path: root/mobile/android/geckoview/src/main/java/org/mozilla/geckoview/PanZoomController.java

/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.geckoview;

import android.app.UiModeManager;
import android.content.Context;
import android.content.res.Configuration;
import android.graphics.Rect;
import android.os.SystemClock;
import android.util.Log;
import android.util.Pair;
import android.view.InputDevice;
import android.view.MotionEvent;
import androidx.annotation.AnyThread;
import androidx.annotation.IntDef;
import androidx.annotation.NonNull;
import androidx.annotation.UiThread;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.ArrayList;
import org.mozilla.gecko.GeckoAppShell;
import org.mozilla.gecko.annotation.WrapForJNI;
import org.mozilla.gecko.mozglue.JNIObject;
import org.mozilla.gecko.util.GeckoBundle;
import org.mozilla.gecko.util.ThreadUtils;

@UiThread
public class PanZoomController {
  private static final String LOGTAG = "GeckoNPZC";
  private static final int EVENT_SOURCE_SCROLL = 0;
  private static final int EVENT_SOURCE_MOTION = 1;
  private static final int EVENT_SOURCE_MOUSE = 2;
  private static Boolean sTreatMouseAsTouch = null;

  private final GeckoSession mSession;
  private final Rect mTempRect = new Rect();
  private boolean mAttached;
  private float mPointerScrollFactor = 64.0f;
  private long mLastDownTime;

  @Retention(RetentionPolicy.SOURCE)
  @IntDef({SCROLL_BEHAVIOR_SMOOTH, SCROLL_BEHAVIOR_AUTO})
  public @interface ScrollBehaviorType {}

  /** Specifies smooth scrolling which animates content to the desired scroll position. */
  public static final int SCROLL_BEHAVIOR_SMOOTH = 0;

  /** Specifies auto scrolling which jumps content to the desired scroll position. */
  public static final int SCROLL_BEHAVIOR_AUTO = 1;

  @Retention(RetentionPolicy.SOURCE)
  @IntDef({
    INPUT_RESULT_UNHANDLED,
    INPUT_RESULT_HANDLED,
    INPUT_RESULT_HANDLED_CONTENT,
    INPUT_RESULT_IGNORED
  })
  public @interface InputResult {}

  /**
   * Specifies that an input event was not handled by the PanZoomController for a panning or zooming
   * operation. The event may have been handled by Web content or internally (e.g. text selection).
   */
  @WrapForJNI public static final int INPUT_RESULT_UNHANDLED = 0;

  /**
   * Specifies that an input event was handled by the PanZoomController for a panning or zooming
   * operation, but likely not by any touch event listeners in Web content.
   */
  @WrapForJNI public static final int INPUT_RESULT_HANDLED = 1;

  /**
   * Specifies that an input event was handled by the PanZoomController and passed on to touch event
   * listeners in Web content.
   */
  @WrapForJNI public static final int INPUT_RESULT_HANDLED_CONTENT = 2;

  /**
   * Specifies that an input event was consumed by a PanZoomController internally and browsers
   * should do nothing in response to the event.
   */
  @WrapForJNI public static final int INPUT_RESULT_IGNORED = 3;

  @Retention(RetentionPolicy.SOURCE)
  @IntDef(
      flag = true,
      value = {
        SCROLLABLE_FLAG_NONE,
        SCROLLABLE_FLAG_TOP,
        SCROLLABLE_FLAG_RIGHT,
        SCROLLABLE_FLAG_BOTTOM,
        SCROLLABLE_FLAG_LEFT
      })
  public @interface ScrollableDirections {}

  /**
   * Represents which directions can be scrolled in the scroll container where an input event was
   * handled. This value is only useful in the case of {@link
   * PanZoomController#INPUT_RESULT_HANDLED}.
   */
  /* The container cannot be scrolled. */
  @WrapForJNI public static final int SCROLLABLE_FLAG_NONE = 0;

  /* The container cannot be scrolled to top */
  @WrapForJNI public static final int SCROLLABLE_FLAG_TOP = 1 << 0;
  /* The container cannot be scrolled to right */
  @WrapForJNI public static final int SCROLLABLE_FLAG_RIGHT = 1 << 1;
  /* The container cannot be scrolled to bottom */
  @WrapForJNI public static final int SCROLLABLE_FLAG_BOTTOM = 1 << 2;
  /* The container cannot be scrolled to left */
  @WrapForJNI public static final int SCROLLABLE_FLAG_LEFT = 1 << 3;

