SwipeDismissLayout.java revision 23958c6e2ffd4e76a88bc553fe2874d2f5f3f5e2 
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.animation.TimeInterpolator;
20import android.app.Activity;
21import android.content.Context;
22import android.content.res.TypedArray;
23import android.util.AttributeSet;
24import android.util.Log;
25import android.view.MotionEvent;
26import android.view.VelocityTracker;
27import android.view.View;
28import android.view.ViewConfiguration;
29import android.view.ViewGroup;
30import android.view.ViewTreeObserver;
31import android.view.animation.AccelerateInterpolator;
32import android.view.animation.DecelerateInterpolator;
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    private int mMaxFlingVelocity;
66    private long mAnimationTime;
67    private TimeInterpolator mCancelInterpolator;
68    private TimeInterpolator mDismissInterpolator;
69
70    // Transient properties
71    private int mActiveTouchId;
72    private float mDownX;
73    private float mDownY;
74    private boolean mSwiping;
75    private boolean mDismissed;
76    private boolean mDiscardIntercept;
77    private VelocityTracker mVelocityTracker;
78    private float mTranslationX;
79
80    private OnDismissedListener mDismissedListener;
81    private OnSwipeProgressChangedListener mProgressListener;
82    private ViewTreeObserver.OnEnterAnimationCompleteListener mOnEnterAnimationCompleteListener =
83            new ViewTreeObserver.OnEnterAnimationCompleteListener() {
84                @Override
85                public void onEnterAnimationComplete() {
86                    // SwipeDismissLayout assumes that the host Activity is translucent
87                    // and temporarily disables translucency when it is fully visible.
88                    // As soon as the user starts swiping, we will re-enable
89                    // translucency.
90                    if (mUseDynamicTranslucency && getContext() instanceof Activity) {
91                        ((Activity) getContext()).convertFromTranslucent();
92                    }
93                }
94            };
95
96    private float mLastX;
97
98    public SwipeDismissLayout(Context context) {
99        super(context);
100        init(context);
101    }
102
103    public SwipeDismissLayout(Context context, AttributeSet attrs) {
104        super(context, attrs);
105        init(context);
106    }
107
108    public SwipeDismissLayout(Context context, AttributeSet attrs, int defStyle) {
109        super(context, attrs, defStyle);
110        init(context);
111    }
112
113    private void init(Context context) {
114        ViewConfiguration vc = ViewConfiguration.get(getContext());
115        mSlop = vc.getScaledTouchSlop();
116        mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
117        mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
118        mAnimationTime = getContext().getResources().getInteger(
119                android.R.integer.config_shortAnimTime);
120        mCancelInterpolator = new DecelerateInterpolator(1.5f);
121        mDismissInterpolator = new AccelerateInterpolator(1.5f);
122        TypedArray a = context.getTheme().obtainStyledAttributes(
123                com.android.internal.R.styleable.Theme);
124        mUseDynamicTranslucency = !a.hasValue(
125                com.android.internal.R.styleable.Window_windowIsTranslucent);
126        a.recycle();
127    }
128
129    public void setOnDismissedListener(OnDismissedListener listener) {
130        mDismissedListener = listener;
131    }
132
133    public void setOnSwipeProgressChangedListener(OnSwipeProgressChangedListener listener) {
134        mProgressListener = listener;
135    }
136
137    @Override
138    protected void onAttachedToWindow() {
139        super.onAttachedToWindow();
140        if (getContext() instanceof Activity) {
141            getViewTreeObserver().addOnEnterAnimationCompleteListener(
142                    mOnEnterAnimationCompleteListener);
143        }
144    }
145
146    @Override
147    protected void onDetachedFromWindow() {
148        super.onDetachedFromWindow();
149        if (getContext() instanceof Activity) {
150            getViewTreeObserver().removeOnEnterAnimationCompleteListener(
151                    mOnEnterAnimationCompleteListener);
152        }
153    }
154
155    @Override
156    public boolean onInterceptTouchEvent(MotionEvent ev) {
157        // offset because the view is translated during swipe
158        ev.offsetLocation(mTranslationX, 0);
159
160        switch (ev.getActionMasked()) {
161            case MotionEvent.ACTION_DOWN:
162                resetMembers();
163                mDownX = ev.getRawX();
164                mDownY = ev.getRawY();
165                mActiveTouchId = ev.getPointerId(0);
166                mVelocityTracker = VelocityTracker.obtain();
167                mVelocityTracker.addMovement(ev);
168                break;
169
170            case MotionEvent.ACTION_POINTER_DOWN:
171                int actionIndex = ev.getActionIndex();
172                mActiveTouchId = ev.getPointerId(actionIndex);
173                break;
174            case MotionEvent.ACTION_POINTER_UP:
175                actionIndex = ev.getActionIndex();
176                int pointerId = ev.getPointerId(actionIndex);
177                if (pointerId == mActiveTouchId) {
178                    // This was our active pointer going up. Choose a new active pointer.
