[iagno] Add the highlight-turnable-tiles settings.

[Arnaud B. <arnaudb src gnome org>]

commit 196c58409cdba0375cdda27e390d11a7c7861ddb
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Sun Jul 14 18:31:50 2019 +0200

    Add the highlight-turnable-tiles settings.
    
    This function is mostly
    for newbies, so disable
    it by default and add a
    switch for toggling it.

 data/org.gnome.Reversi.gschema.xml | 7 +++++++
 data/ui/iagno.ui                   | 5 +++++
 src/game-view.vala                 | 6 +++++-
 src/iagno.vala                     | 2 ++
 4 files changed, 19 insertions(+), 1 deletion(-)
---
diff --git a/data/org.gnome.Reversi.gschema.xml b/data/org.gnome.Reversi.gschema.xml
index 729cb52..a2c4d36 100644
--- a/data/org.gnome.Reversi.gschema.xml
+++ b/data/org.gnome.Reversi.gschema.xml
@@ -27,6 +27,13 @@
       <!-- Translators: description of a settings key, see 'dconf-editor /org/gnome/iagno/color' -->
       <description>Whether to play as Dark or Light. Ignored for two-player games.</description>
     </key>
+    <key name="highlight-turnable-tiles" type="b">
+      <default>false</default>
+      <!-- Translators: summary of a settings key, see 'dconf-editor 
/org/gnome/iagno/highlight-turnable-tiles' -->
+      <summary>A flag to highlight turnable tiles</summary>
+      <!-- Translators: description of a settings key, see 'dconf-editor 
/org/gnome/iagno/highlight-turnable-tiles' -->
+      <description>If “true”, the tiles that will be captured to the opponent by a ply are 
highlighted.</description>
+    </key>
     <key name="theme" type="s">
       <default>'default'</default>
       <!-- Translators: summary of a settings key, see 'dconf-editor /org/gnome/iagno/theme' -->
diff --git a/data/ui/iagno.ui b/data/ui/iagno.ui
index fe99945..3477d74 100644
--- a/data/ui/iagno.ui
+++ b/data/ui/iagno.ui
@@ -28,6 +28,11 @@
         <attribute name="label" translatable="yes">A_ppearance</attribute>
         <attribute name="action">app.theme</attribute>
       </item>
+      <item>
+        <!-- Translators: hamburger menu entry; highlight-turnable-tiles togglebutton (with a mnemonic that 
appears pressing Alt) -->
+        <attribute name="label" translatable="yes">Highlight _turnable tiles</attribute>
+        <attribute name="action">app.highlight-turnable-tiles</attribute>
+      </item>
       <item>
         <!-- Translators: hamburger menu entry; sound togglebutton (with a mnemonic that appears pressing 
Alt) -->
         <attribute name="label" translatable="yes">_Sound</attribute>
diff --git a/src/game-view.vala b/src/game-view.vala
index 59fda65..a82b07d 100644
--- a/src/game-view.vala
+++ b/src/game-view.vala
@@ -22,6 +22,8 @@
 
 private class GameView : Gtk.DrawingArea
 {
+    internal bool show_turnable_tiles { private get; internal set; default = false; }
+
     private Gtk.DrawingArea _scoreboard;
     [CCode (notify = false)] internal Gtk.DrawingArea scoreboard {
         private get { return _scoreboard; }
@@ -494,7 +496,9 @@ private class GameView : Gtk.DrawingArea
                 return;
         }
         highlight_tile (cr, x, y, highlight_state, /* soft highlight */ false);
-        if (test_placing_tile && !(iagno_instance.computer != null && iagno_instance.player_one != 
game.current_color))
+        if (test_placing_tile
+         && show_turnable_tiles
+         && !(iagno_instance.computer != null && iagno_instance.player_one != game.current_color))
         {
             highlight_turnable_tiles (cr, move.x, move.y,  0, -1, move.n_tiles_n );
             highlight_turnable_tiles (cr, move.x, move.y,  1, -1, move.n_tiles_ne);
diff --git a/src/iagno.vala b/src/iagno.vala
index fa62579..f2c1a29 100644
--- a/src/iagno.vala
+++ b/src/iagno.vala
@@ -254,6 +254,8 @@ private class Iagno : Gtk.Application
         add_action (settings.create_action ("color"));
         add_action (settings.create_action ("num-players"));
         add_action (settings.create_action ("computer-level"));
+        add_action (settings.create_action ("highlight-turnable-tiles"));
+        settings.bind ("highlight-turnable-tiles", view, "show-turnable-tiles", SettingsBindFlags.GET);
 
         Box level_box = (Box) builder.get_object ("difficulty-box");
         Box color_box = (Box) builder.get_object ("color-box");