1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.internal.widget;
18
19import android.app.Activity;
20import android.content.BroadcastReceiver;
21import android.content.Context;
22import android.content.Intent;
23import android.content.IntentFilter;
24import android.content.res.TypedArray;
25import android.util.AttributeSet;
26import android.util.Log;
27import android.view.MotionEvent;
28import android.view.VelocityTracker;
29import android.view.View;
30import android.view.ViewConfiguration;
31import android.view.ViewGroup;
32import android.view.ViewTreeObserver;
33import android.widget.FrameLayout;
34
35/**
36 * Special layout that finishes its activity when swiped away.
37 */
38public class SwipeDismissLayout extends FrameLayout {
39    private static final String TAG = "SwipeDismissLayout";
40
41    private static final float DISMISS_MIN_DRAG_WIDTH_RATIO = .33f;
42    private boolean mUseDynamicTranslucency = true;
43
44    public interface OnDismissedListener {
45        void onDismissed(SwipeDismissLayout layout);
46    }
47
48    public interface OnSwipeProgressChangedListener {
49        /**
50         * Called when the layout has been swiped and the position of the window should change.
51         *
52         * @param progress A number in [0, 1] representing how far to the
53         * right the window has been swiped
54         * @param translate A number in [0, w], where w is the width of the
55         * layout. This is equivalent to progress * layout.getWidth().
56         */
57        void onSwipeProgressChanged(SwipeDismissLayout layout, float progress, float translate);
58
59        void onSwipeCancelled(SwipeDismissLayout layout);
60    }
61
62    // Cached ViewConfiguration and system-wide constant values
63    private int mSlop;
64    private int mMinFlingVelocity;
65
66    // Transient properties
67    private int mActiveTouchId;
68    private float mDownX;
69    private float mDownY;
70    private boolean mSwiping;
71    private boolean mDismissed;
72    private boolean mDiscardIntercept;
73    private VelocityTracker mVelocityTracker;
74    private float mTranslationX;
75
76    private OnDismissedListener mDismissedListener;
77    private OnSwipeProgressChangedListener mProgressListener;
78    private ViewTreeObserver.OnEnterAnimationCompleteListener mOnEnterAnimationCompleteListener =
79            new ViewTreeObserver.OnEnterAnimationCompleteListener() {
80                @Override
81                public void onEnterAnimationComplete() {
82                    // SwipeDismissLayout assumes that the host Activity is translucent
83                    // and temporarily disables translucency when it is fully visible.
84                    // As soon as the user starts swiping, we will re-enable
85                    // translucency.
86                    if (mUseDynamicTranslucency && getContext() instanceof Activity) {
87                        ((Activity) getContext()).convertFromTranslucent();
88                    }
89                }
90            };
91    private BroadcastReceiver mScreenOffReceiver = new BroadcastReceiver() {
92        private Runnable mRunnable = new Runnable() {
93            @Override
94            public void run() {
95                if (mDismissed) {
96                    dismiss();
97                } else {
98                    cancel();
99                }
100                resetMembers();
101            }
102        };
103
104        @Override
105        public void onReceive(Context context, Intent intent) {
106            post(mRunnable);
107        }
108    };
109    private IntentFilter mScreenOffFilter = new IntentFilter(Intent.ACTION_SCREEN_OFF);
110
111    private float mLastX;
112
113    public SwipeDismissLayout(Context context) {
114        super(context);
115        init(context);
116    }
117
118    public SwipeDismissLayout(Context context, AttributeSet attrs) {
119        super(context, attrs);
120        init(context);
121    }
122
123    public SwipeDismissLayout(Context context, AttributeSet attrs, int defStyle) {
124        super(context, attrs, defStyle);
125        init(context);
126    }
127
128    private void init(Context context) {
129        ViewConfiguration vc = ViewConfiguration.get(context);
130        mSlop = vc.getScaledTouchSlop();
131        mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
132        TypedArray a = context.getTheme().obtainStyledAttributes(
133                com.android.internal.R.styleable.Theme);