179                    int newActionIndex = actionIndex == 0 ? 1 : 0;
180                    mActiveTouchId = ev.getPointerId(newActionIndex);
181                }
182                break;
183
184            case MotionEvent.ACTION_CANCEL:
185            case MotionEvent.ACTION_UP:
186                resetMembers();
187                break;
188
189            case MotionEvent.ACTION_MOVE:
190                if (mVelocityTracker == null || mDiscardIntercept) {
191                    break;
192                }
193
194                int pointerIndex = ev.findPointerIndex(mActiveTouchId);
195                if (pointerIndex == -1) {
196                    Log.e(TAG, "Invalid pointer index: ignoring.");
197                    mDiscardIntercept = true;
198                    break;
199                }
200                float dx = ev.getRawX() - mDownX;
201                float x = ev.getX(pointerIndex);
202                float y = ev.getY(pointerIndex);
203                if (dx != 0 && canScroll(this, false, dx, x, y)) {
204                    mDiscardIntercept = true;
205                    break;
206                }
207                updateSwiping(ev);
208                break;
209        }
210
211        return !mDiscardIntercept && mSwiping;
212    }
213
214    @Override
215    public boolean onTouchEvent(MotionEvent ev) {
216        if (mVelocityTracker == null) {
217            return super.onTouchEvent(ev);
218        }
219        switch (ev.getActionMasked()) {
220            case MotionEvent.ACTION_UP:
221                updateDismiss(ev);
222                if (mDismissed) {
223                    dismiss();
224                } else if (mSwiping) {
225                    cancel();
226                }
227                resetMembers();
228                break;
229
230            case MotionEvent.ACTION_CANCEL:
231                cancel();
232                resetMembers();
233                break;
234
235            case MotionEvent.ACTION_MOVE:
236                mVelocityTracker.addMovement(ev);
237                mLastX = ev.getRawX();
238                updateSwiping(ev);
239                if (mSwiping) {
240                    if (mUseDynamicTranslucency && getContext() instanceof Activity) {
241                        ((Activity) getContext()).convertToTranslucent(null, null);
242                    }
243                    setProgress(ev.getRawX() - mDownX);
244                    break;
245                }
246        }
247        return true;
248    }
249
250    private void setProgress(float deltaX) {
251        mTranslationX = deltaX;
252        if (mProgressListener != null && deltaX >= 0)  {
253            mProgressListener.onSwipeProgressChanged(this, deltaX / getWidth(), deltaX);
254        }
255    }
256
257    private void dismiss() {
258        if (mDismissedListener != null) {
259            mDismissedListener.onDismissed(this);
260        }
261    }
262
263    protected void cancel() {
264        if (mUseDynamicTranslucency && getContext() instanceof Activity) {
265            ((Activity) getContext()).convertFromTranslucent();
266        }
267        if (mProgressListener != null) {
268            mProgressListener.onSwipeCancelled(this);
269        }
270    }
271
272    /**
273     * Resets internal members when canceling.
274     */
275    private void resetMembers() {
276        if (mVelocityTracker != null) {
277            mVelocityTracker.recycle();
278        }
279        mVelocityTracker = null;
280        mTranslationX = 0;
281        mDownX = 0;
282        mDownY = 0;
283        mSwiping = false;
284        mDismissed = false;
285        mDiscardIntercept = false;
286    }
287
288    private void updateSwiping(MotionEvent ev) {
289        if (!mSwiping) {
290            float deltaX = ev.getRawX() - mDownX;
291            float deltaY = ev.getRawY() - mDownY;
292            if ((deltaX * deltaX) + (deltaY * deltaY) > mSlop * mSlop) {
293                mSwiping = deltaX > mSlop * 2 && Math.abs(deltaY) < mSlop * 2;
294            } else {
295                mSwiping = false;
296            }
297        }
298    }
299
300    private void updateDismiss(MotionEvent ev) {
301        float deltaX = ev.getRawX() - mDownX;
302        if (!mDismissed) {
303            mVelocityTracker.addMovement(ev);
304            mVelocityTracker.computeCurrentVelocity(1000);
305
306            if (deltaX > (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO) &&
307                    ev.getRawX() >= mLastX) {
308                mDismissed = true;
309            }
310        }
311        // Check if the user tried to undo this.
312        if (mDismissed && mSwiping) {
313            // Check if the user's finger is actually back
314            if (deltaX < (getWidth() * DISMISS_MIN_DRAG_WIDTH_RATIO)) {
315                mDismissed = false;
316            }
317        }
318    }
319
320    /**
321     * Tests scrollability within child views of v in the direction of dx.
322     *
323     * @param v View to test for horizontal scrollability
324     * @param checkV Whether the view v passed should itself be checked for scrollability (true),
325     *               or just its children (false).
326     * @param dx Delta scrolled in pixels. Only the sign of this is used.
327     * @param x X coordinate of the active touch point
328     * @param y Y coordinate of the active touch point
329     * @return true if child views of v can be scrolled by delta of dx.
330     */
331    protected boolean canScroll(View v, boolean checkV, float dx, float x, float y) {
332        if (v instanceof ViewGroup) {
333            final ViewGroup group = (ViewGroup) v;
334            final int scrollX = v.getScrollX();
335            final int scrollY = v.getScrollY();
336            final int count = group.getChildCount();
337            for (int i = count - 1; i >= 0; i--) {
338                final View child = group.getChildAt(i);
339                if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
340                        y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
341                        canScroll(child, true, dx, x + scrollX - child.getLeft(),
342                                y + scrollY - child.getTop())) {
343                    return true;
344                }
345            }
346        }
347
348        return checkV && v.canScrollHorizontally((int) -dx);
349    }
350}
351