WIN32 透明贴图

/*---------------------------------------
   BITBLT.C -- BitBlt Demonstration
               (c) Charles Petzold, 1998
  ---------------------------------------*/

#include <windows.h>
#pragma comment(lib,"Msimg32.lib")
#include "resource.h"
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
HBITMAP hBit;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName [] = TEXT ("BitBlt") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;

     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_INFORMATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
     
     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("This program requires Windows NT!"),
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("BitBlt Demo"), 
                          WS_OVERLAPPEDWINDOW, 
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;
                          
     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;

     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     static int  cxClient, cyClient, cxSource, cySource ;
     static HDC         hdcClient, hdcWindow ;
     int         x, y ;
     HDC dc;
     PAINTSTRUCT ps ;
     static RECT re;
     static HBITMAP hBitMap;
     HBITMAP hBitMapHandle;
     BITMAP bit;
     static int cx,cy;
     static HDC t_dc;
     static HBITMAP hBackGround =NULL;
     HDC hdcBackGround,hdcPic;
     BITMAP bitPic,bitBack;
     static BITMAP pic,back;
     switch (message)
     {
     case WM_CREATE:
          cxSource = GetSystemMetrics (SM_CXSIZEFRAME) +
                     GetSystemMetrics (SM_CXSIZE) ;

          cySource = GetSystemMetrics (SM_CYSIZEFRAME) + 
                     GetSystemMetrics (SM_CYCAPTION);
           hBit = LoadBitmap(GetModuleHandle(NULL),MAKEINTRESOURCE(IDB_BITMAP1));
           hBackGround = LoadBitmap(GetModuleHandle(NULL),MAKEINTRESOURCE(IDB_BITMAP2));
	    //   GetObject(hBit,sizeof(BITMAP),&bit);
          if(hBit == NULL || hBackGround ==NULL);
          {
              OutputDebugStringA("error");
          }
         GetObject(hBit,sizeof(BITMAP),&pic);
         GetObject(hBackGround,sizeof(BITMAP),&back);
          return 0 ;

     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          
          cyClient = HIWORD (lParam) ;
          cx = GetSystemMetrics(SM_CXFULLSCREEN);
          cy = GetSystemMetrics(SM_CYFULLSCREEN);
          re.right = LOWORD(lParam);
          re.bottom = HIWORD(lParam);
          return 0 ;

     case WM_PAINT:
        
         hdcClient = BeginPaint (hwnd, &ps) ;
         hdcBackGround =CreateCompatibleDC(hdcClient);
         hdcPic = CreateCompatibleDC(hdcClient);
         SelectObject(hdcPic,hBit);
         SelectObject(hdcBackGround,hBackGround);
        // BitBlt(hdcClient,0,0,re.right,re.bottom,hdcBackGround,0,0,SRCCOPY);

         //可以放缩图片

         StretchBlt(hdcClient,0,0,re.right,re.bottom,hdcBackGround,0,0,back.bmWidth,back.bmHeight,SRCCOPY);
         TransparentBlt(hdcClient,100,100,pic.bmWidth,pic.bmHeight,hdcPic,0,0,pic.bmWidth,pic.bmHeight,RGB(255,255,255));
//把要贴图的图片的透明颜色，这设置下就OK了。我这要透明的颜色是白色。

         DeleteDC(hdcBackGround);
         DeleteDC(hdcPic);
         EndPaint (hwnd, &ps) ;
         return 0 ;

     case WM_DESTROY:
          DeleteObject(hBit);
          DeleteObject(hBackGround);
          DeleteObject(&pic);
          DeleteObject(&back);
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}