Merge branch 'fix-small-caps-line-height' into 'main'

Fix line height with emulated small caps

Closes #622

See merge request GNOME/pango!543

5 files changed, 103 insertions, 14 deletions

diff --git a/pango/itemize.c b/pango/itemize.c
index 6c07e4c2..6380c12f 100644
--- a/pango/itemize.c
+++ b/pango/itemize.c
@@ -1045,7 +1045,8 @@ collect_font_scale (PangoContext  *context,
                     GList        **stack,
                     PangoItem     *item,
                     PangoItem     *prev,
-                    double        *scale)
+                    double        *scale,
+                    gboolean      *is_small_caps)
 {
   gboolean retval = FALSE;
   GList *l;
@@ -1123,11 +1124,14 @@ collect_font_scale (PangoContext  *context,
      }
 
    *scale = 1.0;
+   *is_small_caps = TRUE;
 
    for (l = *stack; l; l = l->next)
      {
        ScaleItem *entry = l->data;
        *scale *= entry->scale;
+       if (((PangoAttrInt *)entry->attr)->value != PANGO_FONT_SCALE_SMALL_CAPS)
+         *is_small_caps = FALSE;
        retval = TRUE;
      }
 
@@ -1152,11 +1156,15 @@ collect_font_scale (PangoContext  *context,
 static void
 apply_scale_to_item (PangoContext *context,
                      PangoItem    *item,
-                     double        scale)
+                     double        scale,
+                     gboolean      is_small_caps)
 {
   PangoFontDescription *desc;
   double size;
 
+  if (is_small_caps)
+    pango_analysis_set_size_font (&item->analysis, item->analysis.font);
+
   desc = pango_font_describe (item->analysis.font);
   size = scale * pango_font_description_get_size (desc);
 
@@ -1182,9 +1190,10 @@ apply_font_scale (PangoContext *context,
     {
       PangoItem *item = l->data;
       double scale;
+      gboolean is_small_caps;
 
-      if (collect_font_scale (context, &stack, item, prev, &scale))
-        apply_scale_to_item (context, item, scale);
+      if (collect_font_scale (context, &stack, item, prev, &scale, &is_small_caps))
+        apply_scale_to_item (context, item, scale, is_small_caps);
 
       prev = item;
     }
diff --git a/pango/pango-item-private.h b/pango/pango-item-private.h
index 6e20953f..9d2fa805 100644
--- a/pango/pango-item-private.h
+++ b/pango/pango-item-private.h
@@ -38,6 +38,24 @@ G_BEGIN_DECLS
 
 #define PANGO_ANALYSIS_FLAG_HAS_CHAR_OFFSET (1 << 7)
 
+typedef struct _PangoAnalysisPrivate PangoAnalysisPrivate;
+
+struct _PangoAnalysisPrivate
+{
+  gpointer reserved;
+  PangoFont *size_font;
+  PangoFont *font;
+
+  guint8 level;
+  guint8 gravity;
+  guint8 flags;
+
+  guint8 script;
+  PangoLanguage *language;
+
+  GSList *extra_attrs;
+};
+
 typedef struct _PangoItemPrivate PangoItemPrivate;
 
 #if defined(__x86_64__) && !defined(__ILP32__)
@@ -74,6 +92,10 @@ void               pango_analysis_collect_features    (const PangoAnalysis
                                                        guint                       length,
                                                        guint                      *num_features);
 
+void               pango_analysis_set_size_font       (PangoAnalysis              *analysis,
+                                                       PangoFont                  *font);
+PangoFont *        pango_analysis_get_size_font       (const PangoAnalysis        *analysis);
+
 GList *            pango_itemize_with_font            (PangoContext               *context,
                                                        PangoDirection              base_dir,
                                                        const char                 *text,
diff --git a/pango/pango-item.c b/pango/pango-item.c
index 2b2664c5..c599241f 100644
--- a/pango/pango-item.c
+++ b/pango/pango-item.c
@@ -68,6 +68,9 @@ pango_item_copy (PangoItem *item)
     ((PangoItemPrivate *)result)->char_offset = ((PangoItemPrivate *)item)->char_offset;
 
   result->analysis = item->analysis;
+  if (result->analysis.lang_engine)
+    g_object_ref (result->analysis.lang_engine);
+
   if (result->analysis.font)
     g_object_ref (result->analysis.font);
 
