/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.launcher3.touch;
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import static android.view.MotionEvent.INVALID_POINTER_ID;
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import android.content.Context;
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import android.graphics.PointF;
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import android.util.Log;
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import android.view.MotionEvent;
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import android.view.VelocityTracker;
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import android.view.ViewConfiguration;
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import com.android.launcher3.Utilities;
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import com.android.launcher3.testing.TestProtocol;
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import androidx.annotation.NonNull;
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import androidx.annotation.VisibleForTesting;
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/**
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* One dimensional scroll/drag/swipe gesture detector.
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*
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* Definition of swipe is different from android system in that this detector handles
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* 'swipe to dismiss', 'swiping up/down a container' but also keeps scrolling state before
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* swipe action happens
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*/
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public class SwipeDetector {
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private static final boolean DBG = false;
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private static final String TAG = "SwipeDetector";
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private int mScrollConditions;
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public static final int DIRECTION_POSITIVE = 1 << 0;
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public static final int DIRECTION_NEGATIVE = 1 << 1;
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public static final int DIRECTION_BOTH = DIRECTION_NEGATIVE | DIRECTION_POSITIVE;
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private static final float ANIMATION_DURATION = 1200;
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protected int mActivePointerId = INVALID_POINTER_ID;
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/**
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* The minimum release velocity in pixels per millisecond that triggers fling..
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*/
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public static final float RELEASE_VELOCITY_PX_MS = 1.0f;
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/* Scroll state, this is set to true during dragging and animation. */
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private ScrollState mState = ScrollState.IDLE;
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enum ScrollState {
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IDLE,
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DRAGGING, // onDragStart, onDrag
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SETTLING // onDragEnd
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}
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public static abstract class Direction {
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abstract float getDisplacement(MotionEvent ev, int pointerIndex, PointF refPoint,
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boolean isRtl);
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/**
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* Distance in pixels a touch can wander before we think the user is scrolling.
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*/
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abstract float getActiveTouchSlop(MotionEvent ev, int pointerIndex, PointF downPos);
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abstract float getVelocity(VelocityTracker tracker, boolean isRtl);
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abstract boolean isPositive(float displacement);
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abstract boolean isNegative(float displacement);
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}
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public static final Direction VERTICAL = new Direction() {
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@Override
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float getDisplacement(MotionEvent ev, int pointerIndex, PointF refPoint, boolean isRtl) {
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return ev.getY(pointerIndex) - refPoint.y;
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}
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@Override
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float getActiveTouchSlop(MotionEvent ev, int pointerIndex, PointF downPos) {
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return Math.abs(ev.getX(pointerIndex) - downPos.x);
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}
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@Override
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float getVelocity(VelocityTracker tracker, boolean isRtl) {
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return tracker.getYVelocity();
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}
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@Override
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boolean isPositive(float displacement) {
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// Up
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return displacement < 0;
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}
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@Override
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boolean isNegative(float displacement) {
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// Down
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return displacement > 0;
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}
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};
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public static final Direction HORIZONTAL = new Direction() {
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@Override
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float getDisplacement(MotionEvent ev, int pointerIndex, PointF refPoint, boolean isRtl) {
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float displacement = ev.getX(pointerIndex) - refPoint.x;
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if (isRtl) {
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displacement = -displacement;
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}
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return displacement;
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}
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@Override
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float getActiveTouchSlop(MotionEvent ev, int pointerIndex, PointF downPos) {
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return Math.abs(ev.getY(pointerIndex) - downPos.y);
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}
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@Override
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float getVelocity(VelocityTracker tracker, boolean isRtl) {
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float velocity = tracker.getXVelocity();
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if (isRtl) {
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velocity = -velocity;
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}
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return velocity;
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}
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@Override
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boolean isPositive(float displacement) {
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// Right
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return displacement > 0;
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}
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@Override
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boolean isNegative(float displacement) {
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// Left
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return displacement < 0;
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}
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};
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//------------------- ScrollState transition diagram -----------------------------------
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//
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// IDLE -> (mDisplacement > mTouchSlop) -> DRAGGING
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// DRAGGING -> (MotionEvent#ACTION_UP, MotionEvent#ACTION_CANCEL) -> SETTLING
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// SETTLING -> (MotionEvent#ACTION_DOWN) -> DRAGGING
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// SETTLING -> (View settled) -> IDLE
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private void setState(ScrollState newState) {
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if (TestProtocol.sDebugTracing) {
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Log.d(TestProtocol.NO_ALLAPPS_EVENT_TAG, "setState -- start: " + newState);
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}
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if (DBG) {
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Log.d(TAG, "setState:" + mState + "->" + newState);
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}
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// onDragStart and onDragEnd is reported ONLY on state transition
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if (newState == ScrollState.DRAGGING) {
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initializeDragging();
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if (mState == ScrollState.IDLE) {
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if (TestProtocol.sDebugTracing) {
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Log.d(TestProtocol.NO_ALLAPPS_EVENT_TAG, "setState -- 1: " + newState);
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}
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reportDragStart(false /* recatch */);
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} else if (mState == ScrollState.SETTLING) {
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reportDragStart(true /* recatch */);
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}
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}
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if (newState == ScrollState.SETTLING) {
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reportDragEnd();
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}
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mState = newState;
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if (com.android.launcher3.testing.TestProtocol.sDebugTracing) {
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android.util.Log.e(TestProtocol.NO_ALLAPPS_EVENT_TAG,
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"setState: " + newState + " @ " + android.util.Log.getStackTraceString(
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new Throwable()));
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}
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}
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public boolean isDraggingOrSettling() {
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return mState == ScrollState.DRAGGING || mState == ScrollState.SETTLING;
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}
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public int getDownX() {
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return (int) mDownPos.x;
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}
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public int getDownY() {
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return (int) mDownPos.y;
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}
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/**
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* There's no touch and there's no animation.
