Bug 307196 – Unhinted fonts are measured incorrectly and drawing

2006-04-29  Behdad Esfahbod  <behdad@gnome.org>

        Bug 307196 – Unhinted fonts are measured incorrectly and drawing
        problems occur as a result

        * pango/pangofc-font.c (get_face_metrics),
        (pango_fc_font_get_raw_extents):
        * pango/pangoxft-font.c (_pango_xft_font_new): Rollback previous
        change that forced metrics hinting always on.

        * pango/pangocairo-fcfont.c (_pango_cairo_fc_font_new): Set fcfont
        metrics hinting based on cairo font options.

4 files changed, 61 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index 8fb678d5..07e1821f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2006-04-29  Behdad Esfahbod  <behdad@gnome.org>
+
+	Bug 307196 – Unhinted fonts are measured incorrectly and drawing
+	problems occur as a result
+
+	* pango/pangofc-font.c (get_face_metrics),
+	(pango_fc_font_get_raw_extents):
+	* pango/pangoxft-font.c (_pango_xft_font_new): Rollback previous
+	change that forced metrics hinting always on.
+
+	* pango/pangocairo-fcfont.c (_pango_cairo_fc_font_new): Set fcfont
+	metrics hinting based on cairo font options.
+
 2006-04-28  Behdad Esfahbod  <behdad@gnome.org>
 
 	Bug 339749 – pango_language_from_string issues
diff --git a/pango/pangocairo-fcfont.c b/pango/pangocairo-fcfont.c
index af4647c1..43882c83 100644
--- a/pango/pangocairo-fcfont.c
+++ b/pango/pangocairo-fcfont.c
@@ -645,5 +645,10 @@ _pango_cairo_fc_font_new (PangoCairoFcFontMap        *cffontmap,
 
   cffont->options = cairo_font_options_copy (_pango_cairo_context_get_merged_font_options (context));
   
+  /* fcfont's is_hinted controls metric hinting
+   */
+  PANGO_FC_FONT(cffont)->is_hinted = 
+    (cairo_font_options_get_hint_metrics(cffont->options) != CAIRO_HINT_METRICS_OFF);
+
   return PANGO_FC_FONT (cffont);
 }
diff --git a/pango/pangofc-font.c b/pango/pangofc-font.c
index a3583234..e3585acf 100644
--- a/pango/pangofc-font.c
+++ b/pango/pangofc-font.c
@@ -306,11 +306,22 @@ get_face_metrics (PangoFcFont      *fcfont,
       FT_Vector_Transform (&vector, &ft_matrix);
       metrics->ascent = PANGO_UNITS_26_6 (vector.y);
     }
-  else
+  else if (fcfont->is_hinted ||
+	   (face->face_flags & FT_FACE_FLAG_SCALABLE) == 0)
     {
       metrics->descent = - PANGO_UNITS_26_6 (face->size->metrics.descender);
       metrics->ascent = PANGO_UNITS_26_6 (face->size->metrics.ascender);
     }
+  else
+    {
+      FT_Fixed ascender, descender;
+
+      descender = FT_MulFix (face->descender, face->size->metrics.y_scale);
+      metrics->descent = - PANGO_UNITS_26_6 (descender);
+
+      ascender = FT_MulFix (face->ascender, face->size->metrics.y_scale);
+      metrics->ascent = PANGO_UNITS_26_6 (ascender);
+    }
 
   /* Versions of FreeType < 2.1.8 get underline thickness wrong
    * for Postscript fonts (always zero), so we need a fallback
@@ -348,12 +359,16 @@ get_face_metrics (PangoFcFont      *fcfont,
       metrics->strikethrough_position = (PANGO_SCALE * face->size->metrics.y_ppem) / 4;
     }
 
-  /* Quantize the underline and strikethrough position to integer values.
+  /* If hinting is on for this font, quantize the underline and strikethrough position
+   * to integer values.
    */
-  pango_quantize_line_geometry (&metrics->underline_thickness,
-				&metrics->underline_position);
-  pango_quantize_line_geometry (&metrics->strikethrough_thickness,
-				&metrics->strikethrough_position);
+  if (fcfont->is_hinted)
+    {
+      pango_quantize_line_geometry (&metrics->underline_thickness,
+				    &metrics->underline_position);
+      pango_quantize_line_geometry (&metrics->strikethrough_thickness,
+				    &metrics->strikethrough_position);
+    }
   
   PANGO_FC_FONT_UNLOCK_FACE (fcfont);
 }
@@ -812,8 +827,22 @@ pango_fc_font_get_raw_extents (PangoFcFont    *fcfont,
 	{
 	  logical_rect->x = 0;
 	  logical_rect->width = PANGO_UNITS_26_6 (gm->horiAdvance);
-	  logical_rect->y = - PANGO_UNITS_26_6 (face->size->metrics.ascender);
-	  logical_rect->height = PANGO_UNITS_26_6 (face->size->metrics.ascender - face->size->metrics.descender);
+	  if (fcfont->is_hinted ||
+	      (face->face_flags & FT_FACE_FLAG_SCALABLE) == 0)
+	    {
+	      logical_rect->y = - PANGO_UNITS_26_6 (face->size->metrics.ascender);
+	      logical_rect->height = PANGO_UNITS_26_6 (face->size->metrics.ascender - face->size->metrics.descender);
+	    }
+	  else
+	    {
+	      FT_Fixed ascender, descender;
+	      
+	      ascender = FT_MulFix (face->ascender, face->size->metrics.y_scale);
+	      descender = FT_MulFix (face->descender, face->size->metrics.y_scale);
+	      
+	      logical_rect->y = - PANGO_UNITS_26_6 (ascender);
+	      logical_rect->height = PANGO_UNITS_26_6 (ascender - descender);
+	    }
 	}
     }
   else
diff --git a/pango/pangoxft-font.c b/pango/pangoxft-font.c
index d0ef5caa..fe3844fb 100644
--- a/pango/pangoxft-font.c
+++ b/pango/pangoxft-font.c
@@ -96,6 +96,12 @@ _pango_xft_font_new (PangoXftFontMap *xftfontmap,
 					"pattern", pattern,
 					NULL);
 
+  /* Hack to force hinting of vertical metrics; hinting off for
+   * a Xft font just means to not hint outlines, but we still
+   * want integer line spacing, underline positions, etc
+   */
+  PANGO_FC_FONT (xfont)->is_hinted = TRUE;
+  
   xfont->xft_font = NULL;
 
   return xfont;