[pango/line-breaking-fixes2: 2/8] layout: Simplify things one more time

[Matthias Clasen <matthiasc src gnome org>]

commit f7e1c6338eba0d775c55d9f4ea7f1ef86b95adc8
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Nov 14 17:04:29 2021 -0500

    layout: Simplify things one more time
    
    The key insight here is that if we find a broken item
    does not fit, we are only interested in finding an
    *earlier* breakpoint - the later ones aren't going
    to produce a shorter run.
    
    So we can just keep track of the last char we want
    to allow breaking at.
    
    This fixes the case of finding the minimum width
    with wrap mode PANGO_WRAP_WORD.

 pango/pango-layout.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index dd43b46f..594bd6ea 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -3880,13 +3880,13 @@ process_item (PangoLayout     *layout,
     }
   else
     {
-      int num_chars = item->num_chars;
-      int break_num_chars = num_chars;
+      int num_chars;
+      int break_num_chars = item->num_chars;
       int break_width = width;
       int orig_width = width;
       int break_extra_width = 0;
       gboolean retrying_with_char_breaks = FALSE;
-      gboolean *break_disabled;
+      int last_break_char = item->num_chars;
 
       if (processing_new_item)
         {
@@ -3899,9 +3899,6 @@ process_item (PangoLayout     *layout,
           pango_glyph_item_get_logical_widths (&glyph_item, layout->text, state->log_widths);
         }
 
-      break_disabled = g_alloca (sizeof (gboolean) * (item->num_chars + 1));
-      memset (break_disabled, 0, sizeof (gboolean) * (item->num_chars + 1));
-
     retry_break:
 
       /* break_extra_width gets normally set from find_break_extra_width inside
@@ -3929,7 +3926,7 @@ process_item (PangoLayout     *layout,
       /* See how much of the item we can stuff in the line. */
       width = 0;
 
-      for (num_chars = 0; num_chars < item->num_chars; num_chars++)
+      for (num_chars = 0; num_chars < last_break_char; num_chars++)
         {
           extra_width = find_break_extra_width (layout, state, num_chars);
 
@@ -3937,8 +3934,7 @@ process_item (PangoLayout     *layout,
             break;
 
           /* If there are no previous runs we have to take care to grab at least one char. */
-          if (!break_disabled[num_chars] &&
-              can_break_at (layout, state->start_offset + num_chars, retrying_with_char_breaks) &&
+          if (can_break_at (layout, state->start_offset + num_chars, retrying_with_char_breaks) &&
               (num_chars > 0 || line->runs))
             {
               break_num_chars = num_chars;
@@ -3952,9 +3948,9 @@ process_item (PangoLayout     *layout,
       if (layout->wrap == PANGO_WRAP_WORD_CHAR && force_fit && break_width + break_extra_width > 
state->remaining_width && !retrying_with_char_breaks)
         {
           retrying_with_char_breaks = TRUE;
-          num_chars = item->num_chars;
+          last_break_char = item->num_chars;
+          break_num_chars = item->num_chars;
           width = orig_width;
-          break_num_chars = num_chars;
           break_width = width;
           goto retry_break;
         }
@@ -4003,7 +3999,7 @@ process_item (PangoLayout     *layout,
                 break_width -= state->log_widths[state->log_widths_offset + break_num_chars - 1];
 
               if (break_width > state->remaining_width &&
-                  !break_disabled[break_num_chars] &&
+                  break_num_chars < last_break_char &&
                   break_num_chars > 1)
                 {
                   /* Unsplit the item, disable the breakpoint, try again */
@@ -4012,11 +4008,8 @@ process_item (PangoLayout     *layout,
                   pango_item_free (new_item);
                   pango_item_unsplit (item, length, break_num_chars);
 
-                  break_disabled[break_num_chars] = TRUE;
-
-                  num_chars = item->num_chars;
+                  last_break_char = break_num_chars;
                   width = orig_width;
-                  break_num_chars = num_chars;
                   break_width = width;
 
                   goto retry_break;