Merge branch 'approximated-sizes' into 'main'

font-desc: Use local double values to store sizes

Closes #580

See merge request GNOME/pango!377

3 files changed, 25 insertions, 9 deletions

diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index fd0df205..26d08404 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -2382,10 +2382,16 @@ pango_attr_iterator_get_font (PangoAttrIterator     *iterator,
 
   if (have_scale)
     {
+      /* We need to use a local variable to ensure that the compiler won't
+       * implicitly cast it to integer while the result is kept in registers,
+       * leading to a wrong approximation in i386 (with 387 FPU)
+       */
+      volatile double size = scale * pango_font_description_get_size (desc);
+
       if (pango_font_description_get_size_is_absolute (desc))
-        pango_font_description_set_absolute_size (desc, scale * pango_font_description_get_size (desc));
+        pango_font_description_set_absolute_size (desc, size);
       else
-        pango_font_description_set_size (desc, scale * pango_font_description_get_size (desc));
+        pango_font_description_set_size (desc, size);
     }
 }
 
diff --git a/pango/pango-markup.c b/pango/pango-markup.c
index 38e908c5..2828eab3 100644
--- a/pango/pango-markup.c
+++ b/pango/pango-markup.c
@@ -294,12 +294,16 @@ markup_data_close_tag (MarkupData *md)
 
       if (ot->has_base_font_size)
 	{
-	  /* Create a font using the absolute point size
-	   * as the base size to be scaled from
-	   */
-	  a = pango_attr_size_new (scale_factor (ot->scale_level,
-						 1.0) *
-				   ot->base_font_size);
+          /* Create a font using the absolute point size as the base size
+           * to be scaled from.
+           * We need to use a local variable to ensure that the compiler won't
+           * implicitly cast it to integer while the result is kept in registers,
+           * leading to a wrong approximation in i386 (with 387 FPU)
+           */
+          volatile double size;
+
+          size = scale_factor (ot->scale_level, 1.0) * ot->base_font_size;
+          a = pango_attr_size_new (size);
 	}
       else
 	{
diff --git a/pango/pangofc-fontmap.c b/pango/pangofc-fontmap.c
index 62f2cd4b..9c008411 100644
--- a/pango/pangofc-fontmap.c
+++ b/pango/pangofc-fontmap.c
@@ -2789,6 +2789,7 @@ pango_fc_font_description_from_pattern (FcPattern *pattern, gboolean include_siz
     {
       FcMatrix *fc_matrix;
       double scale_factor = 1;
+      volatile double scaled_size;
 
       if (FcPatternGetMatrix (pattern, FC_MATRIX, 0, &fc_matrix) == FcResultMatch)
         {
@@ -2802,7 +2803,12 @@ pango_fc_font_description_from_pattern (FcPattern *pattern, gboolean include_siz
           scale_factor = pango_matrix_get_font_scale_factor (&mat);
         }
 
-      pango_font_description_set_size (desc, scale_factor * size * PANGO_SCALE);
+      /* We need to use a local variable to ensure that the compiler won't
+       * implicitly cast it to integer while the result is kept in registers,
+       * leading to a wrong approximation in i386 (with 387 FPU)
+       */
+      scaled_size = scale_factor * size * PANGO_SCALE;
+      pango_font_description_set_size (desc, scaled_size);
     }
 
   /* gravity is a bit different.  we don't want to set it if it was not set on