[pango/ignore-width-in-horizontal] itemize: Ignore width in horizontal context

[Matthias Clasen <matthiasc src gnome org>]

commit 828b049e2d00b5da83a36ecfc92832a7cf99e220
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Aug 2 01:47:07 2021 -0400

    itemize: Ignore width in horizontal context
    
    Changes in width only need to break runs in
    vertical context. Implementing this requires
    some reorganization, since we need to compute
    the resolved gravity for the next run before
    determining the end of the run.
    
    Fixes: #503

 pango/pango-context.c | 76 ++++++++++++++++++++++++++++-----------------------
 1 file changed, 42 insertions(+), 34 deletions(-)
---
diff --git a/pango/pango-context.c b/pango/pango-context.c
index 4f15dd61..67505d9d 100644
--- a/pango/pango-context.c
+++ b/pango/pango-context.c
@@ -872,8 +872,11 @@ update_end (ItemizeState *state)
     state->run_end = state->attr_end;
   if (state->script_end < state->run_end)
     state->run_end = state->script_end;
-  if (state->width_iter.end < state->run_end)
-    state->run_end = state->width_iter.end;
+  if (PANGO_GRAVITY_IS_VERTICAL (state->resolved_gravity))
+    {
+      if (state->width_iter.end < state->run_end)
+        state->run_end = state->width_iter.end;
+    }
   if (state->emoji_iter.end < state->run_end)
     state->run_end = state->emoji_iter.end;
 }
@@ -1000,6 +1003,38 @@ width_iter_fini (PangoWidthIter* iter)
 {
 }
 
+static void
+itemize_state_update_resolved_gravity (ItemizeState *state)
+{
+  if (state->changed & (FONT_CHANGED | SCRIPT_CHANGED | WIDTH_CHANGED))
+    {
+      /* Font-desc gravity overrides everything */
+      if (state->font_desc_gravity != PANGO_GRAVITY_AUTO)
+        {
+          state->resolved_gravity = state->font_desc_gravity;
+        }
+      else
+        {
+          PangoGravity gravity = state->gravity;
+          PangoGravityHint gravity_hint = state->gravity_hint;
+
+          if (G_LIKELY (gravity == PANGO_GRAVITY_AUTO))
+            gravity = state->context->resolved_gravity;
+
+          state->resolved_gravity = pango_gravity_get_for_script_and_width (state->script,
+                                                                            state->width_iter.upright,
+                                                                            gravity,
+                                                                            gravity_hint);
+        }
+
+      if (state->font_desc_gravity != state->resolved_gravity)
+        {
+          pango_font_description_set_gravity (state->font_desc, state->resolved_gravity);
+          state->changed |= FONT_CHANGED;
+        }
+    }
+}
+
 static void
 itemize_state_init (ItemizeState               *state,
                     PangoContext               *context,
@@ -1086,13 +1121,14 @@ itemize_state_init (ItemizeState               *state,
   if (state->emoji_iter.is_emoji)
     state->width_iter.end = MAX (state->width_iter.end, state->emoji_iter.end);
 
-  update_end (state);
-
   if (pango_font_description_get_set_fields (state->font_desc) & PANGO_FONT_MASK_GRAVITY)
     state->font_desc_gravity = pango_font_description_get_gravity (state->font_desc);
   else
     state->font_desc_gravity = PANGO_GRAVITY_AUTO;
 
+  itemize_state_update_resolved_gravity (state);
+  update_end (state);
+
   state->derived_lang = NULL;
   state->current_fonts = NULL;
   state->cache = NULL;
@@ -1143,6 +1179,8 @@ itemize_state_next (ItemizeState *state)
       state->changed |= WIDTH_CHANGED;
     }
 
+  /* Update resolved gravity before updating end */
+  itemize_state_update_resolved_gravity (state);
   update_end (state);
 
   return TRUE;
@@ -1404,36 +1442,6 @@ compute_derived_language (PangoLanguage *lang,
 static void
 itemize_state_update_for_new_run (ItemizeState *state)
 {
-  /* This block should be moved to update_attr_iterator, but I'm too lazy to
-   * do it right now */
-  if (state->changed & (FONT_CHANGED | SCRIPT_CHANGED | WIDTH_CHANGED))
-    {
-      /* Font-desc gravity overrides everything */
-      if (state->font_desc_gravity != PANGO_GRAVITY_AUTO)
-        {
-          state->resolved_gravity = state->font_desc_gravity;
-        }
-      else
-        {
-          PangoGravity gravity = state->gravity;
-          PangoGravityHint gravity_hint = state->gravity_hint;
-
-          if (G_LIKELY (gravity == PANGO_GRAVITY_AUTO))
-            gravity = state->context->resolved_gravity;
-
-          state->resolved_gravity = pango_gravity_get_for_script_and_width (state->script,
-                                                                            state->width_iter.upright,
-                                                                            gravity,
-                                                                            gravity_hint);
-        }
-
-      if (state->font_desc_gravity != state->resolved_gravity)
-        {
-          pango_font_description_set_gravity (state->font_desc, state->resolved_gravity);
-          state->changed |= FONT_CHANGED;
-        }
-    }
-
   if (state->changed & (SCRIPT_CHANGED | LANG_CHANGED))
     {
       PangoLanguage *old_derived_lang = state->derived_lang;