五、绘制图像

在视图类的OnDraw函数中绘制图像。当前源图像与客户区尺寸相同时，调用SetDIBitsToDevice绘制，这样可以加快绘制速度，否则调用StretchDIBits按比例缩放位图。

void CDIPView::OnDraw(CDC* pDC)

{

CDIPDoc* pDoc = GetDocument();

ASSERT_VALID(pDoc);

FIBITMAP *pFI = pDoc->m_pFI;

if(pFI){

BYTE* pBits = FreeImage_GetBits(pFI);

BITMAPINFO* pIf=FreeImage_GetInfo(pFI);

int W = FreeImage_GetWidth(pFI);

int H = FreeImage_GetHeight(pFI);

CRect rectClient;GetClientRect(rectClient);

int dstW = rectClient.Width();

int dstH = rectClient.Height();

::SetStretchBltMode(pDC->GetSafeHdc(),COLORONCOLOR);

if(dstW == W && dstH == H){

::SetDIBitsToDevice(pDC->GetSafeHdc(),0,0, W, H,0,0,0, H,pBits,pIf,DIB_RGB_COLORS);

}

else {//按比例缩放

float fScale=(float)(W*dstH)/(float)(H*dstW);

if(fScale > 1.0f)   

dstH = (int) (dstH / fScale);

else

    dstW = (int) (dstW * fScale);

::StretchDIBits(pDC->GetSafeHdc(),0,0,dstW,dstH,0,0,W,H,pBits,pIf,DIB_RGB_COLORS,SRCCOPY);

}

}

}