| /* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ using System; using Android.Runtime; using Android.Content; using Android.Util; using Android.Views; namespace FriendTab { public class DoubleSwipeDetector { public interface IOnScaleGestureListener { bool OnScale(DoubleSwipeDetector detector); bool OnScaleBegin(DoubleSwipeDetector detector); void OnScaleEnd(DoubleSwipeDetector detector); } public class SimpleOnScaleGestureListener : IOnScaleGestureListener { public bool OnScale(DoubleSwipeDetector detector) { return false; } public bool OnScaleBegin(DoubleSwipeDetector detector) { return true; } public void OnScaleEnd(DoubleSwipeDetector detector) { // Intentionally empty } } private static float PRESSURE_THRESHOLD = 0.67f; private Context mContext; private IOnScaleGestureListener mListener; private bool mGestureInProgress; private MotionEvent mPrevEvent; private MotionEvent mCurrEvent; private float mFocusX; private float mFocusY; private float mPrevFingerDiffX; private float mPrevFingerDiffY; private float mCurrFingerDiffX; private float mCurrFingerDiffY; private float mCurrLen; private float mPrevLen; private float mScaleFactor; private float mCurrPressure; private float mPrevPressure; private long mTimeDelta; private bool mInvalidGesture; // Pointer IDs currently responsible for the two fingers controlling the gesture private int mActiveId0; private int mActiveId1; private bool mActive0MostRecent; public DoubleSwipeDetector (Context context, IOnScaleGestureListener listener) { mContext = context; mListener = listener; } public bool OnTouchEvent (MotionEvent evt) { var action = evt.ActionMasked; if (action == MotionEventActions.Down) { reset(); // Start fresh } bool handled = true; if (mInvalidGesture) { handled = false; } else if (!mGestureInProgress) { switch (action) { case MotionEventActions.Down: { mActiveId0 = evt.GetPointerId(0); mActive0MostRecent = true; } break; case MotionEventActions.Up: reset(); break; case MotionEventActions.PointerDown: { // We have a new multi-finger gesture if (mPrevEvent != null) mPrevEvent.Recycle(); mPrevEvent = MotionEvent.Obtain(evt); mTimeDelta = 0; int index1 = evt.ActionIndex; int index0 = evt.FindPointerIndex(mActiveId0); mActiveId1 = evt.GetPointerId(index1); if (index0 < 0 || index0 == index1) { // Probably someone sending us a broken evt stream. index0 = findNewActiveIndex(evt, mActiveId1, -1); mActiveId0 = evt.GetPointerId(index0); } mActive0MostRecent = false; setContext(evt); mGestureInProgress = mListener.OnScaleBegin(this); break; } } } else { // Transform gesture in progress - attempt to handle it switch (action) { case MotionEventActions.Down: { // End the old gesture and begin a new one with the most recent two fingers. mListener.OnScaleEnd(this); int oldActive0 = mActiveId0; int oldActive1 = mActiveId1; reset(); mPrevEvent = MotionEvent.Obtain(evt); mActiveId0 = mActive0MostRecent ? oldActive0 : oldActive1; mActiveId1 = evt.GetPointerId(evt.ActionIndex); mActive0MostRecent = false; int index0 = evt.FindPointerIndex (mActiveId0); if (index0 < 0 || mActiveId0 == mActiveId1) { index0 = findNewActiveIndex(evt, mActiveId1, -1); mActiveId0 = evt.GetPointerId(index0); } setContext(evt); mGestureInProgress = mListener.OnScaleBegin(this); } break; case MotionEventActions.PointerUp: { int pointerCount = evt.PointerCount; int actionIndex = evt.ActionIndex; int actionId = evt.GetPointerId(actionIndex); bool gestureEnded = false; if (pointerCount > 2) { if (actionId == mActiveId0) { int newIndex = findNewActiveIndex(evt, mActiveId1, actionIndex); if (newIndex >= 0) { mListener.OnScaleEnd(this); mActiveId0 = evt.GetPointerId(newIndex); mActive0MostRecent = true; mPrevEvent = MotionEvent.Obtain(evt); setContext(evt); mGestureInProgress = mListener.OnScaleBegin(this); } else { gestureEnded = true; } } else if (actionId == mActiveId1) { int newIndex = findNewActiveIndex(evt, mActiveId0, actionIndex); if (newIndex >= 0) { mListener.OnScaleEnd(this); mActiveId1 = evt.GetPointerId(newIndex); mActive0MostRecent = false; mPrevEvent = MotionEvent.Obtain(evt); setContext(evt); mGestureInProgress = mListener.OnScaleBegin(this); } else { gestureEnded = true; } } mPrevEvent.Recycle(); mPrevEvent = MotionEvent.Obtain(evt); setContext(evt); } else { gestureEnded = true; } if (gestureEnded) { // Gesture ended setContext(evt); // Set focus point to the remaining finger int activeId = actionId == mActiveId0 ? mActiveId1 : mActiveId0; int index = evt.FindPointerIndex(activeId); mFocusX = evt.GetX(index); mFocusY = evt.GetY(index); mListener.OnScaleEnd(this); reset(); mActiveId0 = activeId; mActive0MostRecent = true; } } break; case MotionEventActions.Cancel: mListener.OnScaleEnd(this); reset(); break; case MotionEventActions.Up: reset(); break; case MotionEventActions.Move: { setContext(evt); // Only accept the evt if our relative pressure is within // a certain limit - this can help filter shaky data as a // finger is lifted. if (mCurrPressure / mPrevPressure > PRESSURE_THRESHOLD) { bool updatePrevious = mListener.OnScale(this); if (updatePrevious) { mPrevEvent.Recycle(); mPrevEvent = MotionEvent.Obtain(evt); } } } break; } } return handled; } private int findNewActiveIndex(MotionEvent ev, int otherActiveId, int removedPointerIndex) { int pointerCount = ev.PointerCount; // It's ok if this isn't found and returns -1, it simply won't match. int otherActiveIndex = ev.FindPointerIndex(otherActiveId); // Pick a new id and update tracking state. for (int i = 0; i < pointerCount; i++) { if (i != removedPointerIndex && i != otherActiveIndex) { return i; } } return -1; } private void setContext(MotionEvent curr) { if (mCurrEvent != null) { mCurrEvent.Recycle(); } mCurrEvent = MotionEvent.Obtain(curr); mCurrLen = -1; mPrevLen = -1; mScaleFactor = -1; MotionEvent prev = mPrevEvent; int prevIndex0 = prev.FindPointerIndex(mActiveId0); int prevIndex1 = prev.FindPointerIndex(mActiveId1); int currIndex0 = curr.FindPointerIndex(mActiveId0); int currIndex1 = curr.FindPointerIndex(mActiveId1); if (prevIndex0 < 0 || prevIndex1 < 0 || currIndex0 < 0 || currIndex1 < 0) { mInvalidGesture = true; if (mGestureInProgress) { mListener.OnScaleEnd(this); } return; } float px0 = prev.GetX(prevIndex0); float py0 = prev.GetY(prevIndex0); float px1 = prev.GetX(prevIndex1); float py1 = prev.GetY(prevIndex1); float cx0 = curr.GetX(currIndex0); float cy0 = curr.GetY(currIndex0); float cx1 = curr.GetX(currIndex1); float cy1 = curr.GetY(currIndex1); float pvx = px1 - px0; float pvy = py1 - py0; float cvx = cx1 - cx0; float cvy = cy1 - cy0; mPrevFingerDiffX = pvx; mPrevFingerDiffY = pvy; mCurrFingerDiffX = cvx; mCurrFingerDiffY = cvy; mFocusX = cx0 + cvx * 0.5f; mFocusY = cy0 + cvy * 0.5f; mTimeDelta = curr.EventTime - prev.EventTime; mCurrPressure = curr.GetPressure(currIndex0) + curr.GetPressure(currIndex1); mPrevPressure = prev.GetPressure(prevIndex0) + prev.GetPressure(prevIndex1); } private void reset() { if (mPrevEvent != null) { mPrevEvent.Recycle(); mPrevEvent = null; } if (mCurrEvent != null) { mCurrEvent.Recycle(); mCurrEvent = null; } mGestureInProgress = false; mActiveId0 = -1; mActiveId1 = -1; mInvalidGesture = false; } public bool IsInProgress { get { return mGestureInProgress; } } public float FocusX { get { return mFocusX; } } public float FocusY { get { return mFocusY; } } public float CurrentSpan { get { if (mCurrLen == -1) { float cvx = mCurrFingerDiffX; float cvy = mCurrFingerDiffY; mCurrLen = (float)Math.Sqrt (cvx * cvx + cvy * cvy); } return mCurrLen; } } public float CurrentSpanX { get { return mCurrFingerDiffX; } } public float CurrentSpanY { get { return mCurrFingerDiffY; } } public float PreviousSpan { get { if (mPrevLen == -1) { float pvx = mPrevFingerDiffX; float pvy = mPrevFingerDiffY; mPrevLen = (float)Math.Sqrt (pvx * pvx + pvy * pvy); } return mPrevLen; } } public float PreviousSpanX { get { return mPrevFingerDiffX; } } public float PreviousSpanY { get { return mPrevFingerDiffY; } } public float ScaleFactor { get { if (mScaleFactor == -1) { mScaleFactor = CurrentSpan / PreviousSpan; } return mScaleFactor; } } public long TimeDelta { get { return mTimeDelta; } } public long EventTime { get { return mCurrEvent.EventTime; } } } } | 
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