[pango] Restore scaling of CoreText fonts.

[John Ralls <jralls src gnome org>]

commit f661cdbf8cfbdb2ba7241d8dfa4a579c6dfe0a94
Author: John Ralls <jralls ceridwen us>
Date:   Sun Apr 29 16:03:08 2018 -0700

    Restore scaling of CoreText fonts.
    
    Fixes bug 787867.

 pango/pangocairo-coretextfont.c    |   17 ++++++++++++++++-
 pango/pangocairo-coretextfontmap.c |    2 +-
 pango/pangocoretext-fontmap.c      |   15 ++++++++++++---
 pango/pangocoretext-private.h      |    2 ++
 pango/pangocoretext.c              |    5 +----
 tests/test-layout.c                |   11 +----------
 6 files changed, 33 insertions(+), 19 deletions(-)
---
diff --git a/pango/pangocairo-coretextfont.c b/pango/pangocairo-coretextfont.c
index c07f1c7..9dc3344 100644
--- a/pango/pangocairo-coretextfont.c
+++ b/pango/pangocairo-coretextfont.c
@@ -36,6 +36,7 @@ struct _PangoCairoCoreTextFont
 {
   PangoCoreTextFont font;
   PangoCairoFontPrivate cf_priv;
+  int abs_size;
 };
 
 struct _PangoCairoCoreTextFontClass
@@ -162,6 +163,17 @@ pango_cairo_core_text_font_create_base_metrics_for_context (PangoCairoFont *font
   return metrics;
 }
 
+static PangoFontDescription *
+pango_cairo_core_text_font_describe_absolute (PangoFont *font)
+{
+  PangoCairoCoreTextFont *cafont = (PangoCairoCoreTextFont *)font;
+  PangoFontDescription *desc = pango_font_describe (font);
+  
+  pango_font_description_set_absolute_size (desc, cafont->abs_size);
+
+  return desc;
+}
+
 static void
 pango_cairo_core_text_font_finalize (GObject *object)
 {
@@ -179,9 +191,10 @@ pango_cairo_core_text_font_class_init (PangoCairoCoreTextFontClass *class)
   PangoFontClass *font_class = PANGO_FONT_CLASS (class);
 
   object_class->finalize = pango_cairo_core_text_font_finalize;
-
+  /* font_class->describe defined by parent class PangoCoreTextFont. */
   font_class->get_glyph_extents = pango_cairo_core_text_font_get_glyph_extents;
   font_class->get_metrics = _pango_cairo_font_get_metrics;
+  font_class->describe_absolute = pango_cairo_core_text_font_describe_absolute;
 }
 
 static void
@@ -219,6 +232,8 @@ _pango_cairo_core_text_font_new (PangoCairoCoreTextFontMap  *cafontmap,
   cafont = g_object_new (PANGO_TYPE_CAIRO_CORE_TEXT_FONT, NULL);
   cfont = PANGO_CORE_TEXT_FONT (cafont);
 
+  cafont->abs_size = pango_core_text_font_key_get_size (key);
+
   _pango_core_text_font_set_ctfont (cfont, font_ref);
 
   if (synthesize_italic)
diff --git a/pango/pangocairo-coretextfontmap.c b/pango/pangocairo-coretextfontmap.c
index ba5dcec..5054b7a 100644
--- a/pango/pangocairo-coretextfontmap.c
+++ b/pango/pangocairo-coretextfontmap.c
@@ -186,5 +186,5 @@ static void
 pango_cairo_core_text_font_map_init (PangoCairoCoreTextFontMap *cafontmap)
 {
   cafontmap->serial = 1;
-  cafontmap->dpi = 72.;
+  cafontmap->dpi = 96.;
 }
diff --git a/pango/pangocoretext-fontmap.c b/pango/pangocoretext-fontmap.c
index 4d10184..c5cacab 100644
--- a/pango/pangocoretext-fontmap.c
+++ b/pango/pangocoretext-fontmap.c
@@ -806,6 +806,7 @@ get_context_matrix (PangoContext *context,
 /*
  * Helper functions for PangoCoreTextFontsetKey
  */
+static const double ppi = 72.0; /* typographic points per inch */
 
 static double
 pango_core_text_font_map_get_resolution (PangoCoreTextFontMap *fontmap,
@@ -817,7 +818,7 @@ pango_core_text_font_map_get_resolution (PangoCoreTextFontMap *fontmap,
   /* FIXME: acquire DPI from CoreText using some deafault font */
   g_warning ("FIXME: returning default DPI");
 
