Implement PointerEvent#dx

sky/engine/core/events/PointerEvent.h

Index: sky/engine/core/events/PointerEvent.h
diff --git a/sky/engine/core/events/PointerEvent.h b/sky/engine/core/events/PointerEvent.h
index fc2f624f00d388b82f4a228b2097180f49b4616b..f23ec73d7d7a26a326525d2ce6787dc5eabf5433 100644
--- a/sky/engine/core/events/PointerEvent.h
+++ b/sky/engine/core/events/PointerEvent.h
@@ -77,6 +77,9 @@ public:
     double orientation() const { return m_orientation; }
     double tilt() const { return m_tilt; }
 
+    void setDX(double dx) { m_dx = dx; }
+    void setDY(double dy) { m_dy = dy; }
+
 private:
     PointerEvent();
     explicit PointerEvent(const WebPointerEvent& event);