下面的代码演示了使用GetDIBits直接读取位图数据。



本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/iamshuke/archive/2010/07/20/5749948.aspx

下面的代码演示了使用GetDIBits直接读取位图数据。

下面的代码演示了使用GetDIBits直接读取位图数据。

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include <math.h>   
void CDibtestDlg::OnOK()    
{  
   // TODO: Add extra validation here   
   HDC hDesktopDC = ::GetDC(NULL);   
   HDC hTmpDC = CreateCompatibleDC(hDesktopDC);   
   HBITMAP hBmp = CreateCompatibleBitmap(hDesktopDC, 351, 250);    //351x250, 示例数据   
   SelectObject(hTmpDC, hBmp);   
   BitBlt(hTmpDC, 0, 0, 351, 250, hDesktopDC, 0, 0, SRCCOPY);   
   DeleteObject(hTmpDC);   
 
   BITMAP bm;   
   PBITMAPINFO bmpInf;   
   if(GetObject(hBmp,sizeof(bm),&bm)==0)   
   {   
       ::ReleaseDC(NULL,hDesktopDC);   
       return ;   
   }   
 
   int nPaletteSize=0;   
   if(bm.bmBitsPixel<16)   
       nPaletteSize=(int)pow(2,bm.bmBitsPixel);   
 
   bmpInf=(PBITMAPINFO)LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER)+   
       sizeof(RGBQUAD)*nPaletteSize+(bm.bmWidth+7)/8*bm.bmHeight*bm.bmBitsPixel);   
 
   BYTE* buf=((BYTE*)bmpInf) +    
       sizeof(BITMAPINFOHEADER)+   
       sizeof(RGBQUAD)*nPaletteSize;   
 
   //-----------------------------------------------   
   bmpInf->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);   
   bmpInf->bmiHeader.biWidth = bm.bmWidth;   
   bmpInf->bmiHeader.biHeight = bm.bmHeight;   
   bmpInf->bmiHeader.biPlanes = bm.bmPlanes;   
   bmpInf->bmiHeader.biBitCount = bm.bmBitsPixel;   
   bmpInf->bmiHeader.biCompression = BI_RGB;   
   bmpInf->bmiHeader.biSizeImage = (bm.bmWidth+7)/8*bm.bmHeight*bm.bmBitsPixel;   
   //-----------------------------------------------   
 
   if(!::GetDIBits(hDesktopDC,hBmp,0,(UINT)bm.bmHeight,buf,bmpInf,DIB_RGB_COLORS))   
   {   
       ::ReleaseDC(NULL,hDesktopDC);   
       LocalFree(bmpInf);   
       return ;   
   }   
 
   ::ReleaseDC(NULL,hDesktopDC);   
 
   CString sMsg;   
   sMsg.Format("BitsPixel:%d,%d,height:%d",   
       bm.bmBitsPixel,bm.bmWidth,bm.bmHeight);   
   AfxMessageBox(sMsg);   
 
   CClientDC dc(this);   
 
   int nOffset;   
   BYTE r,g,b;   
   int nWidth = bm.bmWidth*bm.bmBitsPixel/8;   
   nWidth = ((nWidth+3)/4)*4; //4字节对齐   
      
   if(bmpInf->bmiHeader.biBitCount == 8)   
   {          
       for(int i=0; i<bm.bmHeight; i++)   
       {   
           for(int j=0; j<bm.bmWidth; j++)   
           {   
               RGBQUAD rgbQ;   
               rgbQ = bmpInf->bmiColors[buf[i*nWidth+j]];   
               dc.SetPixel(j,bm.bmHeight-i,RGB(rgbQ.rgbRed,rgbQ.rgbGreen,rgbQ.rgbBlue)); //测试显示   
           }   
       }   
   }   
   else if(bmpInf->bmiHeader.biBitCount == 16)   
   {   
       for(int i=0; i<bm.bmHeight; i++)   
       {   
           nOffset = i*nWidth;   
           for(int j=0; j<bm.bmWidth; j++)   
           {   
               b = buf[nOffset+j*2]&0x1F;   
               g = buf[nOffset+j*2]>>5;   
               g |= (buf[nOffset+j*2+1]&0x03)<<3;   
               r = (buf[nOffset+j*2+1]>>2)&0x1F;   
 
               r *= 8;   
               b *= 8;   
               g *= 8;   
                  
               dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示   
           }   
       }   
   }   
   else if(bmpInf->bmiHeader.biBitCount == 24)   
   {   
       for(int i=0; i<bm.bmHeight; i++)   
       {   
           nOffset = i*nWidth;   
           for(int j=0; j<bm.bmWidth; j++)   
            {   
                b = buf[nOffset+j*3];   
                g = buf[nOffset+j*3+1];   
                r = buf[nOffset+j*3+2];   
                   
                dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示   
            }   
        }   
    }   
    else if(bmpInf->bmiHeader.biBitCount == 32)   
    {   
        for(int i=0; i<bm.bmHeight; i++)   
        {   
            nOffset = i*nWidth;   
            for(int j=0; j<bm.bmWidth; j++)   
            {   
                b = buf[nOffset+j*4];   
                g = buf[nOffset+j*4+1];   
                r = buf[nOffset+j*4+2];   
                   
                dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示   
            }   
        }   
    }   
  
    DeleteObject(hBmp);   
    LocalFree(bmpInf);   
  
    //CDialog::OnOK();   
}