  @Retention(RetentionPolicy.SOURCE)
  @IntDef(
      flag = true,
      value = {OVERSCROLL_FLAG_NONE, OVERSCROLL_FLAG_HORIZONTAL, OVERSCROLL_FLAG_VERTICAL})
  public @interface OverscrollDirections {}

  /**
   * Represents which directions can be over-scrolled in the scroll container where an input event
   * was handled. This value is only useful in the case of {@link
   * PanZoomController#INPUT_RESULT_HANDLED}.
   */
  /* the container cannot be over-scrolled. */
  @WrapForJNI public static final int OVERSCROLL_FLAG_NONE = 0;

  /* the container can be over-scrolled horizontally. */
  @WrapForJNI public static final int OVERSCROLL_FLAG_HORIZONTAL = 1 << 0;
  /* the container can be over-scrolled vertically. */
  @WrapForJNI public static final int OVERSCROLL_FLAG_VERTICAL = 1 << 1;

  /**
   * Represents how a {@link MotionEvent} was handled in Gecko. This value can be used by browser
   * apps to implement features like pull-to-refresh. Failing to account this value might break some
   * websites expectations about touch events.
   *
   * <p>For example, a {@link PanZoomController.InputResultDetail#handledResult} value of {@link
   * PanZoomController#INPUT_RESULT_HANDLED} and {@link
   * PanZoomController.InputResultDetail#overscrollDirections} of {@link
   * PanZoomController#OVERSCROLL_FLAG_NONE} indicates that the event was consumed for a panning or
   * zooming operation and that the website does not expect the browser to react to the touch event
   * (say, by triggering the pull-to-refresh feature) even though the scroll container reached to
   * the edge.
   */
  @WrapForJNI
  public static class InputResultDetail {
    protected InputResultDetail(
        final @InputResult int handledResult,
        final @ScrollableDirections int scrollableDirections,
        final @OverscrollDirections int overscrollDirections) {
      mHandledResult = handledResult;
      mScrollableDirections = scrollableDirections;
      mOverscrollDirections = overscrollDirections;
    }

    /**
     * @return One of the {@link #INPUT_RESULT_UNHANDLED INPUT_RESULT_*} indicating how the event
     *     was handled.
     */
    @AnyThread
    public @InputResult int handledResult() {
      return mHandledResult;
    }

    /**
     * @return an OR-ed value of {@link #SCROLLABLE_FLAG_NONE SCROLLABLE_FLAG_*} indicating which
     *     directions can be scrollable.
     */
    @AnyThread
    public @ScrollableDirections int scrollableDirections() {
      return mScrollableDirections;
    }

    /**
     * @return an OR-ed value of {@link #OVERSCROLL_FLAG_NONE OVERSCROLL_FLAG_*} indicating which
     *     directions can be over-scrollable.
     */
    @AnyThread
    public @OverscrollDirections int overscrollDirections() {
      return mOverscrollDirections;
    }

    private final @InputResult int mHandledResult;
    private final @ScrollableDirections int mScrollableDirections;
    private final @OverscrollDirections int mOverscrollDirections;
  }

  private SynthesizedEventState mPointerState;

  private ArrayList<Pair<Integer, MotionEvent>> mQueuedEvents;

  private boolean mSynthesizedEvent = false;

  @WrapForJNI
  private static class MotionEventData {
    public final int action;
    public final int actionIndex;
    public final long time;
    public final int metaState;
    public final int pointerId[];
    public final int historySize;
    public final long historicalTime[];
    public final float historicalX[];
    public final float historicalY[];
    public final float historicalOrientation[];
    public final float historicalPressure[];
    public final float historicalToolMajor[];
    public final float historicalToolMinor[];
    public final float x[];
    public final float y[];
    public final float orientation[];
    public final float pressure[];
    public final float toolMajor[];
    public final float toolMinor[];

