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      1 /*
      2  * Copyright (C) 2016 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.example.android.wearable.wear.wearnotifications;
     17 
     18 import android.support.v7.widget.RecyclerView;
     19 import android.support.wear.widget.WearableLinearLayoutManager;
     20 import android.support.wear.widget.WearableRecyclerView;
     21 import android.view.View;
     22 
     23 /**
     24  * Shrinks items (children) farther away from the center in a {@link WearableRecyclerView}. The UX
     25  * makes scrolling more readable.
     26  */
     27 public class ScalingScrollLayoutCallback extends WearableLinearLayoutManager.LayoutCallback {
     28 
     29     // Max we scale the child View.
     30     private static final float MAX_CHILD_SCALE = 0.65f;
     31 
     32     private float mProgressToCenter;
     33 
     34     /*
     35      * Scales the item's icons and text the farther away they are from center allowing the main
     36      * item to be more readable to the user on small devices like Wear.
     37      */
     38     @Override
     39     public void onLayoutFinished(View child, RecyclerView parent) {
     40 
     41         // Figure out % progress from top to bottom.
     42         float centerOffset = ((float) child.getHeight() / 2.0f) /  (float) parent.getHeight();
     43         float yRelativeToCenterOffset = (child.getY() / parent.getHeight()) + centerOffset;
     44 
     45         // Normalizes for center.
     46         mProgressToCenter = Math.abs(0.5f - yRelativeToCenterOffset);
     47 
     48         // Adjusts to the maximum scale.
     49         mProgressToCenter = Math.min(mProgressToCenter, MAX_CHILD_SCALE);
     50 
     51         child.setScaleX(1 - mProgressToCenter);
     52         child.setScaleY(1 - mProgressToCenter);
     53     }
     54 }