134        mUseDynamicTranslucency = !a.hasValue(
135                com.android.internal.R.styleable.Window_windowIsTranslucent);
136        a.recycle();
137    }
138
139    public void setOnDismissedListener(OnDismissedListener listener) {
140        mDismissedListener = listener;
141    }
142
143    public void setOnSwipeProgressChangedListener(OnSwipeProgressChangedListener listener) {
144        mProgressListener = listener;
145    }
146
147    @Override
148    protected void onAttachedToWindow() {
149        super.onAttachedToWindow();
150        if (getContext() instanceof Activity) {
151            getViewTreeObserver().addOnEnterAnimationCompleteListener(
152                    mOnEnterAnimationCompleteListener);
153        }
154        getContext().registerReceiver(mScreenOffReceiver, mScreenOffFilter);
155    }
156
157    @Override
158    protected void onDetachedFromWindow() {
159        getContext().unregisterReceiver(mScreenOffReceiver);
160        if (getContext() instanceof Activity) {
161            getViewTreeObserver().removeOnEnterAnimationCompleteListener(
162                    mOnEnterAnimationCompleteListener);
163        }
164        super.onDetachedFromWindow();
165    }
166
167    @Override
168    public boolean onInterceptTouchEvent(MotionEvent ev) {
169        // offset because the view is translated during swipe
170        ev.offsetLocation(mTranslationX, 0);
171
172        switch (ev.getActionMasked()) {
173            case MotionEvent.ACTION_DOWN:
174                resetMembers();
175                mDownX = ev.getRawX();
176                mDownY = ev.getRawY();
177                mActiveTouchId = ev.getPointerId(0);
178                mVelocityTracker = VelocityTracker.obtain();
179                mVelocityTracker.addMovement(ev);
180                break;
181
182            case MotionEvent.ACTION_POINTER_DOWN:
183                int actionIndex = ev.getActionIndex();
184                mActiveTouchId = ev.getPointerId(actionIndex);
185                break;
186            case MotionEvent.ACTION_POINTER_UP:
187                actionIndex = ev.getActionIndex();
188                int pointerId = ev.getPointerId(actionIndex);
189                if (pointerId == mActiveTouchId) {
190                    // This was our active pointer going up. Choose a new active pointer.
191                    int newActionIndex = actionIndex == 0 ? 1 : 0;
192                    mActiveTouchId = ev.getPointerId(newActionIndex);
193                }
194                break;
195
196            case MotionEvent.ACTION_CANCEL:
197            case MotionEvent.ACTION_UP:
198                resetMembers();
199                break;
200
201            case MotionEvent.ACTION_MOVE:
202                if (mVelocityTracker == null || mDiscardIntercept) {
203                    break;
204                }
205
206                int pointerIndex = ev.findPointerIndex(mActiveTouchId);
207                if (pointerIndex == -1) {
208                    Log.e(TAG, "Invalid pointer index: ignoring.");
209                    mDiscardIntercept = true;
210                    break;
211                }
212                float dx = ev.getRawX() - mDownX;
213                float x = ev.getX(pointerIndex);
214                float y = ev.getY(pointerIndex);
215                if (dx != 0 && canScroll(this, false, dx, x, y)) {
216                    mDiscardIntercept = true;
217                    break;
218                }
219                updateSwiping(ev);
220                break;
221        }
222
223        return !mDiscardIntercept && mSwiping;
224    }
225
226    @Override
227    public boolean onTouchEvent(MotionEvent ev) {
228        if (mVelocityTracker == null) {
229            return super.onTouchEvent(ev);
230        }
231        // offset because the view is translated during swipe
232        ev.offsetLocation(mTranslationX, 0);
233        switch (ev.getActionMasked()) {
234            case MotionEvent.ACTION_UP:
235                updateDismiss(ev);
236                if (mDismissed) {
237                    dismiss();
238                } else if (mSwiping) {
239                    cancel();
240                }
241                resetMembers();
242                break;
243
244            case MotionEvent.ACTION_CANCEL:
245                cancel();
246                resetMembers();
247                break;
248
249            case MotionEvent.ACTION_MOVE:
250                mVelocityTracker.addMovement(ev);