    public MotionEventData(final MotionEvent event) {
      final int count = event.getPointerCount();
      action = event.getActionMasked();
      actionIndex = event.getActionIndex();
      time = event.getEventTime();
      metaState = event.getMetaState();
      historySize = event.getHistorySize();
      historicalTime = new long[historySize];
      historicalX = new float[historySize * count];
      historicalY = new float[historySize * count];
      historicalOrientation = new float[historySize * count];
      historicalPressure = new float[historySize * count];
      historicalToolMajor = new float[historySize * count];
      historicalToolMinor = new float[historySize * count];
      pointerId = new int[count];
      x = new float[count];
      y = new float[count];
      orientation = new float[count];
      pressure = new float[count];
      toolMajor = new float[count];
      toolMinor = new float[count];

      for (int historyIndex = 0; historyIndex < historySize; historyIndex++) {
        historicalTime[historyIndex] = event.getHistoricalEventTime(historyIndex);
      }

      final MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
      for (int i = 0; i < count; i++) {
        pointerId[i] = event.getPointerId(i);

        for (int historyIndex = 0; historyIndex < historySize; historyIndex++) {
          event.getHistoricalPointerCoords(i, historyIndex, coords);

          final int historicalI = historyIndex * count + i;
          historicalX[historicalI] = coords.x;
          historicalY[historicalI] = coords.y;

          historicalOrientation[historicalI] = coords.orientation;
          historicalPressure[historicalI] = coords.pressure;

          // If we are converting to CSS pixels, we should adjust the radii as well.
          historicalToolMajor[historicalI] = coords.toolMajor;
          historicalToolMinor[historicalI] = coords.toolMinor;
        }

        event.getPointerCoords(i, coords);

        x[i] = coords.x;
        y[i] = coords.y;

        orientation[i] = coords.orientation;
        pressure[i] = coords.pressure;

        // If we are converting to CSS pixels, we should adjust the radii as well.
        toolMajor[i] = coords.toolMajor;
        toolMinor[i] = coords.toolMinor;
      }
    }
  }

  /* package */ final class NativeProvider extends JNIObject {
    @Override // JNIObject
    protected void disposeNative() {
      // Disposal happens in native code.
      throw new UnsupportedOperationException();
    }

    @WrapForJNI(calledFrom = "ui")
    private native void handleMotionEvent(
        MotionEventData eventData,
        float screenX,
        float screenY,
        GeckoResult<InputResultDetail> result);

    @WrapForJNI(calledFrom = "ui")
    private native @InputResult int handleScrollEvent(
        long time, int metaState, float x, float y, float hScroll, float vScroll);

    @WrapForJNI(calledFrom = "ui")
    private native @InputResult int handleMouseEvent(
        int action, long time, int metaState, float x, float y, int buttons);

    @WrapForJNI(stubName = "SetIsLongpressEnabled") // Called from test thread.
    private native void nativeSetIsLongpressEnabled(boolean isLongpressEnabled);

    @WrapForJNI(calledFrom = "ui")
    private void synthesizeNativeTouchPoint(
        final int pointerId,
        final int eventType,
        final int clientX,
        final int clientY,
        final double pressure,
        final int orientation) {
      if (pointerId == PointerInfo.RESERVED_MOUSE_POINTER_ID) {
        throw new IllegalArgumentException("Pointer ID reserved for mouse");
      }
      synthesizeNativePointer(
          InputDevice.SOURCE_TOUCHSCREEN,
          pointerId,
          eventType,
          clientX,
          clientY,
          pressure,
          orientation,
          0);
    }

    @WrapForJNI(calledFrom = "ui")
    private void synthesizeNativeMouseEvent(
        final int eventType, final int clientX, final int clientY, final int button) {
      synthesizeNativePointer(
          InputDevice.SOURCE_MOUSE,
          PointerInfo.RESERVED_MOUSE_POINTER_ID,
          eventType,
          clientX,
          clientY,
          0,
          0,
          button);
    }

    @WrapForJNI(calledFrom = "ui")
    private void setAttached(final boolean attached) {
      if (attached) {
        mAttached = true;
        flushEventQueue();
      } else if (mAttached) {
        mAttached = false;
        enableEventQueue();
      }
    }
  }

