Re: Testing native image scaling

[Andy Moreton <andrewjmoreton@gmail.com>]

On Thu 28 Mar 2019, Eli Zaretskii wrote:

>> Date: Thu, 28 Mar 2019 11:26:46 +0900
>> From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
>> 
>> > > 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.
>
> Thanks, I think I fixed this now.

Confirmed.

Should the <kp-subtract> and <kp-add> bindings for `image-decrease-size'
and `image-increase-size' be adjusted to handle sliced images ?

Also, in w32 builds of emacs-26 'M-X image-rotate' on a (non-sliced)
image logs a message: "image--get-imagemagick-and-warn: Cannot rescale
images without ImageMagick support", whereas on master it does nothing.
Is image rotation expected to work on Windows ?

    AndyM