content/browser/renderer_host/input/motion_event_android.h

// Copyright 2014 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 CONTENT_BROWSER_RENDERER_HOST_INPUT_MOTION_EVENT_ANDROID_H_
#define CONTENT_BROWSER_RENDERER_HOST_INPUT_MOTION_EVENT_ANDROID_H_

#include <jni.h>

#include "base/android/scoped_java_ref.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "content/common/content_export.h"
#include "ui/events/gesture_detection/motion_event.h"
#include "ui/gfx/geometry/point_f.h"

namespace content {

// Implementation of ui::MotionEvent wrapping a native Android MotionEvent.
// All *input* coordinates are in device pixels (as with Android MotionEvent),
// while all *output* coordinates are in DIPs (as with WebTouchEvent).
class CONTENT_EXPORT MotionEventAndroid : public ui::MotionEvent {
 public:
  struct Pointer {
    Pointer(jint id,
            jfloat pos_x_pixels,
            jfloat pos_y_pixels,
            jfloat touch_major_pixels,
            jfloat touch_minor_pixels,
            jfloat orientation_rad,
            jint tool_type);
    jint id;
    jfloat pos_x_pixels;
    jfloat pos_y_pixels;
    jfloat touch_major_pixels;
    jfloat touch_minor_pixels;
    jfloat orientation_rad;
    jint tool_type;
  };

  // Forcing the caller to provide all cached values upon construction
  // eliminates the need to perform a JNI call to retrieve values individually.
  MotionEventAndroid(float pix_to_dip,
                     JNIEnv* env,
                     jobject event,
                     jlong time_ms,
                     jint android_action,
                     jint pointer_count,
                     jint history_size,
                     jint action_index,
                     jint android_button_state,
                     jint meta_state,
                     jfloat raw_offset_x_pixels,
                     jfloat raw_offset_y_pixels,
                     const Pointer& pointer0,
                     const Pointer& pointer1);
  ~MotionEventAndroid() override;

  // ui::MotionEvent methods.
  int GetId() const override;
  Action GetAction() const override;
  int GetActionIndex() const override;
  size_t GetPointerCount() const override;
  int GetPointerId(size_t pointer_index) const override;
  float GetX(size_t pointer_index) const override;
  float GetY(size_t pointer_index) const override;
  float GetRawX(size_t pointer_index) const override;
  float GetRawY(size_t pointer_index) const override;
  float GetTouchMajor(size_t pointer_index) const override;
  float GetTouchMinor(size_t pointer_index) const override;
  float GetOrientation(size_t pointer_index) const override;
  float GetPressure(size_t pointer_index) const override;
  base::TimeTicks GetEventTime() const override;
  size_t GetHistorySize() const override;
  base::TimeTicks GetHistoricalEventTime(
      size_t historical_index) const override;
  float GetHistoricalTouchMajor(size_t pointer_index,
                                size_t historical_index) const override;
  float GetHistoricalX(size_t pointer_index,
                       size_t historical_index) const override;
  float GetHistoricalY(size_t pointer_index,
                       size_t historical_index) const override;
  ToolType GetToolType(size_t pointer_index) const override;
  int GetButtonState() const override;
  int GetFlags() const override;

  static bool RegisterMotionEventAndroid(JNIEnv* env);

 private:
  struct CachedPointer;

  float ToDips(float pixels) const;
  CachedPointer FromAndroidPointer(const Pointer& pointer) const;

  // Cache pointer coords, id's and major lengths for the most common
  // touch-related scenarios, i.e., scrolling and pinching.  This prevents
  // redundant JNI fetches for the same bits.
  enum { MAX_POINTERS_TO_CACHE = 2 };

  // The Java reference to the underlying MotionEvent.
  base::android::ScopedJavaGlobalRef<jobject> event_;

  // Used to convert pixel coordinates from the Java-backed MotionEvent to
  // DIP coordinates cached/returned by the MotionEventAndroid.
  const float pix_to_dip_;

  const base::TimeTicks cached_time_;
  const Action cached_action_;
  const size_t cached_pointer_count_;
  const size_t cached_history_size_;
  const int cached_action_index_;
  const int cached_button_state_;
  const int cached_flags_;
  const gfx::Vector2dF cached_raw_position_offset_;
  struct CachedPointer {
    CachedPointer();
    int id;
    gfx::PointF position;
    float touch_major;
    float touch_minor;
    float orientation;
    ToolType tool_type;
  } cached_pointers_[MAX_POINTERS_TO_CACHE];

  DISALLOW_COPY_AND_ASSIGN(MotionEventAndroid);
};

}  // namespace content

#endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_MOTION_EVENT_ANDROID_H_