-  return 72.0;
+  return ppi;
 }
 
 static int
@@ -826,8 +827,16 @@ get_scaled_size (PangoCoreTextFontMap       *fontmap,
                  const PangoFontDescription *desc)
 {
   double size = pango_font_description_get_size (desc);
-
-  return .5 + pango_matrix_get_font_scale_factor (pango_context_get_matrix (context)) * size;
+  PangoMatrix *matrix = pango_context_get_matrix (context);
+  double scale_factor = pango_matrix_get_font_scale_factor (matrix);
+  
+  if (!pango_font_description_get_size_is_absolute(desc))
+  {
+    double dpi = pango_core_text_font_map_get_resolution (fontmap, context);
+    size *= (dpi/ppi);
+  }
+
+  return .5 +  scale_factor * size;
 }
 
 
diff --git a/pango/pangocoretext-private.h b/pango/pangocoretext-private.h
index c6c642c..76eb1eb 100644
--- a/pango/pangocoretext-private.h
+++ b/pango/pangocoretext-private.h
@@ -99,6 +99,8 @@ void                  _pango_core_text_font_set_ctfont           (PangoCoreTextF
 PangoFontDescription *_pango_core_text_font_description_from_ct_font_descriptor (CTFontDescriptorRef desc);
 
 _PANGO_EXTERN
+int                   pango_core_text_font_key_get_size             (const PangoCoreTextFontKey *key);
+_PANGO_EXTERN
 int                   pango_core_text_font_key_get_size    (const PangoCoreTextFontKey *key);
 _PANGO_EXTERN
 double                pango_core_text_font_key_get_resolution       (const PangoCoreTextFontKey *key);
diff --git a/pango/pangocoretext.c b/pango/pangocoretext.c
index 8cba1aa..2aa1810 100644
--- a/pango/pangocoretext.c
+++ b/pango/pangocoretext.c
@@ -225,10 +225,7 @@ pango_core_text_font_class_init (PangoCoreTextFontClass *class)
   object_class->finalize = pango_core_text_font_finalize;
 
   font_class->describe = pango_core_text_font_describe;
-  /* In CoreText the device unit is points so describe_absoulute and
-   * describe are the same.
-   */
-  font_class->describe_absolute = pango_core_text_font_describe;
+  /* font_class->describe_absolute is left virtual for PangoCairoCoreTextFont. */
   font_class->get_coverage = pango_core_text_font_get_coverage;
   font_class->find_shaper = pango_core_text_font_find_shaper;
   font_class->get_font_map = pango_core_text_font_get_font_map;
diff --git a/tests/test-layout.c b/tests/test-layout.c
index 07ca690..4bce443 100644
--- a/tests/test-layout.c
+++ b/tests/test-layout.c
@@ -265,18 +265,9 @@ test_file (const gchar *filename, GString *string)
   parse_params (contents, &width, &ellipsize_at, &ellipsize, &wrap);
 
   layout = pango_layout_new (context);
-/* The layout tests are predicated on scaling fonts to 90 DPI, but
- * Apple's font APIs (CoreText and CoreGraphics) don't work that way
- * so we have to use a bigger font to get the results to agree with
- * the expected values.
- */
-#if defined (HAVE_CORE_TEXT) && defined (HAVE_CAIRO_QUARTZ)
-  desc = pango_font_description_from_string ("Cantarell 14.5");
-#else
   desc = pango_font_description_from_string ("Cantarell 11");
-#endif
   pango_layout_set_font_description (layout, desc);
-  pango_font_description_free (desc); 
+  pango_font_description_free (desc);
 
   pango_layout_set_markup (layout, markup, length);
   g_free (contents);