1 /*
2  * Copyright (C) 2020 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.android.systemui.statusbar.notification.collection.render
18 
19 import android.view.View
20 import java.lang.RuntimeException
21 import java.lang.StringBuilder
22 
23 /**
24  * A controller that represents a single unit of addable/removable view(s) in the notification
25  * shade. Some nodes are just a single view (such as a header), while some might involve many views
26  * (such as a notification row).
27  *
28  * It's possible for nodes to support having child nodes (for example, some notification rows
29  * contain other notification rows). If so, they must implement all of the child-related methods
30  * below.
31  */
32 interface NodeController {
33 
34     /** A string that uniquely(ish) represents the node in the tree. Used for debugging. */
35     val nodeLabel: String
36 
37     val view: View
38 
39     fun getChildAt(index: Int): View? {
40         throw RuntimeException("Not supported")
41     }
42 
43     fun getChildCount(): Int = 0
44 
45     /** Called to add a child to this view */
46     fun addChildAt(child: NodeController, index: Int) {
47         throw RuntimeException("Not supported")
48     }
49 
50     /** Called to move one of this view's current children to a new position */
51     fun moveChildTo(child: NodeController, index: Int) {
52         throw RuntimeException("Not supported")
53     }
54 
55     /** Called to remove one of this view's current children */
56     fun removeChild(child: NodeController, isTransfer: Boolean) {
57         throw RuntimeException("Not supported")
58     }
59 
60     /** Called when this view has been added */
61     fun onViewAdded() {}
62 
63     /** Called when this view has been moved */
64     fun onViewMoved() {}
65 
66     /** Called when this view has been removed */
67     fun onViewRemoved() {}
68 
69     /**
70      * Called before removing a node from its parent
71      *
72      * If returned true, the ShadeViewDiffer won't detach this row and the view system is
73      * responsible for ensuring the row is in eventually removed from the parent.
74      *
75      * @return false to opt out from this feature
76      */
77     fun offerToKeepInParentForAnimation(): Boolean
78 
79     /**
80      * Called before a node is reattached. Removes the view from its parent
81      * if it was flagged to be kept before.
82      *
83      * @return whether it did a removal
84      */
85     fun removeFromParentIfKeptForAnimation(): Boolean
86 
87     /** Called when a node is being reattached */
88     fun resetKeepInParentForAnimation()
89 }
90 
91 /**
92  * Used to specify the tree of [NodeController]s that currently make up the shade.
93  */
94 interface NodeSpec {
95     val parent: NodeSpec?
96     val controller: NodeController
97     val children: List<NodeSpec>
98 }
99 
100 class NodeSpecImpl(
101     override val parent: NodeSpec?,
102     override val controller: NodeController
103 ) : NodeSpec {
104     override val children = mutableListOf<NodeSpec>()
105 }
106 
107 /**
108  * Converts a tree spec to human-readable string, for dumping purposes.
109  */
110 fun treeSpecToStr(tree: NodeSpec): String {
111     return StringBuilder().also { treeSpecToStrHelper(tree, it, "") }.toString()
112 }
113 
114 private fun treeSpecToStrHelper(tree: NodeSpec, sb: StringBuilder, indent: String) {
115     sb.append("$indent{${tree.controller.nodeLabel}}\n")
116     if (tree.children.isNotEmpty()) {
117         val childIndent = "$indent  "
118         for (child in tree.children) {
119             treeSpecToStrHelper(child, sb, childIndent)
120         }
121     }
122 }
123