MFC CListctr displays thumbnails

      We know that you can make by CImageList listctr show pictures, but with the addition of image size and image size must be consistent CImageList created to appear. Recently met a demand, we need to put a lot of sizes of jpeg images to display thumbnails of the list box.

     First create CImageList specified size

1 void CListEx::setCreateImageList(int iWidth, int iheight)
2 {
3     m_iImageWidth = iWidth;
4     m_iImageHeight = iheight;
5     m_imageList.Create(m_iImageWidth, m_iImageHeight, ILC_COLOR32, 20, 1);
6     SetImageList(&m_imageList, LVSIL_SMALL);
7 }

      Using Gdi to scale, the path is the path of the picture, jpeg supports, no conversion format

void CListEx::AddImage(LPCSTR imagePath)
{
    WCHAR path[512] = { 0 };
    ::MultiByteToWideChar(CP_ACP, 0, (const char *)imagePath, strlen(imagePath), path, sizeof(path));

    Gdiplus::Bitmap bmp(path);

    int sourceWidth = m_iImageWidth;
    int sourceHeight = bmp.GetHeight();

    if (sourceHeight > m_iImageHeight)
    {
        sourceHeight = m_iImageHeight;
    }
    else
    {
        sourceHeight =bmp.GetHeight (); 
    } 
    
    // set the size of thumbnails 
    Gdiplus pThumbnail :: = * Bitmap (Bitmap Gdiplus :: * ) bmp.GetThumbnailImage (SourceWidth, sourceHeight, NULL, NULL); 
    HBITMAP hBMP; 

    pThumbnail -> GetHBITMAP ( Color :: GDIPlus (LIST_BKCOLOR), & hBMP); 
    the CBitmap * = the pImage the CBitmap :: FromHandle (hBMP); 
    
    m_imageList.Add (the pImage, the RGB ( 255 , 0 , 255 )); 
    
    // the following code, and if not, will memory leak 
    Delete pThumbnail; 
    pThumbnail = NULL; 
    The pImage -> the DeleteObject (); 
    The pImage ->DeleteTempMap();
}

Do not forget to initialize gdi, add initialization code in CXXXApp :: InitInstance () in

    //初始化Gdi+
    Gdiplus::GdiplusStartupInput gdiplusStartupInput;
    Gdiplus::GdiplusStartup(&m_gdiplusToken, &gdiplusStartupInput, NULL);    

In CXXXApp :: ExitInstance () in the code to add closed gdi

Gdiplus::GdiplusShutdown(m_gdiplusToken);

 Add the declaration m_gdiplusToken in the header file CXXXApp's

ULONG_PTR m_gdiplusToken;