  /* package */ final NativeProvider mNative = new NativeProvider();

  private void handleMotionEvent(final MotionEvent event) {
    handleMotionEvent(event, null);
  }

  private void handleMotionEvent(
      final MotionEvent event, final GeckoResult<InputResultDetail> result) {
    if (!mAttached) {
      mQueuedEvents.add(new Pair<>(EVENT_SOURCE_MOTION, event));
      if (result != null) {
        result.complete(
            new InputResultDetail(
                INPUT_RESULT_HANDLED, SCROLLABLE_FLAG_NONE, OVERSCROLL_FLAG_NONE));
      }
      return;
    }

    final int action = event.getActionMasked();

    if (action == MotionEvent.ACTION_DOWN) {
      mLastDownTime = event.getDownTime();
    } else if (mLastDownTime != event.getDownTime()) {
      if (result != null) {
        result.complete(
            new InputResultDetail(
                INPUT_RESULT_UNHANDLED, SCROLLABLE_FLAG_NONE, OVERSCROLL_FLAG_NONE));
      }
      return;
    }

    final float screenX = event.getRawX() - event.getX();
    final float screenY = event.getRawY() - event.getY();

    // Take this opportunity to update screen origin of session. This gets
    // dispatched to the gecko thread, so we also pass the new screen x/y directly to apz.
    // If this is a synthesized touch, the screen offset is bogus so ignore it.
    if (!mSynthesizedEvent) {
      mSession.onScreenOriginChanged((int) screenX, (int) screenY);
    }

    final MotionEventData data = new MotionEventData(event);
    mNative.handleMotionEvent(data, screenX, screenY, result);
  }

  private @InputResult int handleScrollEvent(final MotionEvent event) {
    if (!mAttached) {
      mQueuedEvents.add(new Pair<>(EVENT_SOURCE_SCROLL, event));
      return INPUT_RESULT_HANDLED;
    }

    final int count = event.getPointerCount();

    if (count <= 0) {
      return INPUT_RESULT_UNHANDLED;
    }

    final MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
    event.getPointerCoords(0, coords);

    // Translate surface origin to client origin for scroll events.
    mSession.getSurfaceBounds(mTempRect);
    final float x = coords.x - mTempRect.left;
    final float y = coords.y - mTempRect.top;

    final float hScroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL) * mPointerScrollFactor;
    final float vScroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL) * mPointerScrollFactor;

    return mNative.handleScrollEvent(
        event.getEventTime(), event.getMetaState(), x, y, hScroll, vScroll);
  }

  private @InputResult int handleMouseEvent(final MotionEvent event) {
    if (!mAttached) {
      mQueuedEvents.add(new Pair<>(EVENT_SOURCE_MOUSE, event));
      return INPUT_RESULT_UNHANDLED;
    }

    final int count = event.getPointerCount();

    if (count <= 0) {
      return INPUT_RESULT_UNHANDLED;
    }

    final MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
    event.getPointerCoords(0, coords);

    // Translate surface origin to client origin for mouse events.
    mSession.getSurfaceBounds(mTempRect);
    final float x = coords.x - mTempRect.left;
    final float y = coords.y - mTempRect.top;

    return mNative.handleMouseEvent(
        event.getActionMasked(),
        event.getEventTime(),
        event.getMetaState(),
        x,
        y,
        event.getButtonState());
  }

  protected PanZoomController(final GeckoSession session) {
    mSession = session;
    enableEventQueue();
  }

  private boolean treatMouseAsTouch() {
    if (sTreatMouseAsTouch == null) {
      final Context c = GeckoAppShell.getApplicationContext();
      if (c == null) {
        // This might happen if the GeckoRuntime has not been initialized yet.
        return false;
      }
      final UiModeManager m = (UiModeManager) c.getSystemService(Context.UI_MODE_SERVICE);
      // on TV devices, treat mouse as touch. everywhere else, don't
      sTreatMouseAsTouch = (m.getCurrentModeType() == Configuration.UI_MODE_TYPE_TELEVISION);
    }

    return sTreatMouseAsTouch;
  }

  /**
   * Set the current scroll factor. The scroll factor is the maximum scroll amount that one scroll
   * event may generate, in device pixels.
   *
   * @param factor Scroll factor.
   */
  public void setScrollFactor(final float factor) {
    ThreadUtils.assertOnUiThread();
    mPointerScrollFactor = factor;
  }

