4,图像中间扩张

其实就是分成两部分，再用sleep（）,类似于动画效果

void CMy1_showbitmapView::OnDraw(CDC* pDC)
{
CMy1_showbitmapDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if (!pDoc)
return;

// TODO: add draw code for native data here
//this->StretchBitMap(pDC);
//控制缩放比例
int m_scale = 1;
//CDib类指针对象
BYTE* pBitmapData = _cdib.GetData();
LPBITMAPINFO pBitmapInfo = _cdib.GetInfo();
int bitmapHeight = _cdib.GetHeight();
int bitmapWidth = _cdib.GetWidth();
int scaledWidth = (int)(bitmapWidth * m_scale);
int scaledHeight = (int)(bitmapHeight * m_scale);
bool bGetRGB = _cdib.GetRGB();
if (!bGetRGB)
{
	return;
}

CPalette* hPalette = CreateBitmapPalette(&_cdib);
//将已创建的调色板调用到设备上下文中
CPalette* hOldPalette = pDC->SelectPalette(hPalette, true);
//实现调色板
pDC->RealizePalette();

for (int i = 0; i <= bitmapWidth/2; i++)
{
	::StretchDIBits(pDC->GetSafeHdc(), bitmapWidth/2-i, bitmapHeight/2-i,
		i*2, i,
		bitmapWidth / 2 - i, bitmapHeight / 2 - i,
		i*2, i,
		pBitmapData, pBitmapInfo,
		DIB_RGB_COLORS,
		SRCCOPY);

	::StretchDIBits(pDC->GetSafeHdc(), bitmapWidth / 2 - i, bitmapHeight / 2 - i,
		i * 2, i*2,
		bitmapWidth / 2 - i, bitmapHeight / 2 - i,
		i * 2, i*2,
		pBitmapData, pBitmapInfo,
		DIB_RGB_COLORS,
		SRCCOPY);
	Sleep(300);
}
pDC->SelectPalette(hOldPalette, true);
::DeleteObject(hPalette);

}