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);
}
}
}
|