  /**
   * Get the current scroll factor.
   *
   * @return Scroll factor.
   */
  public float getScrollFactor() {
    ThreadUtils.assertOnUiThread();
    return mPointerScrollFactor;
  }

  /**
   * This is a workaround for touch pad on Android app by Chrome OS. Android app on Chrome OS fires
   * weird motion event by two finger scroll. See https://crbug.com/704051
   */
  private boolean mayTouchpadScroll(final @NonNull MotionEvent event) {
    final int action = event.getActionMasked();
    return event.getButtonState() == 0
        && (action == MotionEvent.ACTION_DOWN
            || (mLastDownTime == event.getDownTime()
                && (action == MotionEvent.ACTION_MOVE
                    || action == MotionEvent.ACTION_UP
                    || action == MotionEvent.ACTION_CANCEL)));
  }

  /**
   * Process a touch event through the pan-zoom controller. Treat any mouse events as "touch" rather
   * than as "mouse". Pointer coordinates should be relative to the display surface.
   *
   * @param event MotionEvent to process.
   */
  public void onTouchEvent(final @NonNull MotionEvent event) {
    ThreadUtils.assertOnUiThread();

    if (!treatMouseAsTouch()
        && event.getToolType(0) == MotionEvent.TOOL_TYPE_MOUSE
        && !mayTouchpadScroll(event)) {
      handleMouseEvent(event);
      return;
    }
    handleMotionEvent(event);
  }

  /**
   * Process a touch event through the pan-zoom controller. Treat any mouse events as "touch" rather
   * than as "mouse". Pointer coordinates should be relative to the display surface.
   *
   * <p>NOTE: It is highly recommended to only call this with ACTION_DOWN or in otherwise limited
   * capacity. Returning a GeckoResult for every touch event will generate a lot of allocations and
   * unnecessary GC pressure. Instead, prefer to call {@link #onTouchEvent(MotionEvent)}.
   *
   * @param event MotionEvent to process.
   * @return A GeckoResult resolving to {@link PanZoomController.InputResultDetail}).
   */
  public @NonNull GeckoResult<InputResultDetail> onTouchEventForDetailResult(
      final @NonNull MotionEvent event) {
    ThreadUtils.assertOnUiThread();

    if (!treatMouseAsTouch()
        && event.getToolType(0) == MotionEvent.TOOL_TYPE_MOUSE
        && !mayTouchpadScroll(event)) {
      return GeckoResult.fromValue(
          new InputResultDetail(
              handleMouseEvent(event), SCROLLABLE_FLAG_NONE, OVERSCROLL_FLAG_NONE));
    }

    final GeckoResult<InputResultDetail> result = new GeckoResult<>();
    handleMotionEvent(event, result);
    return result;
  }

  /**
   * Process a touch event through the pan-zoom controller. Treat any mouse events as "mouse" rather
   * than as "touch". Pointer coordinates should be relative to the display surface.
   *
   * @param event MotionEvent to process.
   */
  public void onMouseEvent(final @NonNull MotionEvent event) {
    ThreadUtils.assertOnUiThread();

    if (event.getToolType(0) == MotionEvent.TOOL_TYPE_MOUSE) {
      return;
    }
    handleMotionEvent(event);
  }

  @Override
  protected void finalize() throws Throwable {
    mNative.setAttached(false);
  }

  /**
   * Process a non-touch motion event through the pan-zoom controller. Currently, hover and scroll
   * events are supported. Pointer coordinates should be relative to the display surface.
   *
   * @param event MotionEvent to process.
   */
  public void onMotionEvent(final @NonNull MotionEvent event) {
    ThreadUtils.assertOnUiThread();

    final int action = event.getActionMasked();
    if (action == MotionEvent.ACTION_SCROLL) {
      if (event.getDownTime() >= mLastDownTime) {
        mLastDownTime = event.getDownTime();
      } else if ((InputDevice.getDevice(event.getDeviceId()) != null)
          && (InputDevice.getDevice(event.getDeviceId()).getSources() & InputDevice.SOURCE_TOUCHPAD)
              == InputDevice.SOURCE_TOUCHPAD) {
        return;
      }
      handleScrollEvent(event);
    } else if ((action == MotionEvent.ACTION_HOVER_MOVE)
        || (action == MotionEvent.ACTION_HOVER_ENTER)
        || (action == MotionEvent.ACTION_HOVER_EXIT)) {
      handleMouseEvent(event);
    }
  }

