Re: [1/2] windowscodecs: Implement GetPreview and GetThumbnail in the TIFF decoder.

[Vincent Povirk]

According to MSDN, GetPreview isn't supported on any decoder except
WMPhoto, and if that's true it should probably be returning
WINCODEC_ERR_UNSUPPORTEDOPERATION.

And why bother with GetThumbnail if you're not going to do it
properly? At least check whether a thumbnail exists in the image
before returning something.

[1/2] windowscodecs: Implement GetPreview and GetThumbnail in the TIFF decoder.

[Dmitry Timoshkov]

Vincent Povirk  wrote:
> According to MSDN, GetPreview isn't supported on any decoder except
> WMPhoto, and if that's true it should probably be returning
> WINCODEC_ERR_UNSUPPORTEDOPERATION.
>
> And why bother with GetThumbnail if you're not going to do it
> properly? At least check whether a thumbnail exists in the image
> before returning something.

That was to make WICExplorer happy. After looking at its source I've found
that it doesn't always check return values of GetThumbnail and GetPreview,
but checks for returned interface pointer instead. I'll send a proper patch.

Thanks.