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      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.launcher3;
     18 
     19 public class SpringLoadedDragController implements OnAlarmListener {
     20     // how long the user must hover over a mini-screen before it unshrinks
     21     final long ENTER_SPRING_LOAD_HOVER_TIME = 500;
     22     final long ENTER_SPRING_LOAD_CANCEL_HOVER_TIME = 950;
     23     final long EXIT_SPRING_LOAD_HOVER_TIME = 200;
     24 
     25     Alarm mAlarm;
     26 
     27     // the screen the user is currently hovering over, if any
     28     private CellLayout mScreen;
     29     private Launcher mLauncher;
     30 
     31     public SpringLoadedDragController(Launcher launcher) {
     32         mLauncher = launcher;
     33         mAlarm = new Alarm();
     34         mAlarm.setOnAlarmListener(this);
     35     }
     36 
     37     public void cancel() {
     38         mAlarm.cancelAlarm();
     39     }
     40 
     41     // Set a new alarm to expire for the screen that we are hovering over now
     42     public void setAlarm(CellLayout cl) {
     43         mAlarm.cancelAlarm();
     44         mAlarm.setAlarm((cl == null) ? ENTER_SPRING_LOAD_CANCEL_HOVER_TIME :
     45             ENTER_SPRING_LOAD_HOVER_TIME);
     46         mScreen = cl;
     47     }
     48 
     49     // this is called when our timer runs out
     50     public void onAlarm(Alarm alarm) {
     51         if (mScreen != null) {
     52             // Snap to the screen that we are hovering over now
     53             Workspace w = mLauncher.getWorkspace();
     54             int page = w.indexOfChild(mScreen);
     55             if (page != w.getCurrentPage()) {
     56                 w.snapToPage(page);
     57             }
     58         } else {
     59             mLauncher.getDragController().cancelDrag();
     60         }
     61     }
     62 }
     63