  private void enableEventQueue() {
    if (mQueuedEvents != null) {
      throw new IllegalStateException("Already have an event queue");
    }
    mQueuedEvents = new ArrayList<>();
  }

  private void flushEventQueue() {
    if (mQueuedEvents == null) {
      return;
    }

    final ArrayList<Pair<Integer, MotionEvent>> events = mQueuedEvents;
    mQueuedEvents = null;
    for (final Pair<Integer, MotionEvent> pair : events) {
      switch (pair.first) {
        case EVENT_SOURCE_MOTION:
          handleMotionEvent(pair.second);
          break;
        case EVENT_SOURCE_SCROLL:
          handleScrollEvent(pair.second);
          break;
        case EVENT_SOURCE_MOUSE:
          handleMouseEvent(pair.second);
          break;
      }
    }
  }

  /**
   * Set whether Gecko should generate long-press events.
   *
   * @param isLongpressEnabled True if Gecko should generate long-press events.
   */
  public void setIsLongpressEnabled(final boolean isLongpressEnabled) {
    ThreadUtils.assertOnUiThread();

    if (mAttached) {
      mNative.nativeSetIsLongpressEnabled(isLongpressEnabled);
    }
  }

  private static class PointerInfo {
    // We reserve one pointer ID for the mouse, so that tests don't have
    // to worry about tracking pointer IDs if they just want to test mouse
    // event synthesization. If somebody tries to use this ID for a
    // synthesized touch event we'll throw an exception.
    public static final int RESERVED_MOUSE_POINTER_ID = 100000;

    public int pointerId;
    public int source;
    public int surfaceX;
    public int surfaceY;
    public double pressure;
    public int orientation;
    public int buttonState;

    public MotionEvent.PointerCoords getCoords() {
      final MotionEvent.PointerCoords coords = new MotionEvent.PointerCoords();
      coords.orientation = orientation;
      coords.pressure = (float) pressure;
      coords.x = surfaceX;
      coords.y = surfaceY;
      return coords;
    }
  }

  private static class SynthesizedEventState {
    public final ArrayList<PointerInfo> pointers;
    public long downTime;

    SynthesizedEventState() {
      pointers = new ArrayList<PointerInfo>();
    }

    int getPointerIndex(final int pointerId) {
      for (int i = 0; i < pointers.size(); i++) {
        if (pointers.get(i).pointerId == pointerId) {
          return i;
        }
      }
      return -1;
    }

    int addPointer(final int pointerId, final int source) {
      final PointerInfo info = new PointerInfo();
      info.pointerId = pointerId;
      info.source = source;
      pointers.add(info);
      return pointers.size() - 1;
    }

    int getPointerCount(final int source) {
      int count = 0;
      for (int i = 0; i < pointers.size(); i++) {
        if (pointers.get(i).source == source) {
          count++;
        }
      }
      return count;
    }

    int getPointerButtonState(final int source) {
      for (int i = 0; i < pointers.size(); i++) {
        if (pointers.get(i).source == source) {
          return pointers.get(i).buttonState;
        }
      }
      return 0;
    }

    MotionEvent.PointerProperties[] getPointerProperties(final int source) {
      final MotionEvent.PointerProperties[] props =
          new MotionEvent.PointerProperties[getPointerCount(source)];
      int index = 0;
      for (int i = 0; i < pointers.size(); i++) {
        if (pointers.get(i).source == source) {
          final MotionEvent.PointerProperties p = new MotionEvent.PointerProperties();
          p.id = pointers.get(i).pointerId;
          switch (source) {
            case InputDevice.SOURCE_TOUCHSCREEN:
              p.toolType = MotionEvent.TOOL_TYPE_FINGER;
              break;
            case InputDevice.SOURCE_MOUSE:
              p.toolType = MotionEvent.TOOL_TYPE_MOUSE;
              break;
          }
          props[index++] = p;
        }
      }
      return props;
    }

