1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
5  * except in compliance with the License. You may obtain a copy of the License at
6  *
7  *      http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the
10  * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
11  * KIND, either express or implied. See the License for the specific language governing
12  * permissions and limitations under the License.
13  */
14 
15 package com.android.systemui.statusbar.phone;
16 
17 import android.annotation.Nullable;
18 import android.content.Context;
19 import android.util.AttributeSet;
20 import android.view.Gravity;
21 import android.view.View;
22 import android.view.ViewGroup;
23 import android.widget.LinearLayout;
24 import android.widget.RelativeLayout;
25 
26 import java.util.ArrayList;
27 
28 /**
29  * Automatically reverses the order of children as they are added.
30  * Also reverse the width and height values of layout params
31  */
32 public class ReverseLinearLayout extends LinearLayout {
33 
34     /** If true, the layout is reversed vs. a regular linear layout */
35     private boolean mIsLayoutReverse;
36 
37     /** If true, the layout is opposite to it's natural reversity from the layout direction */
38     private boolean mIsAlternativeOrder;
39 
ReverseLinearLayout(Context context, @Nullable AttributeSet attrs)40     public ReverseLinearLayout(Context context, @Nullable AttributeSet attrs) {
41         super(context, attrs);
42     }
43 
44     @Override
onFinishInflate()45     protected void onFinishInflate() {
46         super.onFinishInflate();
47         updateOrder();
48     }
49 
50     @Override
addView(View child)51     public void addView(View child) {
52         reverseParams(child.getLayoutParams(), child, mIsLayoutReverse);
53         if (mIsLayoutReverse) {
54             super.addView(child, 0);
55         } else {
56             super.addView(child);
57         }
58     }
59 
60     @Override
addView(View child, ViewGroup.LayoutParams params)61     public void addView(View child, ViewGroup.LayoutParams params) {
62         reverseParams(params, child, mIsLayoutReverse);
63         if (mIsLayoutReverse) {
64             super.addView(child, 0, params);
65         } else {
66             super.addView(child, params);
67         }
68     }
69 
70     @Override
onRtlPropertiesChanged(int layoutDirection)71     public void onRtlPropertiesChanged(int layoutDirection) {
72         super.onRtlPropertiesChanged(layoutDirection);
73         updateOrder();
74     }
75 
setAlternativeOrder(boolean alternative)76     public void setAlternativeOrder(boolean alternative) {
77         mIsAlternativeOrder = alternative;
78         updateOrder();
79     }
80 
81     /**
82      * In landscape, the LinearLayout is not auto mirrored since it is vertical. Therefore we
83      * have to do it manually
84      */
updateOrder()85     private void updateOrder() {
86         boolean isLayoutRtl = getLayoutDirection() == LAYOUT_DIRECTION_RTL;
87         boolean isLayoutReverse = isLayoutRtl ^ mIsAlternativeOrder;
88 
89         if (mIsLayoutReverse != isLayoutReverse) {
90             // reversity changed, swap the order of all views.
91             int childCount = getChildCount();
92             ArrayList<View> childList = new ArrayList<>(childCount);
93             for (int i = 0; i < childCount; i++) {
94                 childList.add(getChildAt(i));
95             }
96             removeAllViews();
97             for (int i = childCount - 1; i >= 0; i--) {
98                 final View child = childList.get(i);
99                 super.addView(child);
100             }
101             mIsLayoutReverse = isLayoutReverse;
102         }
103     }
104 
reverseParams(ViewGroup.LayoutParams params, View child, boolean isLayoutReverse)105     private static void reverseParams(ViewGroup.LayoutParams params, View child,
106             boolean isLayoutReverse) {
107         if (child instanceof Reversable) {
108             ((Reversable) child).reverse(isLayoutReverse);
109         }
110         if (child.getPaddingLeft() == child.getPaddingRight()
111                 && child.getPaddingTop() == child.getPaddingBottom()) {
112             child.setPadding(child.getPaddingTop(), child.getPaddingLeft(),
113                     child.getPaddingTop(), child.getPaddingLeft());
114         }
115         if (params == null) {
116             return;
117         }
118         int width = params.width;
119         params.width = params.height;
120         params.height = width;
121     }
122 
123     public interface Reversable {
reverse(boolean isLayoutReverse)124         void reverse(boolean isLayoutReverse);
125     }
126 
127     public static class ReverseRelativeLayout extends RelativeLayout implements Reversable {
128 
ReverseRelativeLayout(Context context)129         public ReverseRelativeLayout(Context context) {
130             super(context);
131         }
132 
133         @Override
reverse(boolean isLayoutReverse)134         public void reverse(boolean isLayoutReverse) {
135             updateGravity(isLayoutReverse);
136             reverseGroup(this, isLayoutReverse);
137         }
138 
139         private int mDefaultGravity = Gravity.NO_GRAVITY;
setDefaultGravity(int gravity)140         public void setDefaultGravity(int gravity) {
141             mDefaultGravity = gravity;
142         }
143 
updateGravity(boolean isLayoutReverse)144         public void updateGravity(boolean isLayoutReverse) {
145             // Flip gravity if top of bottom is used
146             if (mDefaultGravity != Gravity.TOP && mDefaultGravity != Gravity.BOTTOM) return;
147 
148             // Use the default (intended for 270 LTR and 90 RTL) unless layout is otherwise
149             int gravityToApply = mDefaultGravity;
150             if (isLayoutReverse) {
151                 gravityToApply = mDefaultGravity == Gravity.TOP ? Gravity.BOTTOM : Gravity.TOP;
152             }
153 
154             if (getGravity() != gravityToApply) setGravity(gravityToApply);
155         }
156     }
157 
reverseGroup(ViewGroup group, boolean isLayoutReverse)158     private static void reverseGroup(ViewGroup group, boolean isLayoutReverse) {
159         for (int i = 0; i < group.getChildCount(); i++) {
160             final View child = group.getChildAt(i);
161             reverseParams(child.getLayoutParams(), child, isLayoutReverse);
162 
163             // Recursively reverse all children
164             if (child instanceof ViewGroup) {
165                 reverseGroup((ViewGroup) child, isLayoutReverse);
166             }
167         }
168     }
169 
170 }
171