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.statusbar.phone;
18
19import android.content.Context;
20import android.util.AttributeSet;
21import android.view.MotionEvent;
22import android.view.View;
23import android.widget.ScrollView;
24
25/**
26 * A scroll view which can be observed for scroll change events.
27 */
28public class ObservableScrollView extends ScrollView {
29
30    private Listener mListener;
31    private int mLastOverscrollAmount;
32    private boolean mTouchEnabled = true;
33    private boolean mHandlingTouchEvent;
34    private float mLastX;
35    private float mLastY;
36    private boolean mBlockFlinging;
37    private boolean mTouchCancelled;
38
39    public ObservableScrollView(Context context, AttributeSet attrs) {
40        super(context, attrs);
41    }
42
43    public void setListener(Listener listener) {
44        mListener = listener;
45    }
46
47    public void setTouchEnabled(boolean touchEnabled) {
48        mTouchEnabled = touchEnabled;
49    }
50
51    public boolean isScrolledToBottom() {
52        return getScrollY() == getMaxScrollY();
53    }
54
55    public boolean isHandlingTouchEvent() {
56        return mHandlingTouchEvent;
57    }
58
59    private int getMaxScrollY() {
60        int scrollRange = 0;
61        if (getChildCount() > 0) {
62            View child = getChildAt(0);
63            scrollRange = Math.max(0,
64                    child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop));
65        }
66        return scrollRange;
67    }
68
69    @Override
70    public boolean onTouchEvent(MotionEvent ev) {
71        mHandlingTouchEvent = true;
72        mLastX = ev.getX();
73        mLastY = ev.getY();
74        boolean result = super.onTouchEvent(ev);
75        mHandlingTouchEvent = false;
76        return result;
77    }
78
79    @Override
80    public boolean onInterceptTouchEvent(MotionEvent ev) {
81        mHandlingTouchEvent = true;
82        mLastX = ev.getX();
83        mLastY = ev.getY();
84        boolean result = super.onInterceptTouchEvent(ev);
85        mHandlingTouchEvent = false;
86        return result;
87    }
88
89    @Override
90    public boolean dispatchTouchEvent(MotionEvent ev) {
91        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
92            if (!mTouchEnabled) {
93                mTouchCancelled = true;
94                return false;
95            }
96            mTouchCancelled = false;
97        } else if (mTouchCancelled) {
98            return false;
99        } else if (!mTouchEnabled) {
100            MotionEvent cancel = MotionEvent.obtain(ev);
101            cancel.setAction(MotionEvent.ACTION_CANCEL);
102            super.dispatchTouchEvent(cancel);
103            cancel.recycle();
104            mTouchCancelled = true;
105            return false;
106        }
107        return super.dispatchTouchEvent(ev);
108    }
109
110    @Override
111    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
112        super.onScrollChanged(l, t, oldl, oldt);
113        if (mListener != null) {
114            mListener.onScrollChanged();
115        }
116    }
117
118    @Override
119    protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY,
120            int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY,
121            boolean isTouchEvent) {
122        mLastOverscrollAmount = Math.max(0, scrollY + deltaY - getMaxScrollY());
123        return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY,
124                        maxOverScrollX, maxOverScrollY, isTouchEvent);
125    }
126
127    public void setBlockFlinging(boolean blockFlinging) {
128        mBlockFlinging = blockFlinging;
129    }
130
131    @Override
132    public void fling(int velocityY) {
133        if (!mBlockFlinging) {
134            super.fling(velocityY);
135        }
136    }
137
138    @Override
139    protected void onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY) {
140        super.onOverScrolled(scrollX, scrollY, clampedX, clampedY);
141        if (mListener != null && mLastOverscrollAmount > 0) {
142            mListener.onOverscrolled(mLastX, mLastY, mLastOverscrollAmount);
143        }
144    }
145
146    public interface Listener {
147        void onScrollChanged();
148        void onOverscrolled(float lastX, float lastY, int amount);
149    }
150}
151