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*/
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public boolean isIdleState() {
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return mState == ScrollState.IDLE;
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}
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public boolean isSettlingState() {
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return mState == ScrollState.SETTLING;
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}
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public boolean isDraggingState() {
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return mState == ScrollState.DRAGGING;
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}
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private final PointF mDownPos = new PointF();
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private final PointF mLastPos = new PointF();
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private final Direction mDir;
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private final boolean mIsRtl;
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private final float mTouchSlop;
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private final float mMaxVelocity;
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/* Client of this gesture detector can register a callback. */
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private final Listener mListener;
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private VelocityTracker mVelocityTracker;
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private float mLastDisplacement;
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private float mDisplacement;
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private float mSubtractDisplacement;
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private boolean mIgnoreSlopWhenSettling;
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public interface Listener {
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void onDragStart(boolean start);
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boolean onDrag(float displacement);
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default boolean onDrag(float displacement, MotionEvent event) {
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return onDrag(displacement);
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}
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void onDragEnd(float velocity, boolean fling);
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}
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public SwipeDetector(@NonNull Context context, @NonNull Listener l, @NonNull Direction dir) {
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this(ViewConfiguration.get(context), l, dir, Utilities.isRtl(context.getResources()));
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}
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@VisibleForTesting
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protected SwipeDetector(@NonNull ViewConfiguration config, @NonNull Listener l,
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@NonNull Direction dir, boolean isRtl) {
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mListener = l;
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mDir = dir;
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mIsRtl = isRtl;
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mTouchSlop = config.getScaledTouchSlop();
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mMaxVelocity = config.getScaledMaximumFlingVelocity();
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}
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public void setDetectableScrollConditions(int scrollDirectionFlags, boolean ignoreSlop) {
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mScrollConditions = scrollDirectionFlags;
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mIgnoreSlopWhenSettling = ignoreSlop;
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}
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public int getScrollDirections() {
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return mScrollConditions;
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}
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private boolean shouldScrollStart(MotionEvent ev, int pointerIndex) {
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// reject cases where the angle or slop condition is not met.
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if (Math.max(mDir.getActiveTouchSlop(ev, pointerIndex, mDownPos), mTouchSlop)
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> Math.abs(mDisplacement)) {
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return false;
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}
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// Check if the client is interested in scroll in current direction.
