[meld] sourceview, preferences: Migrate to new GtkSourceView space-drawer API

[Kai Willadsen <kaiw src gnome org>]

commit f57cdd66f076273b14aef13d25694906c5833418
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Jul 14 07:17:25 2019 +1000

    sourceview, preferences: Migrate to new GtkSourceView space-drawer API
    
    The old whitespace display API goes away in 4.0, so this is necessary.
    There's no migration from the existing draw-spaces preference, but
    honestly it's one tick box, so I can live with this.

 data/org.gnome.meld.gschema.xml  |  8 ++++----
 meld/preferences.py              | 10 +---------
 meld/resources/ui/preferences.ui |  1 -
 meld/sourceview.py               | 17 +++--------------
 4 files changed, 8 insertions(+), 28 deletions(-)
---
diff --git a/data/org.gnome.meld.gschema.xml b/data/org.gnome.meld.gschema.xml
index 094d7089..b91b69f1 100644
--- a/data/org.gnome.meld.gschema.xml
+++ b/data/org.gnome.meld.gschema.xml
@@ -86,10 +86,10 @@
           <summary>Color scheme to use for syntax highlighting</summary>
           <description>Used by GtkSourceView to determine colors for syntax highlighting</description>
       </key>
-      <key name="draw-spaces" flags='org.gnome.meld.spacesflags'>
-          <default>[]</default>
-          <summary>Displayed whitespace</summary>
-          <description>Selector for individual whitespace character types to be shown. Possible values are 
'space', 'tab', 'newline' and 'nbsp'.</description>
+      <key name="enable-space-drawer" type='b'>
+          <default>false</default>
+          <summary>Draw whitespace</summary>
+          <description>If true, whitespace characters will be drawn in comparisons even if they are not in a 
changed area.</description>
       </key>
       <key name="wrap-mode" enum='org.gnome.meld.wrapmode'>
           <aliases>
diff --git a/meld/preferences.py b/meld/preferences.py
index 323ab43d..2f6aca55 100644
--- a/meld/preferences.py
+++ b/meld/preferences.py
@@ -301,6 +301,7 @@ class PreferencesDialog(Gtk.Dialog):
             ('highlight-current-line', self.checkbutton_highlight_current_line, 'active'),  # noqa: E501
             ('show-line-numbers', self.checkbutton_show_line_numbers, 'active'),  # noqa: E501
             ('highlight-syntax', self.checkbutton_use_syntax_highlighting, 'active'),  # noqa: E501
+            ('enable-space-drawer', self.checkbutton_show_whitespace, 'active'),  # noqa: E501
             ('use-system-editor', self.system_editor_checkbutton, 'active'),
             ('custom-editor-command', self.custom_edit_command_entry, 'text'),
             ('folder-shallow-comparison', self.checkbutton_shallow_compare, 'active'),  # noqa: E501
@@ -333,10 +334,6 @@ class PreferencesDialog(Gtk.Dialog):
             'active', self.checkbutton_wrap_word, 'sensitive',
             GObject.BindingFlags.DEFAULT)
 
-        # TODO: Fix once bind_with_mapping is available
-        self.checkbutton_show_whitespace.set_active(
-            bool(settings.get_flags('draw-spaces')))
-
         wrap_mode = settings.get_enum('wrap-mode')
         self.checkbutton_wrap_text.set_active(wrap_mode != Gtk.WrapMode.NONE)
         self.checkbutton_wrap_word.set_active(wrap_mode == Gtk.WrapMode.WORD)
@@ -380,11 +377,6 @@ class PreferencesDialog(Gtk.Dialog):
             wrap_mode = Gtk.WrapMode.CHAR
         settings.set_enum('wrap-mode', wrap_mode)
 
-    @Template.Callback()
-    def on_checkbutton_show_whitespace_toggled(self, widget):
-        value = GtkSource.DrawSpacesFlags.ALL if widget.get_active() else 0
-        settings.set_flags('draw-spaces', value)
-
     @Template.Callback()
     def on_response(self, dialog, response_id):
         self.destroy()
diff --git a/meld/resources/ui/preferences.ui b/meld/resources/ui/preferences.ui
index 9ba43d71..37dc3055 100644
--- a/meld/resources/ui/preferences.ui
+++ b/meld/resources/ui/preferences.ui
@@ -369,7 +369,6 @@
                                 <property name="use_underline">True</property>
                                 <property name="xalign">0</property>
                                 <property name="draw_indicator">True</property>
-                                <signal name="toggled" handler="on_checkbutton_show_whitespace_toggled" 
swapped="no"/>
                               </object>
                               <packing>
                                 <property name="expand">False</property>
diff --git a/meld/sourceview.py b/meld/sourceview.py
index 54641d6a..7daf9d2e 100644
--- a/meld/sourceview.py
+++ b/meld/sourceview.py
@@ -112,7 +112,7 @@ class MeldSourceView(GtkSource.View, SourceViewHelperMixin):
         ('highlight-current-line', 'highlight-current-line-local'),
         ('indent-width', 'tab-width'),
         ('insert-spaces-instead-of-tabs', 'insert-spaces-instead-of-tabs'),
-        ('draw-spaces', 'draw-spaces'),
+        ('enable-space-drawer', 'draw-spaces-bool'),
         ('wrap-mode', 'wrap-mode'),
         ('show-line-numbers', 'show-line-numbers'),
     )
@@ -273,20 +273,10 @@ class MeldSourceView(GtkSource.View, SourceViewHelperMixin):
         )
         self.wrap_mode_bool = wrap_mode_to_bool(None, self.props.wrap_mode)
 
-        def draw_spaces_from_bool(binding, from_value):
-            return GtkSource.DrawSpacesFlags.ALL if from_value else 0
-
-        def draw_spaces_to_bool(binding, from_value):
-            return bool(from_value)
-
         self.bind_property(
-            'draw-spaces-bool', self, 'draw-spaces',
-            GObject.BindingFlags.BIDIRECTIONAL,
-            draw_spaces_from_bool,
-            draw_spaces_to_bool,
+            'draw-spaces-bool', self.props.space_drawer, 'enable-matrix',
+            GObject.BindingFlags.DEFAULT | GObject.BindingFlags.SYNC_CREATE,
         )
-        self.draw_spaces_bool = draw_spaces_to_bool(
-            None, self.props.draw_spaces)
 
         meld_settings = get_meld_settings()
 
@@ -406,7 +396,6 @@ class CommitMessageSourceView(GtkSource.View):
     __gsettings_bindings__ = (
         ('indent-width', 'tab-width'),
         ('insert-spaces-instead-of-tabs', 'insert-spaces-instead-of-tabs'),
-        ('draw-spaces', 'draw-spaces'),
     )