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        @Override
93        public void onReceive(Context context, Intent intent) {
94            if (mDismissed) {
95                dismiss();
96            } else {
97                cancel();
98            }
99            resetMembers();
100        }
101    };
102    private IntentFilter mScreenOffFilter = new IntentFilter(Intent.ACTION_SCREEN_OFF);
103
104    private float mLastX;
105
106    public SwipeDismissLayout(Context context) {
107        super(context);
108        init(context);
109    }
110
111    public SwipeDismissLayout(Context context, AttributeSet attrs) {
112        super(context, attrs);
113        init(context);
114    }
115
116    public SwipeDismissLayout(Context context, AttributeSet attrs, int defStyle) {
117        super(context, attrs, defStyle);
118        init(context);
119    }
120
121    private void init(Context context) {
122        ViewConfiguration vc = ViewConfiguration.get(context);
123        mSlop = vc.getScaledTouchSlop();
124        mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
125        TypedArray a = context.getTheme().obtainStyledAttributes(
126                com.android.internal.R.styleable.Theme);
127        mUseDynamicTranslucency = !a.hasValue(
128                com.android.internal.R.styleable.Window_windowIsTranslucent);
129        a.recycle();
130    }
131
132    public void setOnDismissedListener(OnDismissedListener listener) {
133        mDismissedListener = listener;
134    }
135
136    public void setOnSwipeProgressChangedListener(OnSwipeProgressChangedListener listener) {
137        mProgressListener = listener;
138    }
139
140    @Override
141    protected void onAttachedToWindow() {
142        super.onAttachedToWindow();
143        if (getContext() instanceof Activity) {
144            getViewTreeObserver().addOnEnterAnimationCompleteListener(
145                    mOnEnterAnimationCompleteListener);
146        }
147        getContext().registerReceiver(mScreenOffReceiver, mScreenOffFilter);
148    }
149
150    @Override
151    protected void onDetachedFromWindow() {
152        getContext().unregisterReceiver(mScreenOffReceiver);
153        if (getContext() instanceof Activity) {
154            getViewTreeObserver().removeOnEnterAnimationCompleteListener(
155                    mOnEnterAnimationCompleteListener);
156        }
157        super.onDetachedFromWindow();
158    }
159
160    @Override
161    public boolean onInterceptTouchEvent(MotionEvent ev) {
162        // offset because the view is translated during swipe
163        ev.offsetLocation(mTranslationX, 0);
164
165        switch (ev.getActionMasked()) {
166            case MotionEvent.ACTION_DOWN:
167                resetMembers();
168                mDownX = ev.getRawX();
169                mDownY = ev.getRawY();
170                mActiveTouchId = ev.getPointerId(0);
171                mVelocityTracker = VelocityTracker.obtain();
172                mVelocityTracker.addMovement(ev);
173                break;
174
175            case MotionEvent.ACTION_POINTER_DOWN:
176                int actionIndex = ev.getActionIndex();
177                mActiveTouchId = ev.getPointerId(actionIndex);
178                break;
179            case MotionEvent.ACTION_POINTER_UP:
180                actionIndex = ev.getActionIndex();
181                int pointerId = ev.getPointerId(actionIndex);
182                if (pointerId == mActiveTouchId) {
183                    // This was our active pointer going up. Choose a new active pointer.
