[gspell/wip/fix-constant-redrawing] inline-checker-text-buffer: fix constant redrawing

[Sébastien Wilmet <swilmet src gnome org>]

commit f15e106336b3144515f3d63f18e42b08953fd1e4
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sat Jul 9 13:56:19 2016 +0200

    inline-checker-text-buffer: fix constant redrawing
    
    When check_current_word was FALSE, the GtkTextView was constantly
    redrawn. For two reasons:
    - because gtk_text_buffer_remove_tag() was called on the current word,
      even if the tag was not present. Which always queued a redraw.
    - because of the queue_draw() hack, which was also always called when
      check_current_word is FALSE.
    
    So, for the current word handling, do the queue_draw() hack only if the
    tag is removed. And remove the tag only if the tag is present.
    
    Also, queue a redraw on all views, because if two views display the same
    region, only one view was redrawn since the scan_region is already empty
    for the second view.
    
    Thanks to Sebastian Keller for the bug report.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=768306

 gspell/gspell-inline-checker-text-buffer.c |   83 +++++++++++++++++++++------
 1 files changed, 64 insertions(+), 19 deletions(-)
---
diff --git a/gspell/gspell-inline-checker-text-buffer.c b/gspell/gspell-inline-checker-text-buffer.c
index 2da0e00..ef057e6 100644
--- a/gspell/gspell-inline-checker-text-buffer.c
+++ b/gspell/gspell-inline-checker-text-buffer.c
@@ -87,6 +87,58 @@ typedef enum
 
 G_DEFINE_TYPE (GspellInlineCheckerTextBuffer, _gspell_inline_checker_text_buffer, G_TYPE_OBJECT)
 
+/* FIXME properly. Workaround for bug in GtkTextView:
+ * https://bugzilla.gnome.org/show_bug.cgi?id=763741
+ */
+static void
+queue_draw_hack (GspellInlineCheckerTextBuffer *spell)
+{
+       GSList *l;
+
+       for (l = spell->views; l != NULL; l = l->next)
+       {
+               GtkWidget *view = GTK_WIDGET (l->data);
+               gtk_widget_queue_draw (view);
+       }
+}
+
+/* Remove the highlight_tag only if present. If gtk_text_buffer_remove_tag() is
+ * called when the tag is not present, GtkTextView anyway queues a redraw, which
+ * we want to avoid (it can lead to an infinite loop).
+ */
+static void
+remove_highlight_tag_if_present (GspellInlineCheckerTextBuffer *spell,
+                                const GtkTextIter             *start,
+                                const GtkTextIter             *end)
+{
+       gboolean remove = FALSE;
+
+       if (gtk_text_iter_has_tag (start, spell->highlight_tag))
+       {
+               remove = TRUE;
+       }
+       else
+       {
+               GtkTextIter iter = *start;
+
+               if (gtk_text_iter_forward_to_tag_toggle (&iter, spell->highlight_tag) &&
+                   gtk_text_iter_compare (&iter, end) < 0)
+               {
+                       remove = TRUE;
+               }
+       }
+
+       if (remove)
+       {
+               gtk_text_buffer_remove_tag (spell->buffer,
+                                           spell->highlight_tag,
+                                           start,
+                                           end);
+
+               queue_draw_hack (spell);
+       }
+}
+
 static void
 check_word (GspellInlineCheckerTextBuffer *spell,
            const GtkTextIter             *start,
@@ -315,8 +367,9 @@ check_visible_region_in_view (GspellInlineCheckerTextBuffer *spell,
                                              &visible_start,
                                              &visible_end);
 
-       if (intersect == NULL)
+       if (_gspell_region_is_empty (intersect))
        {
+               g_clear_object (&intersect);
                return;
        }
 
@@ -329,10 +382,9 @@ check_visible_region_in_view (GspellInlineCheckerTextBuffer *spell,
                                                 &current_word_start,
                                                 &current_word_end))
                {
-                       gtk_text_buffer_remove_tag (spell->buffer,
-                                                   spell->highlight_tag,
-                                                   &current_word_start,
-                                                   &current_word_end);
+                       remove_highlight_tag_if_present (spell,
+                                                        &current_word_start,
+                                                        &current_word_end);
 
                        _gspell_region_subtract (intersect,
                                                 &current_word_start,
@@ -344,13 +396,13 @@ check_visible_region_in_view (GspellInlineCheckerTextBuffer *spell,
                        _gspell_region_add (spell->scan_region,
                                            &current_word_start,
                                            &current_word_end);
-               }
-       }
 
-       if (_gspell_region_is_empty (intersect))
-       {
-               g_clear_object (&intersect);
-               goto out;
+                       if (_gspell_region_is_empty (intersect))
+                       {
+                               g_clear_object (&intersect);
+                               return;
+                       }
+               }
        }
 
        _gspell_region_get_start_region_iter (intersect, &intersect_iter);
@@ -391,14 +443,7 @@ check_visible_region_in_view (GspellInlineCheckerTextBuffer *spell,
                g_clear_object (&spell->scan_region);
        }
 
-out:
-       if (view != NULL)
-       {
-               /* FIXME properly. Workaround for bug in GtkTextView:
-                * https://bugzilla.gnome.org/show_bug.cgi?id=763741
-                */
-               gtk_widget_queue_draw (GTK_WIDGET (view));
-       }
+       queue_draw_hack (spell);
 }
 
 static void