Fetching CBitmap out of CImageList

Question

I inserted bitmaps in CImageList in one Function and needed to change some of the images later in another function. But I am unable to extract the CBitmap. The code goes something like this:

CBitmap GetIndividualBitmap(CImageList oImgList, int nBmpNo) {

IMAGEINFO imgInfo;
imagelist.GetImageInfo(index,imgInfo);
CBitmap bmp;
bmp.FromHandle(imgInfo.hbmImage);
return bmp;

}

However all I get is a black screen. Could anyone please point out where I am going wrong?

Answer 1

A Google search on "CImageList Get Bitmap" produced http://www.codeguru.com/forum/archive/index.php/t-257564.html and http://www.codeproject.com/KB/graphics/getimagefromlist.aspx both of which seems like precisely what you are looking for?

Answer 2

Ok there are a number of errors in your code

1)You are passing the Image list by object which means it will copy it across. Passing it by reference is a far better plan.
2) You are not passing a pointer to the IMAGEINFO struct into the GetImageInfo.
3) You misunderstand how "FromHandle" works. FromHandle is a static function that returns a pointer to a Bitmap. In your code you are calling the function and then ignoring the CBitmap* returned and returning a copy of your newly constructed object (ie it contains nothing) which results in your black screen.

Taking all those into account you should have code that looks like this:

CBitmap* GetIndividualBitmap(CImageList& oImgList, int nBmpNo) 
{
    IMAGEINFO imgInfo;
    oImgList.GetImageInfo( nBmpNo, &imgInfo );
    return CBitmap::FromHandle( imgInfo.hbmImage );
}