Re: Testing native image scaling

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

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On Thu, 28 Mar 2019 03:35:09 +0900,
Andy Moreton wrote:
> 
> [1  <text/plain (7bit)>]
> On Wed 27 Mar 2019, Eli Zaretskii wrote:
> 
> >> Date: Wed, 27 Mar 2019 11:35:26 +0900
> >> From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
> >> Cc: Alan Third <alan@idiocy.org>,
> >> 	emacs-devel@gnu.org
> >> 
> >>   (insert-sliced-image (create-image "splash.png" nil nil :scale 0.5) nil nil 3 5)
> >> 
> >> Actually, I suspect this does not work on W32 because the comparison
> >> with the original image size is made for s->slice.width (or height)
> >> rather than s->img->width (or height) as I just did for cairo code.
> >> Could you check it on W32?
> >
> > It seems to work, but maybe I don't know what and how to check.  Can
> > you show what I should expect to see with and without the :scale
> > attribute, in "emacs -Q"?
> >
> > Thanks.
> 
> I would expect a sliced image to be composed of a grid of tiled images
> instead of a single image, but to have the same visual appearance as the
> original image. The w32 code does not get this right.

Thanks for the screenshot.  That's what I suspected from the code in
w32term.c and the documentation of StretchBlt.  Below is the
screenshot on Xrender, and it should be the expected result.  The
cursor is at the last row and the last column of the sliced image.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp


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