break: Add pango_attr_break api

So far, we've been applying attribute-based
customization while doing per-item tailoring.
But this is suboptimal, since it means we don't
have a full view of the log attrs, and can't
do invariant fixes that cross item boundaries.

Therefore, add a separate pango_attr_break
api that applies attributes to to the whole
paragraph, and make PangoLayout use it.

3 files changed, 62 insertions, 9 deletions

diff --git a/pango/break.c b/pango/break.c
index 271c8db7..c55d5f22 100644
--- a/pango/break.c
+++ b/pango/break.c
@@ -1729,6 +1729,8 @@ tailor_break (const char    *text,
  * and can be %NULL.
  *
  * See [func@Pango.tailor_break] for language-specific breaks.
+ *
+ * See [func@Pango.attr_break] for attribute-based customization.
  */
 void
 pango_default_break (const char    *text,
@@ -1754,8 +1756,8 @@ pango_default_break (const char    *text,
  * For most purposes you may want to use
  * [func@Pango.get_log_attrs].
  *
- * Deprecated: 1.44: Use [func@Pango.default_break] and
- *   [func@Pango.tailor_break]
+ * Deprecated: 1.44: Use [func@Pango.default_break],
+ *   [func@Pango.tailor_break] and func@Pango.attr_break].
  */
 void
 pango_break (const char    *text,
@@ -1790,6 +1792,10 @@ pango_break (const char    *text,
  * If @offset is not -1, it is used to apply attributes
  * from @analysis that are relevant to line breaking.
  *
+ * Note that it is better to pass -1 for @offset and
+ * use [func@Pango.attr_break] to apply attributes to
+ * the whole paragraph.
+ *
  * Since: 1.44
  */
 void
@@ -1818,6 +1824,38 @@ pango_tailor_break (const char    *text,
 }
 
 /**
+ * pango_attr_break:
+ * @text: text to break. Must be valid UTF-8
+ * @length: length of text in bytes (may be -1 if @text is nul-terminated)
+ * @attr_list: `PangoAttrList` to apply
+ * @offset: Byte offset of @text from the beginning of the paragraph
+ * @attrs: (array length=attrs_len): array with one `PangoLogAttr`
+ *   per character in @text, plus one extra, to be filled in
+ * @attrs_len: length of @attrs array
+ *
+ * Apply customization from attributes to the breaks in @attrs.
+ *
+ * The line breaks are assumed to have been produced
+ * by [func@Pango.default_break] and [func@Pango.tailor_break].
+ *
+ * Since: 1.50
+ */
+void
+pango_attr_break (const char    *text,
+                  int            length,
+                  PangoAttrList *attr_list,
+                  int            offset,
+                  PangoLogAttr  *attrs,
+                  int            attrs_len)
+{
+  GSList *attributes;
+
+  attributes = pango_attr_list_get_attributes (attr_list);
+  break_attrs (text, length, attributes, offset, attrs, attrs_len);
+  g_slist_free_full (attributes, (GDestroyNotify)pango_attribute_destroy);
+}
+
+/**
  * pango_get_log_attrs:
  * @text: text to process. Must be valid UTF-8
  * @length: length in bytes of @text
diff --git a/pango/pango-break.h b/pango/pango-break.h
index f514d168..a8e6c5b9 100644
--- a/pango/pango-break.h
+++ b/pango/pango-break.h
@@ -123,6 +123,13 @@ void                    pango_tailor_break      (const char    *text,
                                                  PangoLogAttr  *attrs,
                                                  int            attrs_len);
 
+PANGO_AVAILABLE_IN_1_50
+void                    pango_attr_break        (const char    *text,
+                                                 int            length,
+                                                 PangoAttrList *attr_list,
+                                                 int            offset,
+                                                 PangoLogAttr  *attrs,
+                                                 int            attrs_len);
 
 G_END_DECLS
 
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index f78d7daf..b6e0c217 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -4214,12 +4214,13 @@ process_line (PangoLayout    *layout,
 }
 
 static void
-get_items_log_attrs (const char   *text,
-                     int           start,
-                     int           length,
-                     GList        *items,
-                     PangoLogAttr *log_attrs,
-                     int           log_attrs_len)
+get_items_log_attrs (const char    *text,
+                     int            start,
+                     int            length,
+                     GList         *items,
+                     PangoAttrList *attrs,
+                     PangoLogAttr  *log_attrs,
+                     int            log_attrs_len)
 {
   int offset = 0;
   GList *l;
@@ -4235,12 +4236,18 @@ get_items_log_attrs (const char   *text,
       pango_tailor_break (text + item->offset,
                           item->length,
                           &item->analysis,
-                          item->offset,
+                          -1,
                           log_attrs + offset,
                           item->num_chars + 1);
 
       offset += item->num_chars;
     }
+
+  if (attrs && items)
+    {
+      PangoItem *item = items->data;
+      pango_attr_break (text + start, length, attrs, item->offset, log_attrs, log_attrs_len);
+    }
 }
 
 static PangoAttrList *
@@ -4517,6 +4524,7 @@ pango_layout_check_lines (PangoLayout *layout)
                              start - layout->text,
                              delimiter_index + delim_len,
                              state.items,
+                             shape_attrs,
                              layout->log_attrs + start_offset,
                              layout->n_chars + 1 - start_offset);