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.wearable.view.DefaultOffsettingHelper;
19 import android.support.wearable.view.WearableRecyclerView;
20 import android.view.View;
21 
22 /**
23  * Customizes all items (children) in a {@link WearableRecyclerView} to align to left side of
24  * surface/watch and shrinks each item (child) as you scroll away from it.
25  */
26 public class ScalingOffsettingHelper extends DefaultOffsettingHelper {
27 
28     // Max we scale the child View
29     private static final float MAX_CHILD_SCALE = 0.65f;
30 
31     private float mProgressToCenter;
32 
ScalingOffsettingHelper()33     public ScalingOffsettingHelper() {}
34 
35     // Shrinks icons/text and you scroll away
36     @Override
updateChild(View child, WearableRecyclerView parent)37     public void updateChild(View child, WearableRecyclerView parent) {
38         super.updateChild(child, parent);
39 
40         // Figure out % progress from top to bottom
41         float centerOffset = ((float) child.getHeight() / 2.0f) /  (float) parent.getHeight();
42         float yRelativeToCenterOffset = (child.getY() / parent.getHeight()) + centerOffset;
43 
44         // Normalize for center
45         mProgressToCenter = Math.abs(0.5f - yRelativeToCenterOffset);
46 
47         // Adjust to the maximum scale
48         mProgressToCenter = Math.min(mProgressToCenter, MAX_CHILD_SCALE);
49 
50         child.setScaleX(1 - mProgressToCenter);
51         child.setScaleY(1 - mProgressToCenter);
52     }
53 }