implement canvas touch lock

engine/event.h

@@ -47,6 +47,13 @@ enum class kEventType : uint8_t
     ButtonUp,
 };
 
+enum class kEventSource : uint8_t
+{
+    Mouse,
+    Touch,
+    Stylus,
+};
+
 class Event
 {
 public:
@@ -59,8 +66,9 @@ class MouseEvent : public Event
 public:
     MouseEvent() { m_cat = kEventCategory::MouseEvent; }
     glm::vec2 m_pos;
-    float m_pressure;
-    float m_scroll_delta;
+    float m_pressure = 0;
+    float m_scroll_delta = 0;
+    kEventSource m_source = kEventSource::Mouse;
 };
 
 class KeyEvent : public Event