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authorMatthias Clasen <mclasen@redhat.com>2021-11-11 19:58:21 -0500
committerMatthias Clasen <mclasen@redhat.com>2021-11-11 20:23:47 -0500
commit401237f4f19690771b5383a08dd71a638f77b2a0 (patch)
treeb39cd51dd5ac0892348f9c014587d5d7d45bf279
parent0c80c6d0b80cce4443e9a18fad2b4bccabaf4325 (diff)
downloadpango-401237f4f19690771b5383a08dd71a638f77b2a0.tar.gz
Try harder to not produce overlong linesavoid-overlong-lines
Our accounting for run lengths is imperfect (mainly due to log widths for clusters being evenly distributed), so it can happen that after reshaping the split item, we find that it does not actually fit in the remaining width. Previously, we would just use the split run at that point and produce an overlong line. Instead, undo the split, disable the breakpoint we used, and try again.
-rw-r--r--pango/pango-layout.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 7731532c..fad92b3b 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -3525,6 +3525,29 @@ shape_tab (PangoLayoutLine *line,
}
}
+#define DISABLE_BREAKPOINT_FLAG (1 << 16)
+
+static inline void
+disable_breakpoint (PangoLayout *layout,
+ int offset)
+{
+ layout->log_attrs[offset].reserved |= DISABLE_BREAKPOINT_FLAG;
+}
+
+static inline gboolean
+breakpoint_is_disabled (PangoLayout *layout,
+ int offset)
+{
+ return (layout->log_attrs[offset].reserved & DISABLE_BREAKPOINT_FLAG) != 0;
+}
+
+static void
+clear_breakpoint_flags (PangoLayout *layout)
+{
+ for (int i = 0; i < layout->n_chars + 1; i++)
+ layout->log_attrs[i].reserved = 0;
+}
+
static inline gboolean
can_break_at (PangoLayout *layout,
gint offset,
@@ -3542,6 +3565,8 @@ can_break_at (PangoLayout *layout,
if (offset == layout->n_chars)
return TRUE;
+ else if (breakpoint_is_disabled (layout, offset))
+ return FALSE;
else if (wrap == PANGO_WRAP_WORD)
return layout->log_attrs[offset].is_line_break;
else if (wrap == PANGO_WRAP_CHAR)
@@ -3990,7 +4015,28 @@ process_item (PangoLayout *layout,
/* Add the width back, to the line, reshape, subtract the new width */
state->remaining_width += break_width;
insert_run (line, state, new_item, FALSE);
+
break_width = pango_glyph_string_get_width (((PangoGlyphItem *)(line->runs->data))->glyphs);
+ if (break_width > state->remaining_width &&
+ !breakpoint_is_disabled (layout, break_num_chars) &&
+ break_num_chars > 1)
+ {
+ /* Unsplit the item, disable the breakpoint, try again */
+
+ uninsert_run (line);
+ pango_item_free (new_item);
+ pango_item_unsplit (item, length, break_num_chars);
+
+ disable_breakpoint (layout, break_num_chars);
+
+ num_chars = item->num_chars;
+ width = orig_width;
+ break_num_chars = num_chars;
+ break_width = width;
+
+ goto retry_break;
+ }
+
state->remaining_width -= break_width;
state->log_widths_offset += break_num_chars;
@@ -4598,6 +4644,8 @@ pango_layout_check_lines (PangoLayout *layout)
}
while (!done);
+ clear_breakpoint_flags (layout);
+
g_free (state.log_widths);
g_list_free_full (state.baseline_shifts, g_free);