251                mLastX = ev.getRawX();
252                updateSwiping(ev);
253                if (mSwiping) {
254                    if (mUseDynamicTranslucency && getContext() instanceof Activity) {
255                        ((Activity) getContext()).convertToTranslucent(null, null);
256                    }
257                    setProgress(ev.getRawX() - mDownX);
258                    break;
259                }
260        }
261        return true;
262    }
263
264    private void setProgress(float deltaX) {
265        mTranslationX = deltaX;
266        if (mProgressListener != null && deltaX >= 0)  {
267            mProgressListener.onSwipeProgressChanged(this, deltaX / getWidth(), deltaX);
268        }
269    }
270
271    private void dismiss() {
272        if (mDismissedListener != null) {
273            mDismissedListener.onDismissed(this);
274        }
275    }
276
277    protected void cancel() {
278        if (mUseDynamicTranslucency && getContext() instanceof Activity) {
279            ((Activity) getContext()).convertFromTranslucent();
280        }
281        if (mProgressListener != null) {
282            mProgressListener.onSwipeCancelled(this);
283        }
284    }
285
286    /**
287     * Resets internal members when canceling.
288     */
289    private void resetMembers() {
290        if (mVelocityTracker != null) {
291            mVelocityTracker.recycle();
292        }
293        mVelocityTracker = null;
294        mTranslationX = 0;
295        mDownX = 0;
296        mDownY = 0;
297        mSwiping = false;
298        mDismissed = false;
299        mDiscardIntercept = false;
300    }
301
302    private void updateSwiping(MotionEvent ev) {
303        if (!mSwiping) {
304            float deltaX = ev.getRawX() - mDownX;
305            float deltaY = ev.getRawY() - mDownY;
306            if ((deltaX * deltaX) + (deltaY * deltaY) > mSlop * mSlop) {
307                mSwiping = deltaX > mSlop * 2 && Math.abs(deltaY) < Math.abs(deltaX);
308            } else {
309                mSwiping = false;
310            }
311        }
312    }
313
314    private void updateDismiss(MotionEvent ev) {
315        float deltaX = ev.getRawX() - mDownX;
316        mVelocityTracker.addMovement(ev);
317        mVelocityTracker.computeCurrentVelocity(1000);
318        if (!mDismissed) {
319
320            if (deltaX > (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO) &&
321                    ev.getRawX() >= mLastX) {
322                mDismissed = true;
323            }
324        }
325        // Check if the user tried to undo this.
326        if (mDismissed && mSwiping) {
327            // Check if the user's finger is actually back
328            if (deltaX < (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO) ||
329                    // or user is flinging back left
330                    mVelocityTracker.getXVelocity() < -mMinFlingVelocity) {
331                mDismissed = false;
332            }
333        }
334    }
335
336    /**
337     * Tests scrollability within child views of v in the direction of dx.
338     *
339     * @param v View to test for horizontal scrollability
340     * @param checkV Whether the view v passed should itself be checked for scrollability (true),
341     *               or just its children (false).
342     * @param dx Delta scrolled in pixels. Only the sign of this is used.
343     * @param x X coordinate of the active touch point
344     * @param y Y coordinate of the active touch point
345     * @return true if child views of v can be scrolled by delta of dx.
346     */
347    protected boolean canScroll(View v, boolean checkV, float dx, float x, float y) {
348        if (v instanceof ViewGroup) {
349            final ViewGroup group = (ViewGroup) v;
350            final int scrollX = v.getScrollX();
351            final int scrollY = v.getScrollY();
352            final int count = group.getChildCount();
353            for (int i = count - 1; i >= 0; i--) {
354                final View child = group.getChildAt(i);
355                if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
356                        y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
357                        canScroll(child, true, dx, x + scrollX - child.getLeft(),
358                                y + scrollY - child.getTop())) {
359                    return true;
360                }
361            }
362        }
363
364        return checkV && v.canScrollHorizontally((int) -dx);
365    }
366}
367