1 /*
2  * Copyright 2023 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 androidx.compose.ui.focus
18 
19 import androidx.compose.ui.Modifier
20 import androidx.compose.ui.internal.JvmDefaultWithCompatibility
21 import androidx.compose.ui.node.ModifierNodeElement
22 import androidx.compose.ui.platform.InspectorInfo
23 
24 /** A [modifier][Modifier.Element] that can be used to observe focus state events. */
25 @Deprecated("Use FocusEventModifierNode instead")
26 @JvmDefaultWithCompatibility
27 interface FocusEventModifier : Modifier.Element {
28     /** A callback that is called whenever the focus system raises events. */
onFocusEventnull29     fun onFocusEvent(focusState: FocusState)
30 }
31 
32 /** Add this modifier to a component to observe focus state events. */
33 fun Modifier.onFocusEvent(onFocusEvent: (FocusState) -> Unit): Modifier =
34     this then FocusEventElement(onFocusEvent)
35 
36 private class FocusEventElement(val onFocusEvent: (FocusState) -> Unit) :
37     ModifierNodeElement<FocusEventNode>() {
38     override fun create() = FocusEventNode(onFocusEvent)
39 
40     override fun update(node: FocusEventNode) {
41         node.onFocusEvent = onFocusEvent
42     }
43 
44     override fun InspectorInfo.inspectableProperties() {
45         name = "onFocusEvent"
46         properties["onFocusEvent"] = onFocusEvent
47     }
48 
49     override fun equals(other: Any?): Boolean {
50         if (this === other) return true
51         if (other !is FocusEventElement) return false
52 
53         if (onFocusEvent !== other.onFocusEvent) return false
54 
55         return true
56     }
57 
58     override fun hashCode(): Int {
59         return onFocusEvent.hashCode()
60     }
61 }
62 
63 private class FocusEventNode(var onFocusEvent: (FocusState) -> Unit) :
64     FocusEventModifierNode, Modifier.Node() {
65 
onFocusEventnull66     override fun onFocusEvent(focusState: FocusState) {
67         this.onFocusEvent.invoke(focusState)
68     }
69 }
70