I need specifically to load a JPG image that was saved as a blob. GDI+ makes it very easy to retrieve images from files but not from databases...
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2 Answers
Take a look at Image::Image(IStream *, BOOL). This takes a pointer to a COM object implementing the IStream interface. You can get one of these by allocating some global memory with GlobalAlloc and then calling CreateStreamOnHGlobal on the returned handle. It'll look something like this:
shared_ptr<Image> CreateImage(BYTE *blob, size_t blobSize)
{
HGLOBAL hMem = ::GlobalAlloc(GMEM_MOVEABLE,blobSize);
BYTE *pImage = (BYTE*)::GlobalLock(hMem);
for (size_t iBlob = 0; iBlob < blobSize; ++iBlob)
pImage[iBlob] = blob[iBlob];
::GlobalUnlock(hMem);
CComPtr<IStream> spStream;
HRESULT hr = ::CreateStreamOnHGlobal(hMem,TRUE,&spStream);
shared_ptr<Image> image = new Image(spStream);
return image;
}
But with error checking and such (omitted here to make things clearer)
1 Comment
Eclipse
That's what I get for not trying to compile it.
First fetch your blog into a byte array then use something like this:
public static Image CreateImage(byte[] pict)
{
System.Drawing.Image img = null;
using (System.IO.MemoryStream stream = new System.IO.MemoryStream(pict)) {
img = System.Drawing.Image.FromStream(stream);
}
return img;
}
2 Comments
djeidot
what's the equivalent of MemoryStream on C++?
Jason Kealey
I originally misread the title and thought you were looking for C#. It appears MemoryStream is available in C++ too: msdn.microsoft.com/en-us/library/…