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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 
     17 package com.example.android.slidingfragments;
     18 
     19 import android.content.Context;
     20 import android.util.AttributeSet;
     21 import android.widget.LinearLayout;
     22 
     23 /**
     24  * In order to animate the fragment containing text on/off the screen,
     25  * it is required that we know the height of the device being used. However,
     26  * this can only be determined at runtime, so we cannot specify the required
     27  * translation in an xml file. Since FragmentTransaction's setCustomAnimations
     28  * method requires an ID of an animation defined via an xml file, this linear
     29  * layout was built as a workaround. This custom linear layout is created to specify
     30  * the location of the fragment's layout as a fraction of the device's height. By
     31  * animating yFraction from 0 to 1, we can animate the fragment from the top of
     32  * the screen to the bottom of the screen, regardless of the device's specific size.
     33  */
     34 public class FractionalLinearLayout extends LinearLayout {
     35 
     36     private float mYFraction;
     37     private int mScreenHeight;
     38 
     39     public FractionalLinearLayout(Context context) {
     40         super(context);
     41     }
     42 
     43     public FractionalLinearLayout(Context context, AttributeSet attrs) {
     44         super(context, attrs);
     45     }
     46 
     47     @Override
     48     protected void onSizeChanged (int w, int h, int oldw, int oldh) {
     49         super.onSizeChanged(w, h, oldw, oldh);
     50         mScreenHeight = h;
     51         setY(mScreenHeight);
     52     }
     53 
     54     public float getYFraction() {
     55         return mYFraction;
     56     }
     57 
     58     public void setYFraction(float yFraction) {
     59         mYFraction = yFraction;
     60         setY((mScreenHeight > 0) ? (mScreenHeight - yFraction * mScreenHeight) : 0);
     61     }
     62 }
     63