Re: Loading svg from memory using custom filename for base_uri

[Evgeny Zajcev <lg.zevlg@gmail.com>]

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пт, 4 дек. 2020 г. в 01:11, Evgeny Zajcev <lg.zevlg@gmail.com>:

>
>
> чт, 3 дек. 2020 г. в 22:57, Alan Third <alan@idiocy.org>:
>
>> On Thu, Dec 03, 2020 at 08:50:15PM +0300, Evgeny Zajcev wrote:
>> >
>> > Here is updated patch, with support for `:base-uri` for :file image
>> spec as
>> > well
>>
>> It looks good to me. There are two things I think we need. One is to
>> add an entry for :base-uri to the svg_format array in image.c,
>
> done!
>
> and
>> some documentation, if you fancy writing it?
>>
>> Documentation better to write when `svg-embed` will support this feature.
>

I wrote a new function `svg-embed-base-uri-image' to do the job, and wrote
documentation for it.



-- 
lg

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From ac2f4fe1ec8b2d848d815322ba683f99c7db2e36 Mon Sep 17 00:00:00 2001
From: Zajcev Evgeny <zevlg@yandex.ru>
Date: Thu, 3 Dec 2020 18:37:18 +0300
Subject: [PATCH] Explicitly specify svg base_uri using `:base-uri' image
 property

* src/image.c (svg_load): Check `:base-uri' image property to
  explicitly set base_uri for images embedded into SVG

* lisp/svg.el (svg-embed-base-uri-image): New function to embed images
  located relative to images `:base-uri'
---
 doc/lispref/display.texi | 20 ++++++++++++++++++++
 etc/NEWS                 | 11 +++++++++++
 lisp/svg.el              | 13 +++++++++++++
 src/image.c              | 20 +++++++++++++-------
 4 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index f86baf5936..0038a5c58d 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -5898,6 +5898,26 @@ SVG Images
 @end lisp
 @end defun
 
+@defun svg-embed-base-uri-image svg relative-filename &rest args
+To @var{svg} add an embedded (raster) image placed at
+@var{relative-filename}.  @var{relative-filename} is searched inside
+@code{file-name-directory} of the @code{:base-uri} svg image property.
+This makes embedding large images work very fast.
+
+@lisp
+;; Embeding /tmp/subdir/rms.jpg and /tmp/another/rms.jpg
+(svg-embed-base-uri-image svg "subdir/rms.jpg"
+           :width "100px" :height "100px"
+           :x "50px" :y "75px")
+(svg-embed-base-uri-image svg "another/rms.jpg"
+           :width "100px" :height "100px"
+           :x "75px" :y "50px")
+(svg-image svg :scale 1.0
+           :base-uri "/tmp/dummy"
+           :width 175 :height 175)
+@end lisp
+@end defun
+
 @defun svg-clip-path svg &rest args
 Add a clipping path to @var{svg}.  If applied to a shape via the
 @var{:clip-path} property, parts of that shape which lie outside of
diff --git a/etc/NEWS b/etc/NEWS
index 2fb33e342e..392b81f03c 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -24,6 +24,17 @@ applies, and please also update docstrings as needed.
 \f
 * Installation Changes in Emacs 28.1
 
+** Can explicitly specify base_uri for svg images.
+':base-uri' image property can be used to explicitly specify base_uri
+for embedded images into svg. ':base-uri' is supported for both file
+and data svg images.
+
++++
+** 'svg-embed-base-uri-image' added to embed images
+'svg-embed-base-uri-image' can be used to embed images located
+relatively to 'file-name-directory' of the ':base-uri' svg image property.
+This works much faster then 'svg-embed'.
+
 ** Cairo graphics library is now used by default if found.
 '--with-cairo' is now the default, if the appropriate development files
 are found by 'configure'.  Note that building with Cairo means using
diff --git a/lisp/svg.el b/lisp/svg.el
index eeb945f53b..6896e0088b 100644
--- a/lisp/svg.el
+++ b/lisp/svg.el
@@ -184,6 +184,19 @@ svg-embed
     `((xlink:href . ,(svg--image-data image image-type datap))
       ,@(svg--arguments svg args)))))
 
