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 17 package com.android.systemui.statusbar.phone; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.view.MotionEvent; 22 import android.view.View; 23 import android.widget.ScrollView; 24 25 /** 26 * A scroll view which can be observed for scroll change events. 27 */ 28 public 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(ev); 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