多点触控（图片旋转与缩放

package com.almeros.android.multitouch; import android.content.Context; import android.view.MotionEvent; /** * @author Robert Nordan (robert.nordan@norkart.no) * * Copyright (c) 2013, Norkart AS * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY * OF SUCH DAMAGE. */ public class ShoveGestureDetector extends TwoFingerGestureDetector { /** * Listener which must be implemented which is used by ShoveGestureDetector * to perform callbacks to any implementing class which is registered to a * ShoveGestureDetector via the constructor. * * @see ShoveGestureDetector.SimpleOnShoveGestureListener */ public interface OnShoveGestureListener { public boolean onShove(ShoveGestureDetector detector); public boolean onShoveBegin(ShoveGestureDetector detector); public void onShoveEnd(ShoveGestureDetector detector); } /** * Helper class which may be extended and where the methods may be * implemented. This way it is not necessary to implement all methods * of OnShoveGestureListener. */ public static class SimpleOnShoveGestureListener implements OnShoveGestureListener { public boolean onShove(ShoveGestureDetector detector) { return false; } public boolean onShoveBegin(ShoveGestureDetector detector) { return true; } public void onShoveEnd(ShoveGestureDetector detector) { // Do nothing, overridden implementation may be used } } private float mPrevAverageY; private float mCurrAverageY; private final OnShoveGestureListener mListener; private boolean mSloppyGesture; public ShoveGestureDetector(Context context, OnShoveGestureListener listener) { super(context); mListener = listener; } @Override protected void handleStartProgressEvent(int actionCode, MotionEvent event){ switch (actionCode) { case MotionEvent.ACTION_POINTER_DOWN: // At least the second finger is on screen now resetState(); // In case we missed an UP/CANCEL event mPrevEvent = MotionEvent.obtain(event); mTimeDelta = 0; updateStateByEvent(event); // See if we have a sloppy gesture mSloppyGesture = isSloppyGesture(event); if(!mSloppyGesture){ // No, start gesture now mGestureInProgress = mListener.onShoveBegin(this); } break; case MotionEvent.ACTION_MOVE: if (!mSloppyGesture) { break; } // See if we still have a sloppy gesture mSloppyGesture = isSloppyGesture(event); if(!mSloppyGesture){ // No, start normal gesture now mGestureInProgress = mListener.onShoveBegin(this); } break; case MotionEvent.ACTION_POINTER_UP: if (!mSloppyGesture) { break; } break; } } @Override protected void handleInProgressEvent(int actionCode, MotionEvent event){ switch (actionCode) { case MotionEvent.ACTION_POINTER_UP: // Gesture ended but updateStateByEvent(event); if (!mSloppyGesture) { mListener.onShoveEnd(this); } resetState(); break; case MotionEvent.ACTION_CANCEL: if (!mSloppyGesture) { mListener.onShoveEnd(this); } resetState(); break; case MotionEvent.ACTION_MOVE: updateStateByEvent(event); // Only accept the event if our relative pressure is within // a certain limit. This can help filter shaky data as a // finger is lifted. Also check that shove is meaningful. if (mCurrPressure / mPrevPressure > PRESSURE_THRESHOLD && Math.abs(getShovePixelsDelta()) > 0.5f) { final boolean updatePrevious = mListener.onShove(this); if (updatePrevious) { mPrevEvent.recycle(); mPrevEvent = MotionEvent.obtain(event); } } break; } } @Override protected void resetState() { super.resetState(); mSloppyGesture = false; mPrevAverageY = 0.0f; mCurrAverageY = 0.0f; } @Override protected void updateStateByEvent(MotionEvent curr){ super.updateStateByEvent(curr); final MotionEvent prev = mPrevEvent; float py0 = prev.getY(0); float py1 = prev.getY(1); mPrevAverageY = (py0 + py1) / 2.0f; float cy0 = curr.getY(0); float cy1 = curr.getY(1); mCurrAverageY = (cy0 + cy1) / 2.0f; } @Override protected boolean isSloppyGesture(MotionEvent event){ boolean sloppy = super.isSloppyGesture(event); if (sloppy) return true; // If it's not traditionally sloppy, we check if the angle between fingers // is acceptable. double angle = Math.abs(Math.atan2(mCurrFingerDiffY, mCurrFingerDiffX)); //about 20 degrees, left or right return !(( 0.0f < angle && angle < 0.35f) || 2.79f < angle && angle < Math.PI); } /** * Return the distance in pixels from the previous shove event to the current * event. * * @return The current distance in pixels. */ public float getShovePixelsDelta() { return mCurrAverageY - mPrevAverageY; } }