Disable undo action when it's nothing to undo

svn path=/branches/work/kreversi_rewrite/; revision=574325

kreversigame.h

@@ -87,6 +87,10 @@ public:
      *  Undoes the last player-computer move pair
      */
     void undo();
+    /**
+     *  @return if undo is possible
+     */
+    bool canUndo() const { return !m_undoStack.isEmpty(); }
     /**
      *  Returns a hint to current player
      */

mainwindow.cpp

@@ -32,7 +32,8 @@ void KReversiMainWindow::setupActions()
 {
     KAction *newGameAct = KStdAction::openNew(this, SLOT(slotNewGame()), actionCollection(), "new_game");
     KAction *quitAct = KStdAction::quit(this, SLOT(close()), actionCollection(), "quit");
-    KAction *undoAct = KStdAction::undo( this, SLOT(slotUndo()), actionCollection(), "undo" );
+    m_undoAct = KStdAction::undo( this, SLOT(slotUndo()), actionCollection(), "undo" );
+    m_undoAct->setEnabled( false ); // nothing to undo at the start of the game
     KAction *hintAct = new KAction( KIcon("wizard"), i18n("Hint"), actionCollection(), "hint" );
     hintAct->setShortcut( Qt::Key_H );
     connect( hintAct, SIGNAL(triggered(bool)), m_scene, SLOT(slotHint()) );
@@ -59,7 +60,7 @@ void KReversiMainWindow::setupActions()
 
     addAction(newGameAct);
     addAction(quitAct);
-    addAction(undoAct);
+    addAction(m_undoAct);
     addAction(hintAct);
 }
 
@@ -82,6 +83,7 @@ void KReversiMainWindow::slotNewGame()
 {
     delete m_game;
     m_game = new KReversiGame;
+    connect( m_game, SIGNAL(moveFinished()), SLOT(slotMoveFinished()) );
 
     if(m_scene == 0) // if called first time
     {
@@ -94,11 +96,19 @@ void KReversiMainWindow::slotNewGame()
     }
 }
 
+void KReversiMainWindow::slotMoveFinished()
+{
+    m_undoAct->setEnabled( m_game->canUndo() );    
+}
+
 void KReversiMainWindow::slotUndo()
 {
     if( !m_scene->isBusy() )
+    {
         // scene will automatically notice that it needs to update
         m_game->undo();
+        m_undoAct->setEnabled( m_game->canUndo() );    
+    }
 }
 
 #include "mainwindow.moc"

mainwindow.h

@@ -17,11 +17,14 @@ public slots:
     void slotNewGame();
     void slotBackgroundChanged(const QString& text);
     void slotUndo();
+    void slotMoveFinished();
 private:
     void setupActions();
 
     KReversiScene *m_scene;
     KReversiView  *m_view;
     KReversiGame *m_game;
+
+    KAction* m_undoAct;
 };
 #endif