[gtk+] TextView—Fix inverted movements by arrows in RTL

[Daniel Boles <dboles src gnome org>]

commit 0128b8d33f47c9387ee342a1158f3038e02eff49
Author: Daniel Boles <dboles src gnome org>
Date:   Sat Feb 18 22:50:00 2017 +0000

    TextView—Fix inverted movements by arrows in RTL
    
    Using Ctrl + left/right to skip between words, or left/right to cancel a
    selection, were causing movement on the screen in the opposite direction
    of the glyph on the key. This was surprising and awful UX for RTL users.
    
    This is based on a patch covering the former case by:
    Author:    Mehdi Sadeghi <mehdi mehdix org>
    Date:      Sat Feb 18 02:16:00 2017 +0000
    
    https://bugzilla.gnome.org/show_bug.cgi?id=136059

 gtk/gtktextview.c |   20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtktextview.c b/gtk/gtktextview.c
index 7f4f79a..1ab5f47 100644
--- a/gtk/gtktextview.c
+++ b/gtk/gtktextview.c
@@ -6343,6 +6343,17 @@ move_cursor (GtkTextView       *text_view,
   gtk_text_view_check_cursor_blink (text_view);
 }
 
+static gboolean
+iter_line_is_rtl (GtkTextIter *iter, GtkTextLayout *layout)
+{
+  GtkTextLine *line = _gtk_text_iter_get_text_line (iter);
+  GtkTextLineDisplay *display = gtk_text_layout_get_line_display (layout, line, FALSE);
+  const gchar *text = pango_layout_get_text (display->layout);
+  PangoDirection pango_dir = pango_find_base_dir (text, -1);
+
+  return pango_dir == PANGO_DIRECTION_RTL;
+}
+
 static void
 gtk_text_view_move_cursor (GtkTextView     *text_view,
                            GtkMovementStep  step,
@@ -6437,15 +6448,19 @@ gtk_text_view_move_cursor (GtkTextView     *text_view,
 
   if (! extend_selection)
     {
+      gboolean move_forward = count > 0;
       GtkTextIter sel_bound;
 
       gtk_text_buffer_get_iter_at_mark (get_buffer (text_view), &sel_bound,
                                         gtk_text_buffer_get_selection_bound (get_buffer (text_view)));
 
+      if (iter_line_is_rtl (&insert, priv->layout))
+        move_forward = !move_forward;
+
       /* if we move forward, assume the cursor is at the end of the selection;
        * if we move backward, assume the cursor is at the start
        */
-      if (count > 0)
+      if (move_forward)
         gtk_text_iter_order (&sel_bound, &insert);
       else
         gtk_text_iter_order (&insert, &sel_bound);
@@ -6477,6 +6492,9 @@ gtk_text_view_move_cursor (GtkTextView     *text_view,
       break;
 
     case GTK_MOVEMENT_WORDS:
+      if (iter_line_is_rtl (&newplace, priv->layout))
+        count *= -1;
+
       if (count < 0)
         gtk_text_iter_backward_visible_word_starts (&newplace, -count);
       else if (count > 0)