completed zoom tool

app/panel/timeline/timeline.cpp

@@ -40,6 +40,7 @@ TimelinePanel::TimelinePanel(QWidget *parent) :
   layout->addWidget(view_);
 
   connect(view_->horizontalScrollBar(), SIGNAL(valueChanged(int)), ruler_, SLOT(SetScroll(int)));
+  connect(view_, SIGNAL(UserSetScale(double)), this, SLOT(SetScale(double)));
   connect(ruler_, SIGNAL(TimeChanged(const int64_t&)), view_, SLOT(SetTime(const int64_t&)));
 
   // FIXME: Magic number

app/panel/timeline/timeline.h

@@ -49,13 +49,14 @@ signals:
 private:
   void Retranslate();
 
-  void SetScale(double scale);
-
   TimelineView* view_;
 
   TimeRuler* ruler_;
 
   double scale_;
+
+private slots:
+  void SetScale(double scale);
 };
 
 #endif // TIMELINE_PANEL_H

app/widget/timelineview/timelineview.h

@@ -63,6 +63,8 @@ signals:
   void RequestReplaceBlock(Block* old, Block* replace, int track);
   void RequestSplitAtTime(rational time, int track);
 
+  void UserSetScale(double scale);
+
 protected:
   virtual void mousePressEvent(QMouseEvent *event) override;
   virtual void mouseMoveEvent(QMouseEvent *event) override;

app/widget/timelineview/tool/zoom.cpp

@@ -39,9 +39,9 @@ void TimelineView::ZoomTool::MouseRelease(QMouseEvent *event)
 {
   if (event->modifiers() & Qt::AltModifier) {
     // Zoom out if the user clicks while holding Alt
-    parent()->SetScale(parent()->scale_ * 0.5);
+    emit parent()->UserSetScale(parent()->scale_ * 0.5);
   } else {
     // Otherwise zoom in
-    parent()->SetScale(parent()->scale_ * 2);
+    emit parent()->UserSetScale(parent()->scale_ * 2);
   }
 }