master 03ac24f 2/3: Use real DPI when rendering SVGs (bug#45124)

[Alan Third]

branch: master
commit 03ac24f23971d8b5c85ec9383135eb7768226bb6
Author: Alan Third <alan@idiocy.org>
Commit: Alan Third <alan@idiocy.org>

    Use real DPI when rendering SVGs (bug#45124)
    
    * src/image.c (svg_css_length_to_pixels): Pass in a DPI value instead
    of using a hard coded value.
    (svg_load_image): Set the DPI on the rsvg_handle, and pass it to
    svg_css_length_to_pixels.
---
 src/image.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/image.c b/src/image.c
index 7012003..79b275c 100644
--- a/src/image.c
+++ b/src/image.c
@@ -9776,11 +9776,8 @@ svg_load (struct frame *f, struct image *img)
 
 #if LIBRSVG_CHECK_VERSION (2, 46, 0)
 static double
-svg_css_length_to_pixels (RsvgLength length)
+svg_css_length_to_pixels (RsvgLength length, double dpi)
 {
-  /* FIXME: 96 appears to be a pretty standard DPI but we should
-     probably use the real DPI if we can get it.  */
-  double dpi = 96;
   double value = length.length;
 
   switch (length.unit)
@@ -9854,6 +9851,9 @@ svg_load_image (struct frame *f, struct image *img, char 
*contents,
   rsvg_handle = rsvg_handle_new_from_stream_sync (input_stream, base_file,
                                                  RSVG_HANDLE_FLAGS_NONE,
                                                  NULL, &err);
+  rsvg_handle_set_dpi_x_y (rsvg_handle, FRAME_DISPLAY_INFO (f)->resx,
+                           FRAME_DISPLAY_INFO (f)->resy);
+
   if (base_file)
     g_object_unref (base_file);
   g_object_unref (input_stream);
@@ -9865,6 +9865,9 @@ svg_load_image (struct frame *f, struct image *img, char 
*contents,
   rsvg_handle = rsvg_handle_new ();
   eassume (rsvg_handle);
 
+  rsvg_handle_set_dpi_x_y (rsvg_handle, FRAME_DISPLAY_INFO (f)->resx,
+                           FRAME_DISPLAY_INFO (f)->resy);
+
   /* 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"
@@ -9889,6 +9892,7 @@ svg_load_image (struct frame *f, struct image *img, char 
*contents,
   /* Try the instrinsic dimensions first.  */
   gboolean has_width, has_height, has_viewbox;
   RsvgLength iwidth, iheight;
+  double dpi = FRAME_DISPLAY_INFO (f)->resx;
 
   rsvg_handle_get_intrinsic_dimensions (rsvg_handle,
                                         &has_width, &iwidth,
@@ -9898,19 +9902,19 @@ svg_load_image (struct frame *f, struct image *img, 
char *contents,
   if (has_width && has_height)
     {
       /* Success!  We can use these values directly.  */
-      viewbox_width = svg_css_length_to_pixels (iwidth);
-      viewbox_height = svg_css_length_to_pixels (iheight);
+      viewbox_width = svg_css_length_to_pixels (iwidth, dpi);
+      viewbox_height = svg_css_length_to_pixels (iheight, dpi);
     }
   else if (has_width && has_viewbox)
     {
-      viewbox_width = svg_css_length_to_pixels (iwidth);
-      viewbox_height = svg_css_length_to_pixels (iwidth)
+      viewbox_width = svg_css_length_to_pixels (iwidth, dpi);
+      viewbox_height = svg_css_length_to_pixels (iwidth, dpi)
         * viewbox.width / viewbox.height;
     }
   else if (has_height && has_viewbox)
     {
-      viewbox_height = svg_css_length_to_pixels (iheight);
-      viewbox_width = svg_css_length_to_pixels (iheight)
+      viewbox_height = svg_css_length_to_pixels (iheight, dpi);
+      viewbox_width = svg_css_length_to_pixels (iheight, dpi)
         * viewbox.height / viewbox.width;
     }
   else if (has_viewbox)
@@ -10019,6 +10023,10 @@ svg_load_image (struct frame *f, struct image *img, 
char *contents,
   rsvg_handle = rsvg_handle_new_from_stream_sync (input_stream, base_file,
                                                  RSVG_HANDLE_FLAGS_NONE,
                                                  NULL, &err);
+
+  rsvg_handle_set_dpi_x_y (rsvg_handle, FRAME_DISPLAY_INFO (f)->resx,
+                           FRAME_DISPLAY_INFO (f)->resy);
+
   if (base_file)
     g_object_unref (base_file);
   g_object_unref (input_stream);
@@ -10030,6 +10038,9 @@ svg_load_image (struct frame *f, struct image *img, 
char *contents,
   rsvg_handle = rsvg_handle_new ();
   eassume (rsvg_handle);
 
+  rsvg_handle_set_dpi_x_y (rsvg_handle, FRAME_DISPLAY_INFO (f)->resx,
+                           FRAME_DISPLAY_INFO (f)->resy);
+
   /* 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"