    MotionEvent.PointerCoords[] getPointerCoords(final int source) {
      final MotionEvent.PointerCoords[] coords =
          new MotionEvent.PointerCoords[getPointerCount(source)];
      int index = 0;
      for (int i = 0; i < pointers.size(); i++) {
        if (pointers.get(i).source == source) {
          coords[index++] = pointers.get(i).getCoords();
        }
      }
      return coords;
    }
  }

  private void synthesizeNativePointer(
      final int source,
      final int pointerId,
      final int originalEventType,
      final int clientX,
      final int clientY,
      final double pressure,
      final int orientation,
      final int button) {
    if (mPointerState == null) {
      mPointerState = new SynthesizedEventState();
    }

    // Find the pointer if it already exists
    int pointerIndex = mPointerState.getPointerIndex(pointerId);

    // Event-specific handling
    int eventType = originalEventType;
    switch (originalEventType) {
      case MotionEvent.ACTION_POINTER_UP:
        if (pointerIndex < 0) {
          Log.w(LOGTAG, "Pointer-up for invalid pointer");
          return;
        }
        if (mPointerState.pointers.size() == 1) {
          // Last pointer is going up
          eventType = MotionEvent.ACTION_UP;
        }
        break;
      case MotionEvent.ACTION_CANCEL:
        if (pointerIndex < 0) {
          Log.w(LOGTAG, "Pointer-cancel for invalid pointer");
          return;
        }
        break;
      case MotionEvent.ACTION_POINTER_DOWN:
        if (pointerIndex < 0) {
          // Adding a new pointer
          pointerIndex = mPointerState.addPointer(pointerId, source);
          if (pointerIndex == 0) {
            // first pointer
            eventType = MotionEvent.ACTION_DOWN;
            mPointerState.downTime = SystemClock.uptimeMillis();
          }
        } else {
          // We're moving an existing pointer
          eventType = MotionEvent.ACTION_MOVE;
        }
        break;
      case MotionEvent.ACTION_HOVER_MOVE:
        if (pointerIndex < 0) {
          // Mouse-move a pointer without it going "down". However
          // in order to send the right MotionEvent without a lot of
          // duplicated code, we add the pointer to mPointerState,
          // and then remove it at the bottom of this function.
          pointerIndex = mPointerState.addPointer(pointerId, source);
        } else {
          // We're moving an existing mouse pointer that went down.
          eventType = MotionEvent.ACTION_MOVE;
        }
        break;
    }

    // Translate client origin to surface origin.
    mSession.getSurfaceBounds(mTempRect);
    final int surfaceX = clientX + mTempRect.left;
    final int surfaceY = clientY + mTempRect.top;

    // Update the pointer with the new info
    final PointerInfo info = mPointerState.pointers.get(pointerIndex);
    info.surfaceX = surfaceX;
    info.surfaceY = surfaceY;
    info.pressure = pressure;
    info.orientation = orientation;
    if (source == InputDevice.SOURCE_MOUSE) {
      if (eventType == MotionEvent.ACTION_DOWN || eventType == MotionEvent.ACTION_MOVE) {
        info.buttonState |= button;
      } else if (eventType == MotionEvent.ACTION_UP) {
        info.buttonState &= button;
      }
    }

    // Dispatch the event
    int action = 0;
    if (eventType == MotionEvent.ACTION_POINTER_DOWN
        || eventType == MotionEvent.ACTION_POINTER_UP) {
      // for pointer-down and pointer-up events we need to add the
      // index of the relevant pointer.
      action = (pointerIndex << MotionEvent.ACTION_POINTER_INDEX_SHIFT);
      action &= MotionEvent.ACTION_POINTER_INDEX_MASK;
    }
    action |= (eventType & MotionEvent.ACTION_MASK);
    final MotionEvent event =
        MotionEvent.obtain(
            /*downTime*/ mPointerState.downTime,
            /*eventTime*/ SystemClock.uptimeMillis(),
            /*action*/ action,
            /*pointerCount*/ mPointerState.getPointerCount(source),
            /*pointerProperties*/ mPointerState.getPointerProperties(source),
            /*pointerCoords*/ mPointerState.getPointerCoords(source),
            /*metaState*/ 0,
            /*buttonState*/ mPointerState.getPointerButtonState(source),
            /*xPrecision*/ 0,
            /*yPrecision*/ 0,
            /*deviceId*/ 0,
            /*edgeFlags*/ 0,
            /*source*/ source,
            /*flags*/ 0);

    mSynthesizedEvent = true;
    onTouchEvent(event);
    mSynthesizedEvent = false;

