Re: Image transformations

[Alan Third <alan@idiocy.org>]

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On Sat, Jun 29, 2019 at 09:53:53PM +0200, Lars Ingebrigtsen wrote:
> Alan Third <alan@idiocy.org> writes:
> 
> > If you want to change to defaulting to ImageMagick where available I’m
> > sure we can.
> 
> I've resorted to using a function like this in every package that
> inserts an image:
> 
> (defun foo--image-type ()
>   (if (or (and (fboundp 'image-transforms-p)
> 	       (image-transforms-p))
> 	  (not (fboundp 'imagemagick-types)))
>       nil
>     'imagemagick))
> 
> Which is pretty annoying.

Something like the attached might help.

Although if someone included ImageMagick to support some obscure image
type it might result in slower image loads than native scaling for png
and jpeg, and so on.

I don’t know if we care much about that. Personally I’ve not noticed
any great speed increase, but anecdotally I’ve heard that native
transforms are far faster.

If it does turn out to be an issue then it should be quite easy to
just use ImageMagick to load the image, then use native transforms
when available.

-- 
Alan Third

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From dfc19db48f85538b0d60cd0b1e0787811f8daca2 Mon Sep 17 00:00:00 2001
From: Alan Third <alan@idiocy.org>
Date: Sun, 30 Jun 2019 15:24:46 +0100
Subject: [PATCH] Default to ImageMagick when transforms are requested

* lisp/image.el (create-image): Default to ImageMagick when transforms
are requested.
---
 lisp/image.el | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/lisp/image.el b/lisp/image.el
index b58b1dc954..70c988857c 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -436,13 +436,24 @@ create-image
 Image file names that are not absolute are searched for in the
 \"images\" sub-directory of `data-directory' and
 `x-bitmap-file-path' (in that order)."
+  (when (not (plist-get props :scale))
+    (let ((scale (image-compute-scaling-factor image-scaling-factor)))
+      (when (/= 1 scale) (setq props (append (list :scale scale) props)))))
+  ;; Default to ImageMagick if a transform is requested.
+  (if (and (not type)
+           (fboundp 'imagemagick-types)
+           (or (plist-get props :scale)
+               (plist-get props :width)
+               (plist-get props :height)
+               (plist-get props :max-width)
+               (plist-get props :max-height)
+               (plist-get props :rotation)
+               (plist-get props :crop)))
+      (setq type 'imagemagick))
   ;; It is x_find_image_file in image.c that sets the search path.
   (setq type (image-type file-or-data type data-p))
   (when (image-type-available-p type)
     (append (list 'image :type type (if data-p :data :file) file-or-data)
-            (and (not (plist-get props :scale))
-                 (list :scale
-                       (image-compute-scaling-factor image-scaling-factor)))
 	    props)))
 
 (defun image--set-property (image property value)
-- 
2.21.0