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if (((mScrollConditions & DIRECTION_NEGATIVE) > 0 && mDir.isNegative(mDisplacement)) ||
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((mScrollConditions & DIRECTION_POSITIVE) > 0 && mDir.isPositive(mDisplacement))) {
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return true;
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}
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return false;
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}
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public boolean onTouchEvent(MotionEvent ev) {
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int actionMasked = ev.getActionMasked();
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if (actionMasked == MotionEvent.ACTION_DOWN && mVelocityTracker != null) {
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mVelocityTracker.clear();
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}
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if (mVelocityTracker == null) {
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mVelocityTracker = VelocityTracker.obtain();
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}
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mVelocityTracker.addMovement(ev);
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switch (actionMasked) {
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case MotionEvent.ACTION_DOWN:
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mActivePointerId = ev.getPointerId(0);
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mDownPos.set(ev.getX(), ev.getY());
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mLastPos.set(mDownPos);
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mLastDisplacement = 0;
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mDisplacement = 0;
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if (mState == ScrollState.SETTLING && mIgnoreSlopWhenSettling) {
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setState(ScrollState.DRAGGING);
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}
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break;
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//case MotionEvent.ACTION_POINTER_DOWN:
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case MotionEvent.ACTION_POINTER_UP:
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int ptrIdx = ev.getActionIndex();
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int ptrId = ev.getPointerId(ptrIdx);
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if (ptrId == mActivePointerId) {
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final int newPointerIdx = ptrIdx == 0 ? 1 : 0;
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mDownPos.set(
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ev.getX(newPointerIdx) - (mLastPos.x - mDownPos.x),
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ev.getY(newPointerIdx) - (mLastPos.y - mDownPos.y));
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mLastPos.set(ev.getX(newPointerIdx), ev.getY(newPointerIdx));
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mActivePointerId = ev.getPointerId(newPointerIdx);
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}
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break;
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case MotionEvent.ACTION_MOVE:
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int pointerIndex = ev.findPointerIndex(mActivePointerId);
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if (pointerIndex == INVALID_POINTER_ID) {
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break;
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}
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mDisplacement = mDir.getDisplacement(ev, pointerIndex, mDownPos, mIsRtl);
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if (TestProtocol.sDebugTracing) {
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Log.d(TestProtocol.NO_ALLAPPS_EVENT_TAG, "onTouchEvent 1");
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}
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// handle state and listener calls.
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if (mState != ScrollState.DRAGGING && shouldScrollStart(ev, pointerIndex)) {
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if (TestProtocol.sDebugTracing) {
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Log.d(TestProtocol.NO_ALLAPPS_EVENT_TAG, "onTouchEvent 2");
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}
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setState(ScrollState.DRAGGING);
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}
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if (mState == ScrollState.DRAGGING) {
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reportDragging(ev);
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}
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mLastPos.set(ev.getX(pointerIndex), ev.getY(pointerIndex));
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break;
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case MotionEvent.ACTION_CANCEL:
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case MotionEvent.ACTION_UP:
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// These are synthetic events and there is no need to update internal values.
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if (mState == ScrollState.DRAGGING) {
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setState(ScrollState.SETTLING);
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}
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mVelocityTracker.recycle();
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mVelocityTracker = null;
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break;
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default:
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break;
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}
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return true;
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}
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public void finishedScrolling() {
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setState(ScrollState.IDLE);
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}
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private boolean reportDragStart(boolean recatch) {
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mListener.onDragStart(!recatch);
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if (DBG) {
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Log.d(TAG, "onDragStart recatch:" + recatch);
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}
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return true;
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}
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private void initializeDragging() {
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if (mState == ScrollState.SETTLING && mIgnoreSlopWhenSettling) {
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mSubtractDisplacement = 0;
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}
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if (mDisplacement > 0) {
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mSubtractDisplacement = mTouchSlop;
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} else {
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mSubtractDisplacement = -mTouchSlop;
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}
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}
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/**
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* Returns if the start drag was towards the positive direction or negative.
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*
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* @see #setDetectableScrollConditions(int, boolean)
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* @see #DIRECTION_BOTH
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*/
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public boolean wasInitialTouchPositive() {
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return mDir.isPositive(mSubtractDisplacement);
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}
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private boolean reportDragging(MotionEvent event) {
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if (mDisplacement != mLastDisplacement) {
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if (DBG) {
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Log.d(TAG, String.format("onDrag disp=%.1f", mDisplacement));
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}
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mLastDisplacement = mDisplacement;
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return mListener.onDrag(mDisplacement - mSubtractDisplacement, event);
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}
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return true;
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}
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private void reportDragEnd() {
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mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity);
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float velocity = mDir.getVelocity(mVelocityTracker, mIsRtl) / 1000;
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if (DBG) {
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Log.d(TAG, String.format("onScrollEnd disp=%.1f, velocity=%.1f",
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mDisplacement, velocity));
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}
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mListener.onDragEnd(velocity, Math.abs(velocity) > RELEASE_VELOCITY_PX_MS);
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}
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public static long calculateDuration(float velocity, float progressNeeded) {
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// TODO: make these values constants after tuning.
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float velocityDivisor = Math.max(2f, Math.abs(0.5f * velocity));
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float travelDistance = Math.max(0.2f, progressNeeded);
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long duration = (long) Math.max(100, ANIMATION_DURATION / velocityDivisor * travelDistance);
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if (DBG) {
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Log.d(TAG, String.format("calculateDuration=%d, v=%f, d=%f", duration, velocity, progressNeeded));
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}
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return duration;
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}
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}
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