exo: Implement support for zwp_stylus_v1 protocol

components/exo/pointer_stylus_delegate.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_EXO_POINTER_STYLUS_DELEGATE_H_
+#define COMPONENTS_EXO_POINTER_STYLUS_DELEGATE_H_
+
+#include "base/time/time.h"
+#include "ui/events/event_constants.h"
+
+namespace gfx {
+class Vector2dF;
+}
+
+namespace exo {
+class Pointer;
+
+// Handles tool-specific event details on pointers. Used as an extension to the
+// PointerDelegate.
+class PointerStylusDelegate {
+ public:
+  // Called at the top of the pointer's destructor, to give observers a
+  // chance to remove themselves.
+  virtual void OnPointerDestroying(Pointer* pointer) = 0;
+
+  // Called when the type of pointer device changes.
+  virtual void OnPointerToolChange(ui::EventPointerType type) = 0;
+
+  // Called when the force (pressure) of the pointer changes.
+  // Normalized to be [0, 1].
+  virtual void OnPointerForce(base::TimeTicks time_stamp, float force) = 0;
+
+  // Called when the tilt of a pen/stylus changes. Measured from surface normal
+  // as plane angle in degrees, values lie in [-90,90]. A positive x is to the
+  // right and a positive y is towards the user.
+  virtual void OnPointerTilt(base::TimeTicks time_stamp,
+                             gfx::Vector2dF tilt) = 0;
+
+ protected:
+  virtual ~PointerStylusDelegate() {}
+};
+
+}  // namespace exo
+
+#endif  // COMPONENTS_EXO_POINTER_STYLUS_DELEGATE_H_