Re: Image transformations

[Eli Zaretskii]

> Date: Sat, 15 Jun 2019 12:00:49 +0100
> From: Alan Third <address@hidden>
> Cc: Eli Zaretskii <address@hidden>, Stefan Monnier <address@hidden>,
>       Emacs Development <address@hidden>
> 
> For example how would we handle cropping? With the code in Emacs at
> the moment I cheated: I just reset the origin, and set the width and
> height; the rest of the image is still there, we just don’t display
> it. If we allow arbitrary translations and rotations after the crop,
> however, then it’s reasonable for the user to expect the cropped area
> to translate and rotate, without reintroducing areas previously
> cropped out. I don’t know how to get round this without, perhaps,
> modifying the mask, which isn’t supported on NS at least, or drawing
> the image to a new surface at the moment of cropping. I want to avoid
> that if possible, but it may be the only solution.

Another possible solution is not to support cropping, except with
ImageMagick.  Would that really be much of a loss, given that Emacs
can display a slice of an image since Emacs 21?