CxImage实现9PNG

CxImage* ScaleImageBy9PNG(CxImage *pRawImage, int nDstWidth,int nDstHeight)
{
    if(NULL == pRawImage) return NULL;

    CDC *pDC = CDC::FromHandle(::GetDC(NULL));
    CDC memDC;
    memDC.CreateCompatibleDC(pDC);

    const UINT nBMPWidth = nDstWidth;
    const UINT nBMPHeight= nDstHeight;
    const UINT nRawWidth = pRawImage->GetWidth();
    const UINT nRawHeight = pRawImage->GetHeight();

    BITMAPINFO bitmapinfo;
    bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bitmapinfo.bmiHeader.biBitCount = 32;
    bitmapinfo.bmiHeader.biHeight = nBMPHeight;
    bitmapinfo.bmiHeader.biWidth = nBMPWidth;
    bitmapinfo.bmiHeader.biPlanes = 1;
    bitmapinfo.bmiHeader.biCompression=BI_RGB;
    bitmapinfo.bmiHeader.biXPelsPerMeter=0;
    bitmapinfo.bmiHeader.biYPelsPerMeter=0;
    bitmapinfo.bmiHeader.biClrUsed=0;
    bitmapinfo.bmiHeader.biClrImportant=0;
    bitmapinfo.bmiHeader.biSizeImage = bitmapinfo.bmiHeader.biWidth * bitmapinfo.bmiHeader.biHeight * bitmapinfo.bmiHeader.biBitCount / 8;
    HBITMAP    hBitmap = ::CreateDIBSection (memDC.m_hDC,&bitmapinfo, 0,NULL, 0, 0);
    

    CxImage *newImage = new CxImage();
    newImage->CreateFromHBITMAP(hBitmap);
    if (hBitmap != NULL)
    {
        DeleteObject(hBitmap);
    }
    ::ReleaseDC(NULL, pDC->m_hDC);
    if(memDC.m_hDC)        ::DeleteDC(memDC.m_hDC);

    int newImageHeight = newImage->GetHeight();
    int newImageWidth = newImage->GetWidth();
    if(FALSE == newImage->AlphaIsValid())
    {
        newImage->AlphaCreate();
    }
    if(newImageHeight > nRawHeight && newImageWidth > nRawWidth)
    {
        for(int iH=0;iH<newImageHeight;++iH)
            for(int iW=0;iW<newImageWidth;++iW)
            {
                int rawH = iH,rawW = iW;
                if(rawH >= (newImageHeight-nRawHeight/2))
                {
                    rawH = rawH - (newImageHeight - nRawHeight);
                }
                if(rawW >= (newImageWidth-nRawWidth/2))
                {
                    rawW = rawW - (newImageWidth - nRawWidth);
                }

                if((iH < nRawHeight/2 || iH>=(newImageHeight-nRawHeight/2))&&
                    (iW < nRawWidth/2 || iW>= (newImageWidth-nRawWidth/2)))
                {
                    //4块源
                    RGBQUAD argb = pRawImage->GetPixelColor(rawW,rawH,true);
                    newImage->SetPixelColor(iW,iH,RGB(argb.rgbRed,argb.rgbGreen,argb.rgbBlue));
                    newImage->AlphaSet(iW,iH,argb.rgbReserved);
                }
                else
                {
                    if((iH < nRawHeight/2 || iH>=(newImageHeight-nRawHeight/2))&&iW-1>=0)
                    {
                        RGBQUAD argb = newImage->GetPixelColor(iW-1,iH,true);
                        newImage->SetPixelColor(iW,iH,RGB(argb.rgbRed,argb.rgbGreen,argb.rgbBlue));
                        newImage->AlphaSet(iW,iH,argb.rgbReserved);
                    }
                    else
                    {
                        if(iH - 1 >= 0)
                        {
                            RGBQUAD argb = newImage->GetPixelColor(iW,iH-1,true);
                            newImage->SetPixelColor(iW,iH,RGB(argb.rgbRed,argb.rgbGreen,argb.rgbBlue));
                            newImage->AlphaSet(iW,iH,argb.rgbReserved);
                        }
                    }
                }
            }
    }
    return newImage;
}

9PNG的意思就是绘制时按9块区域绘制，左上左下右上右下是源，其他是拉伸的部分。CxImage主要使用像素点的方式来进行拉伸，并且每个像素都有copy透明信息。