implemented bulk of curve editor's functionality

While certainly not entirely complete yet, this implements most of the UI
functionality of the graph editor.

app/widget/curvewidget/curveview.h

@@ -1,6 +1,8 @@
 #ifndef CURVEVIEW_H
 #define CURVEVIEW_H
 
+#include "node/keyframe.h"
+#include "widget/keyframeview/keyframeviewitem.h"
 #include "widget/timelinewidget/view/timelineviewbase.h"
 
 class CurveView : public TimelineViewBase
@@ -8,12 +10,42 @@ class CurveView : public TimelineViewBase
 public:
   CurveView(QWidget* parent = nullptr);
 
+  void Clear();
+
+  void SetXScale(const double& x_scale);
+
+  void SetYScale(const double& y_scale);
+
+public slots:
+  void AddKeyframe(NodeKeyframePtr key);
+
+  void RemoveKeyframe(NodeKeyframePtr key);
+
 protected:
   virtual void drawBackground(QPainter* painter, const QRectF& rect) override;
 
 private:
+  QList<NodeKeyframe*> GetKeyframesSortedByTime();
+
+  qreal GetItemYFromKeyframeValue(NodeKeyframe* key);
+
+  void SetItemYFromKeyframeValue(NodeKeyframe* key, KeyframeViewItem* item);
+
+  void AdjustLines();
+
   int text_padding_;
 
+  double y_scale_;
+
+  int minimum_grid_space_;
+
+  QMap<NodeKeyframe*, KeyframeViewItem*> key_item_map_;
+
+  QList<QGraphicsLineItem*> lines_;
+
+private slots:
+  void KeyframeValueChanged();
+
 };
 
 #endif // CURVEVIEW_H