TaskStackViewScroller.java revision 2536c7ed446203ea12b38cf05a88e603f8d1b768 
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.systemui.recents.views;
18
19import android.animation.Animator;
20import android.animation.AnimatorListenerAdapter;
21import android.animation.ObjectAnimator;
22import android.animation.ValueAnimator;
23import android.content.Context;
24import android.view.animation.AnimationUtils;
25import android.view.animation.Interpolator;
26import android.widget.OverScroller;
27import com.android.systemui.R;
28import com.android.systemui.recents.misc.Utilities;
29
30/* The scrolling logic for a TaskStackView */
31public class TaskStackViewScroller {
32    public interface TaskStackViewScrollerCallbacks {
33        public void onScrollChanged(float p);
34    }
35
36    Context mContext;
37    TaskStackViewLayoutAlgorithm mLayoutAlgorithm;
38    TaskStackViewScrollerCallbacks mCb;
39
40    float mStackScrollP;
41
42    OverScroller mScroller;
43    ObjectAnimator mScrollAnimator;
44    float mFinalAnimatedScroll;
45
46    Interpolator mLinearOutSlowInInterpolator;
47
48    public TaskStackViewScroller(Context context, TaskStackViewLayoutAlgorithm layoutAlgorithm) {
49        mContext = context;
50        mScroller = new OverScroller(context);
51        mLayoutAlgorithm = layoutAlgorithm;
52        mLinearOutSlowInInterpolator = AnimationUtils.loadInterpolator(context,
53                com.android.internal.R.interpolator.linear_out_slow_in);
54        setStackScroll(getStackScroll());
55    }
56
57    /** Resets the task scroller. */
58    void reset() {
59        mStackScrollP = 0f;
60    }
61
62    /** Sets the callbacks */
63    void setCallbacks(TaskStackViewScrollerCallbacks cb) {
64        mCb = cb;
65    }
66
67    /** Gets the current stack scroll */
68    public float getStackScroll() {
69        return mStackScrollP;
70    }
71
72    /** Sets the current stack scroll */
73    public void setStackScroll(float s) {
74        mStackScrollP = s;
75        if (mCb != null) {
76            mCb.onScrollChanged(mStackScrollP);
77        }
78    }
79
80    /** Sets the current stack scroll without calling the callback. */
81    void setStackScrollRaw(float s) {
82        mStackScrollP = s;
83    }
84
85    /**
86     * Sets the current stack scroll to the initial state when you first enter recents.
87     * @return whether the stack progress changed.
88     */
89    public boolean setStackScrollToInitialState() {
90        float prevStackScrollP = mStackScrollP;
91        setStackScroll(getBoundedStackScroll(mLayoutAlgorithm.mInitialScrollP));
92        return Float.compare(prevStackScrollP, mStackScrollP) != 0;
93    }
94
95    /** Bounds the current scroll if necessary */
96    public boolean boundScroll() {
97        float curScroll = getStackScroll();
98        float newScroll = getBoundedStackScroll(curScroll);
99        if (Float.compare(newScroll, curScroll) != 0) {
100            setStackScroll(newScroll);
101            return true;
102        }
103        return false;
104    }
105
106    /** Returns the bounded stack scroll */
107    float getBoundedStackScroll(float scroll) {
108        return Math.max(mLayoutAlgorithm.mMinScrollP, Math.min(mLayoutAlgorithm.mMaxScrollP, scroll));
109    }
110
111    /** Returns the amount that the absolute value of how much the scroll is out of bounds. */
112    float getScrollAmountOutOfBounds(float scroll) {
113        if (scroll < mLayoutAlgorithm.mMinScrollP) {
114            return Math.abs(scroll - mLayoutAlgorithm.mMinScrollP);
115        } else if (scroll > mLayoutAlgorithm.mMaxScrollP) {
116            return Math.abs(scroll - mLayoutAlgorithm.mMaxScrollP);
117        }
118        return 0f;
119    }
120
121    /** Returns whether the specified scroll is out of bounds */
122    boolean isScrollOutOfBounds() {
123        return Float.compare(getScrollAmountOutOfBounds(mStackScrollP), 0f) != 0;
124    }
125
126    /** Animates the stack scroll into bounds */
127    ObjectAnimator animateBoundScroll() {
128        float curScroll = getStackScroll();
129        float newScroll = getBoundedStackScroll(curScroll);
130        if (Float.compare(newScroll, curScroll) != 0) {
131            // Start a new scroll animation
132            animateScroll(curScroll, newScroll, null);
133        }
134        return mScrollAnimator;
135    }
136
137    /** Animates the stack scroll */
138    void animateScroll(float curScroll, float newScroll, final Runnable postRunnable) {
139        // Finish any current scrolling animations
140        if (mScrollAnimator != null && mScrollAnimator.isRunning()) {
141            setStackScroll(mFinalAnimatedScroll);
142            mScroller.startScroll(0, progressToScrollRange(mFinalAnimatedScroll), 0, 0, 0);
143        }
144        stopScroller();
145        stopBoundScrollAnimation();
146
147        mFinalAnimatedScroll = newScroll;
148        mScrollAnimator = ObjectAnimator.ofFloat(this, "stackScroll", curScroll, newScroll);
149        mScrollAnimator.setDuration(mContext.getResources().getInteger(
150                R.integer.recents_animate_task_stack_scroll_duration));
151        mScrollAnimator.setInterpolator(mLinearOutSlowInInterpolator);
152        mScrollAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
153            @Override
154            public void onAnimationUpdate(ValueAnimator animation) {
155                setStackScroll((Float) animation.getAnimatedValue());
156            }
157        });
158        mScrollAnimator.addListener(new AnimatorListenerAdapter() {
159            @Override
160            public void onAnimationEnd(Animator animation) {
161                if (postRunnable != null) {
162                    postRunnable.run();
163                }
164                mScrollAnimator.removeAllListeners();
165            }
166        });
167        mScrollAnimator.start();
168    }
169
170    /** Aborts any current stack scrolls */
171    void stopBoundScrollAnimation() {
172        Utilities.cancelAnimationWithoutCallbacks(mScrollAnimator);
173    }
174
175    /**** OverScroller ****/
176
177    int progressToScrollRange(float p) {
178        return (int) (p * mLayoutAlgorithm.mStackVisibleRect.height());
179    }
180
181    float scrollRangeToProgress(int s) {
182        return (float) s / mLayoutAlgorithm.mStackVisibleRect.height();
183    }
184
185    /** Called from the view draw, computes the next scroll. */
186    boolean computeScroll() {
187        if (mScroller.computeScrollOffset()) {
188            float scroll = scrollRangeToProgress(mScroller.getCurrY());
189            setStackScrollRaw(scroll);
190            if (mCb != null) {
191                mCb.onScrollChanged(scroll);
192            }
193            return true;
194        }
195        return false;
196    }
197
198    /** Returns whether the overscroller is scrolling. */
199    boolean isScrolling() {
200        return !mScroller.isFinished();
201    }
202
203    /** Stops the scroller and any current fling. */
204    void stopScroller() {
205        if (!mScroller.isFinished()) {
206            mScroller.abortAnimation();
207        }
208    }
209}