+(defun svg-embed-base-uri-image (svg relative-filename &rest args)
+  "Insert image placed at RELATIVE-FILENAME into the SVG structure.
+RELATIVE-FILENAME will be searched in `file-name-directory' of the
+image's `:base-uri' property.  If `:base-uri' is not specified for the
+image, then embedding won't work. Embedding large images using this
+function is much faster, then `svg-embed'."
+  (svg--append
+   svg
+   (dom-node
+    'image
+    `((xlink:href . ,relative-filename)
+      ,@(svg--arguments svg args)))))
+
 (defun svg-text (svg text &rest args)
   "Add TEXT to SVG."
   (svg--append
diff --git a/src/image.c b/src/image.c
index 5eb4132295..89ebc60c6c 100644
--- a/src/image.c
+++ b/src/image.c
@@ -9472,6 +9472,7 @@ DEFUN ("imagemagick-types", Fimagemagick_types, Simagemagick_types, 0, 0, 0,
   {":type",		IMAGE_SYMBOL_VALUE,			1},
   {":data",		IMAGE_STRING_VALUE,			0},
   {":file",		IMAGE_STRING_VALUE,			0},
+  {":base-uri",		IMAGE_STRING_VALUE,			0},
   {":ascent",		IMAGE_ASCENT_VALUE,			0},
   {":margin",		IMAGE_NON_NEGATIVE_INTEGER_VALUE_OR_PAIR, 0},
   {":relief",		IMAGE_INTEGER_VALUE,			0},
@@ -9698,10 +9699,11 @@ init_svg_functions (void)
 svg_load (struct frame *f, struct image *img)
 {
   bool success_p = 0;
-  Lisp_Object file_name;
+  Lisp_Object file_name, base_uri;
 
   /* If IMG->spec specifies a file name, create a non-file spec from it.  */
   file_name = image_spec_value (img->spec, QCfile, NULL);
+  base_uri = image_spec_value (img->spec, QCbase_uri, NULL);
   if (STRINGP (file_name))
     {
       int fd;
@@ -9721,15 +9723,16 @@ svg_load (struct frame *f, struct image *img)
 	  return 0;
 	}
       /* If the file was slurped into memory properly, parse it.  */
-      success_p = svg_load_image (f, img, contents, size,
-				  SSDATA (ENCODE_FILE (file)));
+      if (!STRINGP (base_uri))
+        base_uri = ENCODE_FILE (file);
+      success_p = svg_load_image (f, img, contents, size, SSDATA (base_uri));
       xfree (contents);
     }
   /* Else it's not a file, it's a Lisp object.  Load the image from a
      Lisp object rather than a file.  */
   else
     {
-      Lisp_Object data, original_filename;
+      Lisp_Object data;
 
       data = image_spec_value (img->spec, QCdata, NULL);
       if (!STRINGP (data))
@@ -9737,10 +9740,10 @@ svg_load (struct frame *f, struct image *img)
 	  image_error ("Invalid image data `%s'", data);
 	  return 0;
 	}
-      original_filename = BVAR (current_buffer, filename);
+      if (!STRINGP (base_uri))
+        base_uri = BVAR (current_buffer, filename);
       success_p = svg_load_image (f, img, SSDATA (data), SBYTES (data),
-                                  (NILP (original_filename) ? NULL
-				   : SSDATA (original_filename)));
+                                  (NILP (base_uri) ? NULL : SSDATA (base_uri)));
     }
 
   return success_p;
@@ -9838,6 +9841,7 @@ svg_load_image (struct frame *f, struct image *img, char *contents,
   eassume (rsvg_handle);
 
   /* Set base_uri for properly handling referenced images (via 'href').
+     Can be explicitly specified using `:base_uri' image property.
      See rsvg bug 596114 - "image refs are relative to curdir, not .svg file"
      <https://gitlab.gnome.org/GNOME/librsvg/issues/33>. */
   if (filename)
@@ -10002,6 +10006,7 @@ svg_load_image (struct frame *f, struct image *img, char *contents,
   eassume (rsvg_handle);
 
   /* Set base_uri for properly handling referenced images (via 'href').
+     Can be explicitly specified using `:base_uri' image property.
      See rsvg bug 596114 - "image refs are relative to curdir, not .svg file"
      <https://gitlab.gnome.org/GNOME/librsvg/issues/33>. */
   if (filename)
@@ -10684,6 +10689,7 @@ syms_of_image (void)
 
 #if defined (HAVE_RSVG)
   DEFSYM (Qsvg, "svg");
+  DEFSYM (QCbase_uri, ":base-uri");
   add_image_type (Qsvg);
 #ifdef HAVE_NTGUI
   /* Other libraries used directly by svg code.  */
-- 
2.25.1