adding color picking on iOS

engine/canvas_modes.h

@@ -35,13 +35,13 @@ public:
 class CanvasModePen : public CanvasMode
 {
     bool m_dragging = false;
-    bool m_picking = false;
     glm::vec2 m_pan_start;
     float m_camera_fov;
     float m_zoom_canvas = 1.f;
     float m_zoom_start;
 public:
     virtual void on_MouseEvent(MouseEvent* me, glm::vec2& loc) override;
+    bool m_picking = false;
 };
 
 class CanvasModeLine : public CanvasMode