Owen Lin | f9a0a43 | 2011-08-17 22:07:43 +0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2010 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.gallery3d.ui; |
| 18 | |
| 19 | import com.android.gallery3d.common.Utils; |
| 20 | |
| 21 | import android.content.Context; |
| 22 | import android.view.ViewConfiguration; |
| 23 | import android.widget.OverScroller; |
| 24 | |
| 25 | public class ScrollerHelper { |
| 26 | private OverScroller mScroller; |
| 27 | private int mOverflingDistance; |
| 28 | private boolean mOverflingEnabled; |
| 29 | |
| 30 | public ScrollerHelper(Context context) { |
| 31 | mScroller = new OverScroller(context); |
| 32 | ViewConfiguration configuration = ViewConfiguration.get(context); |
| 33 | mOverflingDistance = configuration.getScaledOverflingDistance(); |
| 34 | } |
| 35 | |
| 36 | public void setOverfling(boolean enabled) { |
| 37 | mOverflingEnabled = enabled; |
| 38 | } |
| 39 | |
| 40 | /** |
| 41 | * Call this when you want to know the new location. The position will be |
| 42 | * updated and can be obtained by getPosition(). Returns true if the |
| 43 | * animation is not yet finished. |
| 44 | */ |
| 45 | public boolean advanceAnimation(long currentTimeMillis) { |
| 46 | return mScroller.computeScrollOffset(); |
| 47 | } |
| 48 | |
| 49 | public boolean isFinished() { |
| 50 | return mScroller.isFinished(); |
| 51 | } |
| 52 | |
| 53 | public void forceFinished() { |
| 54 | mScroller.forceFinished(true); |
| 55 | } |
| 56 | |
| 57 | public int getPosition() { |
| 58 | return mScroller.getCurrX(); |
| 59 | } |
| 60 | |
| 61 | public void setPosition(int position) { |
| 62 | mScroller.startScroll( |
| 63 | position, 0, // startX, startY |
| 64 | 0, 0, 0); // dx, dy, duration |
| 65 | |
| 66 | // This forces the scroller to reach the final position. |
| 67 | mScroller.abortAnimation(); |
| 68 | } |
| 69 | |
| 70 | public void fling(int velocity, int min, int max) { |
| 71 | int currX = getPosition(); |
| 72 | mScroller.fling( |
| 73 | currX, 0, // startX, startY |
| 74 | velocity, 0, // velocityX, velocityY |
| 75 | min, max, // minX, maxX |
| 76 | 0, 0, // minY, maxY |
| 77 | mOverflingEnabled ? mOverflingDistance : 0, 0); |
| 78 | } |
| 79 | |
| 80 | public boolean startScroll(int distance, int min, int max) { |
| 81 | int currPosition = mScroller.getCurrX(); |
| 82 | int finalPosition = mScroller.getFinalX(); |
| 83 | int newPosition = Utils.clamp(finalPosition + distance, min, max); |
| 84 | if (newPosition != currPosition) { |
| 85 | mScroller.startScroll( |
| 86 | currPosition, 0, // startX, startY |
| 87 | newPosition - currPosition, 0, 0); // dx, dy, duration |
| 88 | return true; |
| 89 | } else { |
| 90 | return false; |
| 91 | } |
| 92 | } |
| 93 | } |