    // Forget about removed pointers
    if (eventType == MotionEvent.ACTION_POINTER_UP
        || eventType == MotionEvent.ACTION_UP
        || eventType == MotionEvent.ACTION_CANCEL
        || eventType == MotionEvent.ACTION_HOVER_MOVE) {
      mPointerState.pointers.remove(pointerIndex);
    }
  }

  /**
   * Scroll the document body by an offset from the current scroll position. Uses {@link
   * #SCROLL_BEHAVIOR_SMOOTH}.
   *
   * @param width {@link ScreenLength} offset to scroll along X axis.
   * @param height {@link ScreenLength} offset to scroll along Y axis.
   */
  @UiThread
  public void scrollBy(final @NonNull ScreenLength width, final @NonNull ScreenLength height) {
    scrollBy(width, height, SCROLL_BEHAVIOR_SMOOTH);
  }

  /**
   * Scroll the document body by an offset from the current scroll position.
   *
   * @param width {@link ScreenLength} offset to scroll along X axis.
   * @param height {@link ScreenLength} offset to scroll along Y axis.
   * @param behavior ScrollBehaviorType One of {@link #SCROLL_BEHAVIOR_SMOOTH}, {@link
   *     #SCROLL_BEHAVIOR_AUTO}, that specifies how to scroll the content.
   */
  @UiThread
  public void scrollBy(
      final @NonNull ScreenLength width,
      final @NonNull ScreenLength height,
      final @ScrollBehaviorType int behavior) {
    final GeckoBundle msg = buildScrollMessage(width, height, behavior);
    mSession.getEventDispatcher().dispatch("GeckoView:ScrollBy", msg);
  }

  /**
   * Scroll the document body to an absolute position. Uses {@link #SCROLL_BEHAVIOR_SMOOTH}.
   *
   * @param width {@link ScreenLength} position to scroll along X axis.
   * @param height {@link ScreenLength} position to scroll along Y axis.
   */
  @UiThread
  public void scrollTo(final @NonNull ScreenLength width, final @NonNull ScreenLength height) {
    scrollTo(width, height, SCROLL_BEHAVIOR_SMOOTH);
  }

  /**
   * Scroll the document body to an absolute position.
   *
   * @param width {@link ScreenLength} position to scroll along X axis.
   * @param height {@link ScreenLength} position to scroll along Y axis.
   * @param behavior ScrollBehaviorType One of {@link #SCROLL_BEHAVIOR_SMOOTH}, {@link
   *     #SCROLL_BEHAVIOR_AUTO}, that specifies how to scroll the content.
   */
  @UiThread
  public void scrollTo(
      final @NonNull ScreenLength width,
      final @NonNull ScreenLength height,
      final @ScrollBehaviorType int behavior) {
    final GeckoBundle msg = buildScrollMessage(width, height, behavior);
    mSession.getEventDispatcher().dispatch("GeckoView:ScrollTo", msg);
  }

  /** Scroll to the top left corner of the screen. Uses {@link #SCROLL_BEHAVIOR_SMOOTH}. */
  @UiThread
  public void scrollToTop() {
    scrollTo(ScreenLength.zero(), ScreenLength.top(), SCROLL_BEHAVIOR_SMOOTH);
  }

  /** Scroll to the bottom left corner of the screen. Uses {@link #SCROLL_BEHAVIOR_SMOOTH}. */
  @UiThread
  public void scrollToBottom() {
    scrollTo(ScreenLength.zero(), ScreenLength.bottom(), SCROLL_BEHAVIOR_SMOOTH);
  }

  private GeckoBundle buildScrollMessage(
      final @NonNull ScreenLength width,
      final @NonNull ScreenLength height,
      final @ScrollBehaviorType int behavior) {
    final GeckoBundle msg = new GeckoBundle();
    msg.putDouble("widthValue", width.getValue());
    msg.putInt("widthType", width.getType());
    msg.putDouble("heightValue", height.getValue());
    msg.putInt("heightType", height.getType());
    msg.putInt("behavior", behavior);
    return msg;
  }
}