平滑缩放位图，保存位图到bmp文件

   1: //Scale the SrcBitmap, with destWidth*destHeight

   2: void ScaleBitmap(CBitmap *pSrcBitmap, CBitmap *pDestBitmap, int destWidth, int destHeight)

   3: {

   4:     BITMAP bitmapInfo;

   5:     pSrcBitmap->GetBitmap(&bitmapInfo);

   6:     int srcWidth = bitmapInfo.bmWidth;

   7:     int srcHeight = bitmapInfo.bmHeight;

   8:  

   9:     HDC hScreenDC = ::GetDC(NULL);

  10:     CDC* pScreenDC = CDC::FromHandle(hScreenDC);

  11:     CDC* pSrcDC = new CDC();

  12:     pSrcDC->CreateCompatibleDC(pScreenDC);

  13:     CBitmap* pSrcOldBitmap = pSrcDC->SelectObject(pSrcBitmap);

  14:  

  15:     pDestBitmap->CreateCompatibleBitmap(pSrcDC,destWidth,destHeight);

  16:  

  17:     CDC* pDestDC = new CDC();

  18:     pDestDC->CreateCompatibleDC(pSrcDC);

  19:     CBitmap* pDestOldBitmap = pDestDC->SelectObject(pDestBitmap);

  20:  

  21:     pDestDC->SetStretchBltMode(HALFTONE);

  22:     pDestDC->StretchBlt(0,0,destWidth,destHeight,pSrcDC,0,0,srcWidth,srcHeight,SRCCOPY);

  23:     pDestDC->SelectObject(pDestOldBitmap);

  24:     pSrcDC->SelectObject(pSrcOldBitmap);

  25:  

  26:     delete pDestDC;

  27:     delete pSrcDC;

  28:  

  29:     ::ReleaseDC(NULL,hScreenDC);

  30: }

  31:  

  32: //Save a bitmap as a bitmap file

  33: //#include <atlimage.h>

  34: CBitmap* pSrcBitmap = new CBitmap();

  35: pSrcBitmap->Attach(hBitmap);

  36:  

  37: CBitmap* pDestBitmap = new CBitmap();

  38: ScaleBitmap(pSrcBitmap,pDestBitmap,destWidth,destHeight);

  39:  

  40: CImage image;

  41: image.Attach((HBITMAP)*pDestBitmap);

  42: image.Save(fileName, Gdiplus::ImageFormatBMP);

  43: image.Detach();

  44:  

  45: pSrcBitmap->Detach();

  46: delete pSrcBitmap;

  47: delete pDestBitmap;