FocusEventModifier.kt
/*
* Copyright 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.compose.ui.focus
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.InspectorInfo
import androidx.compose.ui.platform.InspectorValueInfo
import androidx.compose.ui.platform.debugInspectorInfo
/**
* A [modifier][Modifier.Element] that can be used to observe focus state events.
*/
interface FocusEventModifier : Modifier.Element {
/**
* A callback that is called whenever the focus system raises events.
*/
fun onFocusEvent(focusState: FocusState)
}
internal class FocusEventModifierImpl(
val onFocusEvent: (FocusState) -> Unit,
inspectorInfo: InspectorInfo.() -> Unit
) : FocusEventModifier, InspectorValueInfo(inspectorInfo) {
override fun onFocusEvent(focusState: FocusState) {
onFocusEvent.invoke(focusState)
}
}
/**
* Add this modifier to a component to observe focus state events.
*/
fun Modifier.onFocusEvent(onFocusEvent: (FocusState) -> Unit): Modifier {
return this.then(
FocusEventModifierImpl(
onFocusEvent = onFocusEvent,
inspectorInfo = debugInspectorInfo {
name = "onFocusEvent"
properties["onFocusEvent"] = onFocusEvent
}
)
)
}