@@ -102,6 +105,9 @@ pango_item_free (PangoItem *item)
       g_slist_free (item->analysis.extra_attrs);
     }
 
+  if (item->analysis.lang_engine)
+    g_object_unref (item->analysis.lang_engine);
+
   if (item->analysis.font)
     g_object_unref (item->analysis.font);
 
@@ -324,3 +330,44 @@ pango_analysis_collect_features (const PangoAnalysis *analysis,
         }
     }
 }
+
+/*< private >
+ * pango_analysis_set_size_font:
+ * @analysis: a `PangoAnalysis`
+ * @font: a `PangoFont`
+ *
+ * Sets the font to use for determining the line height.
+ *
+ * This is used when scaling fonts for emulated Small Caps,
+ * to preserve the original line height.
+ */
+void
+pango_analysis_set_size_font (PangoAnalysis *analysis,
+                              PangoFont     *font)
+{
+  PangoAnalysisPrivate *priv = (PangoAnalysisPrivate *)analysis;
+
+  if (priv->size_font)
+    g_object_unref (priv->size_font);
+  priv->size_font = font;
+  if (priv->size_font)
+    g_object_ref (priv->size_font);
+}
+
+/*< private >
+ * pango_analysis_get_size_font:
+ * @analysis: a `PangoAnalysis`
+ *
+ * Gets the font to use for determining line height.
+ *
+ * If this returns `NULL`, use analysis->font.
+ *
+ * Returns: (nullable) (transfer none): the font
+ */
+PangoFont *
+pango_analysis_get_size_font (const PangoAnalysis *analysis)
+{
+  PangoAnalysisPrivate *priv = (PangoAnalysisPrivate *)analysis;
+
+  return priv->size_font;
+}
diff --git a/pango/pango-item.h b/pango/pango-item.h
index 8122be19..f0eebc01 100644
--- a/pango/pango-item.h
+++ b/pango/pango-item.h
@@ -61,8 +61,8 @@ typedef struct _PangoItem PangoItem;
 
 /**
  * PangoAnalysis:
- * @shape_engine: unused
- * @lang_engine: unused
+ * @shape_engine: unused, reserved
+ * @lang_engine: unused, reserved
  * @font: the font for this segment.
  * @level: the bidirectional level for this segment.
  * @gravity: the glyph orientation for this segment (A `PangoGravity`).
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 3f11d5b0..24a1a88b 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -5518,10 +5518,7 @@ pango_layout_get_empty_extents_and_height_at_index (PangoLayout    *layout,
                       free_font_desc = TRUE;
                     }
 
-                  pango_attr_iterator_get_font (&iter,
-                                                font_desc,
-                                                NULL,
-                                                NULL);
+                  pango_attr_iterator_get_font (&iter, font_desc, NULL, NULL);
 
                   attr = pango_attr_iterator_get (&iter, PANGO_ATTR_LINE_HEIGHT);
                   if (attr)
@@ -5689,11 +5686,25 @@ pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
 
   if (height)
     {
-      if (!metrics)
-        metrics = pango_font_get_metrics (run->item->analysis.font,
-                                          run->item->analysis.language);
+      if (pango_analysis_get_size_font (&run->item->analysis))
+        {
+          PangoFontMetrics *height_metrics;
+
+          height_metrics = pango_font_get_metrics (pango_analysis_get_size_font (&run->item->analysis),
+                                                   run->item->analysis.language);
+
+          *height = pango_font_metrics_get_height (height_metrics);
 
-      *height = pango_font_metrics_get_height (metrics);
+          pango_font_metrics_unref (height_metrics);
+        }
+      else
+        {
+          if (!metrics)
+            metrics = pango_font_get_metrics (run->item->analysis.font,
+                                              run->item->analysis.language);
+
+          *height = pango_font_metrics_get_height (metrics);
+        }
     }
 
   y_offset = run->y_offset;