| /* |
| * 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.ExperimentalComposeUiApi |
| import androidx.compose.ui.Modifier |
| import androidx.compose.ui.node.modifierElementOf |
| |
| /** |
| * Add this modifier to a component to observe focus state events. [onFocusChanged] is invoked |
| * when the focus state changes. The [onFocusChanged] modifier listens to the state of the first |
| * [focusTarget] following this modifier. |
| * |
| * @sample androidx.compose.ui.samples.FocusableSample |
| * |
| * Note: If you want to be notified every time the internal focus state is written to (even if it |
| * hasn't changed), use [onFocusEvent] instead. |
| */ |
| @Suppress("ModifierInspectorInfo") |
| fun Modifier.onFocusChanged(onFocusChanged: (FocusState) -> Unit): Modifier = this.then( |
| @OptIn(ExperimentalComposeUiApi::class) |
| modifierElementOf( |
| key = onFocusChanged, |
| create = { FocusChangedModifierNode(onFocusChanged) }, |
| update = { it.onFocusChanged = onFocusChanged }, |
| definitions = { |
| name = "onFocusChanged" |
| properties["onFocusChanged"] = onFocusChanged |
| } |
| ) |
| ) |
| |
| @ExperimentalComposeUiApi |
| private class FocusChangedModifierNode( |
| var onFocusChanged: (FocusState) -> Unit |
| ) : FocusEventModifierNode, Modifier.Node() { |
| var focusState: FocusState? = null |
| override fun onFocusEvent(focusState: FocusState) { |
| if (this.focusState != focusState) { |
| this.focusState = focusState |
| this.onFocusChanged.invoke(focusState) |
| } |
| } |
| } |