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      1 /*
      2  * Copyright (C) 2013 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 package com.android.dreams.phototable;
     17 
     18 import android.content.Context;
     19 import android.content.res.Resources;
     20 import android.view.MotionEvent;
     21 
     22 /**
     23  * Detect and dispatch edge events.
     24  */
     25 public class DragGestureDetector {
     26     @SuppressWarnings("unused")
     27     private static final String TAG = "DragGestureDetector";
     28 
     29     private final PhotoTable mTable;
     30     private final float mTouchGain;
     31 
     32     private float[] mLast;
     33     private float[] mCurrent;
     34     private boolean mDrag;
     35 
     36     public DragGestureDetector(Context context, PhotoTable table) {
     37         Resources res = context.getResources();
     38         mTouchGain = res.getInteger(R.integer.generalized_touch_gain) / 1000000f;
     39         mTable = table;
     40         mLast = new float[2];
     41         mCurrent = new float[2];
     42     }
     43 
     44     private void computeAveragePosition(MotionEvent event, float[] position) {
     45         computeAveragePosition(event, position, -1);
     46     }
     47 
     48     private void computeAveragePosition(MotionEvent event, float[] position, int ignore) {
     49         final int pointerCount = event.getPointerCount();
     50         position[0] = 0f;
     51         position[1] = 0f;
     52         float count = 0f;
     53         for (int p = 0; p < pointerCount; p++) {
     54             if (p != ignore) {
     55                 position[0] += event.getX(p);
     56                 position[1] += event.getY(p);
     57                 count += 1f;
     58             }
     59         }
     60         position[0] /= count;
     61         position[1] /= count;
     62     }
     63 
     64     public boolean onTouchEvent(MotionEvent event) {
     65         int index = event.getActionIndex();
     66         switch (event.getActionMasked()) {
     67             case MotionEvent.ACTION_DOWN:
     68                 computeAveragePosition(event, mLast);
     69                 mDrag = false;
     70                 break;
     71 
     72             case MotionEvent.ACTION_POINTER_DOWN:
     73                 mDrag = mTable.hasFocus();
     74                 computeAveragePosition(event, mLast);
     75                 break;
     76 
     77             case MotionEvent.ACTION_POINTER_UP:
     78                 computeAveragePosition(event, mLast, index);
     79                 break;
     80 
     81             case MotionEvent.ACTION_MOVE:
     82                 computeAveragePosition(event, mCurrent);
     83                 if (mDrag) {
     84                     move(event, false);
     85                 }
     86                 break;
     87 
     88             case MotionEvent.ACTION_CANCEL:
     89             case MotionEvent.ACTION_UP:
     90                 if (mDrag) {
     91                     move(event, true);
     92                 }
     93                 mDrag = false;
     94                 break;
     95         }
     96 
     97         if (mDrag) {
     98             mTable.refreshFocus();
     99         }
    100 
    101         return mDrag;
    102     }
    103 
    104     private void move(MotionEvent event, boolean drop) {
    105         mTable.move(mTable.getFocus(),
    106                 mTouchGain * (mCurrent[0] - mLast[0]),
    107                 mTouchGain * (mCurrent[1] - mLast[1]),
    108                 drop);
    109         mLast[0] = mCurrent[0];
    110         mLast[1] = mCurrent[1];
    111     }
    112 }
    113 
    114