184                    int newActionIndex = actionIndex == 0 ? 1 : 0;
185                    mActiveTouchId = ev.getPointerId(newActionIndex);
186                }
187                break;
188
189            case MotionEvent.ACTION_CANCEL:
190            case MotionEvent.ACTION_UP:
191                resetMembers();
192                break;
193
194            case MotionEvent.ACTION_MOVE:
195                if (mVelocityTracker == null || mDiscardIntercept) {
196                    break;
197                }
198
199                int pointerIndex = ev.findPointerIndex(mActiveTouchId);
200                if (pointerIndex == -1) {
201                    Log.e(TAG, "Invalid pointer index: ignoring.");
202                    mDiscardIntercept = true;
203                    break;
204                }
205                float dx = ev.getRawX() - mDownX;
206                float x = ev.getX(pointerIndex);
207                float y = ev.getY(pointerIndex);
208                if (dx != 0 && canScroll(this, false, dx, x, y)) {
209                    mDiscardIntercept = true;
210                    break;
211                }
212                updateSwiping(ev);
213                break;
214        }
215
216        return !mDiscardIntercept && mSwiping;
217    }
218
219    @Override
220    public boolean onTouchEvent(MotionEvent ev) {
221        if (mVelocityTracker == null) {
222            return super.onTouchEvent(ev);
223        }
224        // offset because the view is translated during swipe
225        ev.offsetLocation(mTranslationX, 0);
226        switch (ev.getActionMasked()) {
227            case MotionEvent.ACTION_UP:
228                updateDismiss(ev);
229                if (mDismissed) {
230                    dismiss();
231                } else if (mSwiping) {
232                    cancel();
233                }
234                resetMembers();
235                break;
236
237            case MotionEvent.ACTION_CANCEL:
238                cancel();
239                resetMembers();
240                break;
241
242            case MotionEvent.ACTION_MOVE:
243                mVelocityTracker.addMovement(ev);
244                mLastX = ev.getRawX();
245                updateSwiping(ev);
246                if (mSwiping) {
247                    if (mUseDynamicTranslucency && getContext() instanceof Activity) {
248                        ((Activity) getContext()).convertToTranslucent(null, null);
249                    }
250                    setProgress(ev.getRawX() - mDownX);
251                    break;
252                }
253        }
254        return true;
255    }
256
257    private void setProgress(float deltaX) {
258        mTranslationX = deltaX;
259        if (mProgressListener != null && deltaX >= 0)  {
260            mProgressListener.onSwipeProgressChanged(this, deltaX / getWidth(), deltaX);
261        }
262    }
263
264    private void dismiss() {
265        if (mDismissedListener != null) {
266            mDismissedListener.onDismissed(this);
267        }
268    }
269
270    protected void cancel() {
271        if (mUseDynamicTranslucency && getContext() instanceof Activity) {
272            ((Activity) getContext()).convertFromTranslucent();
273        }
274        if (mProgressListener != null) {
275            mProgressListener.onSwipeCancelled(this);
276        }
277    }
278
279    /**
280     * Resets internal members when canceling.
281     */
282    private void resetMembers() {
283        if (mVelocityTracker != null) {
284            mVelocityTracker.recycle();
285        }
286        mVelocityTracker = null;
287        mTranslationX = 0;
288        mDownX = 0;
289        mDownY = 0;
290        mSwiping = false;
291        mDismissed = false;
292        mDiscardIntercept = false;
293    }
294
295    private void updateSwiping(MotionEvent ev) {
296        if (!mSwiping) {
297            float deltaX = ev.getRawX() - mDownX;
298            float deltaY = ev.getRawY() - mDownY;
299            if ((deltaX * deltaX) + (deltaY * deltaY) > mSlop * mSlop) {
300                mSwiping = deltaX > mSlop * 2 && Math.abs(deltaY) < Math.abs(deltaX);
301            } else {
302                mSwiping = false;
303            }
304        }
305    }
306
307    private void updateDismiss(MotionEvent ev) {
308        float deltaX = ev.getRawX() - mDownX;
309        mVelocityTracker.addMovement(ev);
310        mVelocityTracker.computeCurrentVelocity(1000);
311        if (!mDismissed) {
312
313            if (deltaX > (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO) &&
314                    ev.getRawX() >= mLastX) {
315                mDismissed = true;
316            }
317        }
318        // Check if the user tried to undo this.
319        if (mDismissed && mSwiping) {
320            // Check if the user's finger is actually back
321            if (deltaX < (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO) ||
322                    // or user is flinging back left
323                    mVelocityTracker.getXVelocity() < -mMinFlingVelocity) {
324                mDismissed = false;
325            }
326        }
327    }
328
329    /**
330     * Tests scrollability within child views of v in the direction of dx.
331     *
332     * @param v View to test for horizontal scrollability
333     * @param checkV Whether the view v passed should itself be checked for scrollability (true),
334     *               or just its children (false).
335     * @param dx Delta scrolled in pixels. Only the sign of this is used.
336     * @param x X coordinate of the active touch point
337     * @param y Y coordinate of the active touch point
338     * @return true if child views of v can be scrolled by delta of dx.
339     */
340    protected boolean canScroll(View v, boolean checkV, float dx, float x, float y) {
341        if (v instanceof ViewGroup) {
342            final ViewGroup group = (ViewGroup) v;
343            final int scrollX = v.getScrollX();
344            final int scrollY = v.getScrollY();
345            final int count = group.getChildCount();
346            for (int i = count - 1; i >= 0; i--) {
347                final View child = group.getChildAt(i);
348                if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
349                        y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
350                        canScroll(child, true, dx, x + scrollX - child.getLeft(),
351                                y + scrollY - child.getTop())) {
352                    return true;
353                }
354            }
355        }
356
357        return checkV && v.canScrollHorizontally((int) -dx);
358    }
359}
360