Merge branch 'avoid-overlong-lines' into 'main'

layout: Try harder to not produce overlong lines

See merge request GNOME/pango!501

5 files changed, 112 insertions, 9 deletions

diff --git a/pango/pango-break.h b/pango/pango-break.h
index 5d791e27..797fefd1 100644
--- a/pango/pango-break.h
+++ b/pango/pango-break.h
@@ -97,6 +97,8 @@ struct _PangoLogAttr
   guint is_word_boundary            : 1;
   guint break_inserts_hyphen        : 1;
   guint break_removes_preceding     : 1;
+
+  guint reserved                    : 17;
 };
 
 PANGO_DEPRECATED_IN_1_44
diff --git a/pango/pango-item-private.h b/pango/pango-item-private.h
index ef3e8ed0..d37fc3f8 100644
--- a/pango/pango-item-private.h
+++ b/pango/pango-item-private.h
@@ -88,6 +88,10 @@ GList *            pango_itemize_post_process_items   (PangoContext
                                                        PangoLogAttr               *log_attrs,
                                                        GList                      *items);
 
+void               pango_item_unsplit                 (PangoItem *orig,
+                                                       int        split_index,
+                                                       int        split_offset);
+
 
 G_END_DECLS
 
diff --git a/pango/pango-item.c b/pango/pango-item.c
index 4b02c277..2b2664c5 100644
--- a/pango/pango-item.c
+++ b/pango/pango-item.c
@@ -138,7 +138,7 @@ G_DEFINE_BOXED_TYPE (PangoItem, pango_item,
  * Return value: new item representing text before @split_index, which
  *   should be freed with [method@Pango.Item.free].
  */
-PangoItem*
+PangoItem *
 pango_item_split (PangoItem *orig,
                   int        split_index,
                   int        split_offset)
@@ -164,6 +164,31 @@ pango_item_split (PangoItem *orig,
   return new_item;
 }
 
+/*< private >
+ * pango_item_unsplit:
+ * @orig: the item to unsplit
+ * @split_index: value passed to pango_item_split()
+ * @split_offset: value passed to pango_item_split()
+ *
+ * Undoes the effect of a pango_item_split() call with
+ * the same arguments.
+ *
+ * You are expected to free the new item that was returned
+ * by pango_item_split() yourself.
+ */
+void
+pango_item_unsplit (PangoItem *orig,
+                    int        split_index,
+                    int        split_offset)
+{
+  orig->offset -= split_index;
+  orig->length += split_index;
+  orig->num_chars += split_offset;
+
+  if (orig->analysis.flags & PANGO_ANALYSIS_FLAG_HAS_CHAR_OFFSET)
+    ((PangoItemPrivate *)orig)->char_offset -= split_offset;
+}
+
 static int
 compare_attr (gconstpointer p1, gconstpointer p2)
 {
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 1a460d4c..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)
@@ -3943,9 +3968,9 @@ process_item (PangoLayout     *layout,
        * the cluster here.  But should be fine in practice. */
       if (break_num_chars > 0 && break_num_chars < item->num_chars &&
           layout->log_attrs[state->start_offset + break_num_chars - 1].is_white)
-      {
+        {
           break_width -= state->log_widths[state->log_widths_offset + break_num_chars - 1];
-      }
+        }
 
       if (layout->wrap == PANGO_WRAP_WORD_CHAR && force_fit && break_width + break_extra_width > state->remaining_width && !retrying_with_char_breaks)
         {
@@ -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);
 
diff --git a/utils/viewer-render.c b/utils/viewer-render.c
index 6f7e96c5..d4b3f0f4 100644
--- a/utils/viewer-render.c
+++ b/utils/viewer-render.c
@@ -35,6 +35,7 @@
 gboolean opt_display = TRUE;
 int opt_dpi = 96;
 gboolean opt_pixels = FALSE;
+gboolean opt_pango_units = FALSE;
 const char *opt_font = "";
 gboolean opt_header = FALSE;
 const char *opt_output = NULL;
@@ -119,20 +120,38 @@ make_layout(PangoContext *context,
   if (size > 0)
     pango_font_description_set_size (font_description, size * PANGO_SCALE);
 
-  if (opt_width > 0)
-    pango_layout_set_width (layout, (opt_width * opt_dpi * PANGO_SCALE + 36) / 72);
+  if (opt_width >= 0)
+    {
+      if (opt_pango_units)
+        pango_layout_set_width (layout, opt_width);
+      else
+        pango_layout_set_width (layout, (opt_width * opt_dpi * PANGO_SCALE + 36) / 72);
+    }
 
-  if (opt_height > 0)
-    pango_layout_set_height (layout, (opt_height * opt_dpi * PANGO_SCALE + 36) / 72);
+  if (opt_height >= 0)
+    {
+      if (opt_pango_units)
+        pango_layout_set_width (layout, opt_height);
+      else
+        pango_layout_set_height (layout, (opt_height * opt_dpi * PANGO_SCALE + 36) / 72);
+    }
   else
     pango_layout_set_height (layout, opt_height);
 
   if (opt_indent != 0)
-    pango_layout_set_indent (layout, (opt_indent * opt_dpi * PANGO_SCALE + 36) / 72);
+    {
+      if (opt_pango_units)
+        pango_layout_set_indent (layout, opt_indent);
+      else
+        pango_layout_set_indent (layout, (opt_indent * opt_dpi * PANGO_SCALE + 36) / 72);
+    }
 
   if (opt_spacing != 0)
     {
-      pango_layout_set_spacing (layout, (opt_spacing * opt_dpi * PANGO_SCALE + 36) / 72);
+      if (opt_pango_units)
+        pango_layout_set_spacing (layout, opt_spacing);
+      else
+        pango_layout_set_spacing (layout, (opt_spacing * opt_dpi * PANGO_SCALE + 36) / 72);
       pango_layout_set_line_spacing (layout, 0.0);
     }
   if (opt_line_spacing >= 0.0)
@@ -360,6 +379,9 @@ do_output (PangoContext     *context,
 
   pango_context_set_matrix (context, orig_matrix);
   pango_matrix_free (orig_matrix);
+  int w, h;
+  pango_layout_get_size (layout, &w, &h);
+  g_print ("layout %d %d\n", w, h);
   g_object_unref (layout);
 }
 
@@ -829,6 +851,8 @@ parse_options (int argc, char *argv[])
      "Deprecated",		      "file"},
     {"pixels",		0, 0, G_OPTION_ARG_NONE,			&opt_pixels,
      "Use pixel units instead of points (sets dpi to 72)",		NULL},
+    {"pango-units",	0, 0, G_OPTION_ARG_NONE,			&opt_pango_units,
+     "Use Pango units instead of points",		                NULL},
     {"rtl",		0, 0, G_OPTION_ARG_NONE,			&opt_rtl,
      "Set base direction to right-to-left",				NULL},
     {"rotate",		0, 0, G_OPTION_ARG_DOUBLE,			&opt_rotate,