[pango/empty-line-height-attr-fix: 1/4] Use harfbuzz metrics for cairo fonts

[Matthias Clasen <matthiasc src gnome org>]

commit 20ec670e124e4461075a2967faa29603d25106cc
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 19 15:12:56 2021 -0400

    Use harfbuzz metrics for cairo fonts
    
    Without this, we end up with differences in
    metrics of empty runs.
    
    Fixes: #421

 pango/pangocairo-font.c | 43 ++++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 21 deletions(-)
---
diff --git a/pango/pangocairo-font.c b/pango/pangocairo-font.c
index 69c375c3..15c5be4a 100644
--- a/pango/pangocairo-font.c
+++ b/pango/pangocairo-font.c
@@ -784,40 +784,41 @@ struct _PangoCairoFontGlyphExtentsCacheEntry
 static gboolean
 _pango_cairo_font_private_glyph_extents_cache_init (PangoCairoFontPrivate *cf_priv)
 {
-  cairo_scaled_font_t *scaled_font = _pango_cairo_font_private_get_scaled_font (cf_priv);
-  cairo_font_extents_t font_extents;
-
-  if (G_UNLIKELY (scaled_font == NULL || cairo_scaled_font_status (scaled_font) != CAIRO_STATUS_SUCCESS))
-    return FALSE;
-
-  cairo_scaled_font_extents (scaled_font, &font_extents);
+  PangoCairoFont *cfont = cf_priv->cfont;
+  PangoFontMetrics *metrics = _pango_cairo_font_get_metrics (PANGO_FONT (cfont), NULL);
 
   cf_priv->font_extents.x = 0;
   cf_priv->font_extents.width = 0;
-  cf_priv->font_extents.height = pango_units_from_double (font_extents.ascent + font_extents.descent);
+  cf_priv->font_extents.height = metrics->ascent + metrics->descent;
+
   switch (cf_priv->gravity)
     {
       default:
       case PANGO_GRAVITY_AUTO:
       case PANGO_GRAVITY_SOUTH:
-       cf_priv->font_extents.y = - pango_units_from_double (font_extents.ascent);
-       break;
+       cf_priv->font_extents.y = - metrics->ascent;
+       break;
       case PANGO_GRAVITY_NORTH:
-       cf_priv->font_extents.y = - pango_units_from_double (font_extents.descent);
-       break;
+       cf_priv->font_extents.y = - metrics->descent;
+       break;
       case PANGO_GRAVITY_EAST:
       case PANGO_GRAVITY_WEST:
-       {
-         int ascent = pango_units_from_double (font_extents.ascent + font_extents.descent) / 2;
-         if (cf_priv->is_hinted)
-           ascent = PANGO_UNITS_ROUND (ascent);
-         cf_priv->font_extents.y = - ascent;
-       }
+       {
+         int ascent = (metrics->ascent + metrics->descent) / 2;
+         if (cf_priv->is_hinted)
+           ascent = PANGO_UNITS_ROUND (ascent);
+         cf_priv->font_extents.y = - ascent;
+       }
     }
 
-  cf_priv->glyph_extents_cache = g_new0 (PangoCairoFontGlyphExtentsCacheEntry, GLYPH_CACHE_NUM_ENTRIES);
-  /* Make sure all cache entries are invalid initially */
-  cf_priv->glyph_extents_cache[0].glyph = 1; /* glyph 1 cannot happen in bucket 0 */
+  pango_font_metrics_unref (metrics);
+
+  if (!cf_priv->glyph_extents_cache)
+    {
+      cf_priv->glyph_extents_cache = g_new0 (PangoCairoFontGlyphExtentsCacheEntry, GLYPH_CACHE_NUM_ENTRIES);
+      /* Make sure all cache entries are invalid initially */
+      cf_priv->glyph_extents_cache[0].glyph = 1; /* glyph 1 cannot happen in bucket 0 */
+    }
 
   return TRUE;
 }