On Jan 20, 2017, at 3:04 PM, Philip Race <[email protected]> wrote:
>                     . Note: I couldn't create a suitable image with Delta 
> encoding in image buffer. Hence this small change could not be tested.
Have you looked at image test suites such as 
http://bmptestsuite.sourceforge.net/?

> That is worrying me since I don't follow these lines are part of that:-
> 1684                     // Move to the position (xoff, yoff). Since l-is used
> 1685                     // to index into the scanline buffer, the calculation
> 1686                     // must be limited by the size
> 1687                     l += xoff + yoff*width;
> 1688                     l %= width;
> 1687 was already there but 1688 and the comment are new and 1688 looks wrong 
> to me
> as it would seem to throw away the y it just added in ...

Indeed, if xoff is in the half-closed interval [0,width), then (xoff + 
yoff*width) % width == xoff.

Brian

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