GetDC(hWnd);
 mdc=CreateCompatibleDC(hdc);

 bg=(HBITMAP)LoadImage(NULL,"bg.bmp",IMAGE_BITMAP,,,LR_LOADFROMFILE);
 dra=(HBITMAP)LoadImage(NULL,"dra.bmp",IMAGE_BITMAP,,,LR_LOADFROMFILE);
 //名、类型、大小、加载方式；

 MyPaint(hdc);
 ReleaseDC(hWnd,hdc);

>_<:As following here is the MyPaint(...) function:

>_<:In this function :

• firstly, move the picture "bg.bmp" to CompatibleDC mdc by its handle bg.
• Then copy mdc to hdc. Until now there is no any change.
• And then move dra to mdc,latter using twice BitBlt.

Here we can see:the seventh line, only use mdc's lower part do an operation SRCAND; the eighth line,use another part of mdc do an operation SRCPAINT. (Why through the two steps can achieve transparency? It involves some knowledge of image science, here will not introduce. )

>_<!However,one thing must be reminded:the picture of dra.bmp must use following style form:

 Yes,the part that you don't want to show must use the black background and this part will be done the operation late than another part.And another part  includes that you want to show must be black, you don't want to show must be white!

>_<:MyPaint(...)

 void MyPaint(HDC hdc)
 {
     SelectObject(mdc,bg);
     BitBlt(hdc,,,,,mdc,,,SRCCOPY);//在窗口位置、大小、原图剪切位

     SelectObject(mdc,dra);
     BitBlt(hdc,,,,,mdc,,,SRCAND);
     BitBlt(hdc,,,,,mdc,,,SRCPAINT);
 }