1 /*
2  * Copyright (C) 2022 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 android.inputmethodservice.navigationbar;
18 
19 import android.annotation.Nullable;
20 import android.content.Context;
21 import android.util.AttributeSet;
22 import android.view.Gravity;
23 import android.view.View;
24 import android.view.ViewGroup;
25 import android.widget.LinearLayout;
26 import android.widget.RelativeLayout;
27 
28 import java.util.ArrayList;
29 
30 /**
31  * Automatically reverses the order of children as they are added.
32  * Also reverse the width and height values of layout params
33  */
34 class ReverseLinearLayout extends LinearLayout {
35 
36     /** If true, the layout is reversed vs. a regular linear layout */
37     private boolean mIsLayoutReverse;
38 
39     /** If true, the layout is opposite to it's natural reversity from the layout direction */
40     private boolean mIsAlternativeOrder;
41 
ReverseLinearLayout(Context context, @Nullable AttributeSet attrs)42     ReverseLinearLayout(Context context, @Nullable AttributeSet attrs) {
43         super(context, attrs);
44     }
45 
46     @Override
onFinishInflate()47     protected void onFinishInflate() {
48         super.onFinishInflate();
49         updateOrder();
50     }
51 
52     @Override
addView(View child)53     public void addView(View child) {
54         reverseParams(child.getLayoutParams(), child, mIsLayoutReverse);
55         if (mIsLayoutReverse) {
56             super.addView(child, 0);
57         } else {
58             super.addView(child);
59         }
60     }
61 
62     @Override
addView(View child, ViewGroup.LayoutParams params)63     public void addView(View child, ViewGroup.LayoutParams params) {
64         reverseParams(params, child, mIsLayoutReverse);
65         if (mIsLayoutReverse) {
66             super.addView(child, 0, params);
67         } else {
68             super.addView(child, params);
69         }
70     }
71 
72     @Override
onRtlPropertiesChanged(int layoutDirection)73     public void onRtlPropertiesChanged(int layoutDirection) {
74         super.onRtlPropertiesChanged(layoutDirection);
75         updateOrder();
76     }
77 
setAlternativeOrder(boolean alternative)78     public void setAlternativeOrder(boolean alternative) {
79         mIsAlternativeOrder = alternative;
80         updateOrder();
81     }
82 
83     /**
84      * In landscape, the LinearLayout is not auto mirrored since it is vertical. Therefore we
85      * have to do it manually
86      */
updateOrder()87     private void updateOrder() {
88         boolean isLayoutRtl = getLayoutDirection() == LAYOUT_DIRECTION_RTL;
89         boolean isLayoutReverse = isLayoutRtl ^ mIsAlternativeOrder;
90 
91         if (mIsLayoutReverse != isLayoutReverse) {
92             // reversity changed, swap the order of all views.
93             int childCount = getChildCount();
94             ArrayList<View> childList = new ArrayList<>(childCount);
95             for (int i = 0; i < childCount; i++) {
96                 childList.add(getChildAt(i));
97             }
98             removeAllViews();
99             for (int i = childCount - 1; i >= 0; i--) {
100                 final View child = childList.get(i);
101                 super.addView(child);
102             }
103             mIsLayoutReverse = isLayoutReverse;
104         }
105     }
106 
reverseParams(ViewGroup.LayoutParams params, View child, boolean isLayoutReverse)107     private static void reverseParams(ViewGroup.LayoutParams params, View child,
108             boolean isLayoutReverse) {
109         if (child instanceof Reversible) {
110             ((Reversible) child).reverse(isLayoutReverse);
111         }
112         if (child.getPaddingLeft() == child.getPaddingRight()
113                 && child.getPaddingTop() == child.getPaddingBottom()) {
114             child.setPadding(child.getPaddingTop(), child.getPaddingLeft(),
115                     child.getPaddingTop(), child.getPaddingLeft());
116         }
117         if (params == null) {
118             return;
119         }
120         int width = params.width;
121         params.width = params.height;
122         params.height = width;
123     }
124 
125     interface Reversible {
reverse(boolean isLayoutReverse)126         void reverse(boolean isLayoutReverse);
127     }
128 
129     public static class ReverseRelativeLayout extends RelativeLayout implements Reversible {
130 
ReverseRelativeLayout(Context context)131         ReverseRelativeLayout(Context context) {
132             super(context);
133         }
134 
135         @Override
reverse(boolean isLayoutReverse)136         public void reverse(boolean isLayoutReverse) {
137             updateGravity(isLayoutReverse);
138             reverseGroup(this, isLayoutReverse);
139         }
140 
141         private int mDefaultGravity = Gravity.NO_GRAVITY;
setDefaultGravity(int gravity)142         public void setDefaultGravity(int gravity) {
143             mDefaultGravity = gravity;
144         }
145 
updateGravity(boolean isLayoutReverse)146         public void updateGravity(boolean isLayoutReverse) {
147             // Flip gravity if top of bottom is used
148             if (mDefaultGravity != Gravity.TOP && mDefaultGravity != Gravity.BOTTOM) return;
149 
150             // Use the default (intended for 270 LTR and 90 RTL) unless layout is otherwise
151             int gravityToApply = mDefaultGravity;
152             if (isLayoutReverse) {
153                 gravityToApply = mDefaultGravity == Gravity.TOP ? Gravity.BOTTOM : Gravity.TOP;
154             }
155 
156             if (getGravity() != gravityToApply) setGravity(gravityToApply);
157         }
158     }
159 
reverseGroup(ViewGroup group, boolean isLayoutReverse)160     private static void reverseGroup(ViewGroup group, boolean isLayoutReverse) {
161         for (int i = 0; i < group.getChildCount(); i++) {
162             final View child = group.getChildAt(i);
163             reverseParams(child.getLayoutParams(), child, isLayoutReverse);
164 
165             // Recursively reverse all children
166             if (child instanceof ViewGroup) {
167                 reverseGroup((ViewGroup) child, isLayoutReverse);
168             }
169         }
170     }
171 }
172