FocusModifier.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.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.composed
import androidx.compose.ui.focus.FocusStateImpl.Inactive
import androidx.compose.ui.node.ModifiedFocusNode
import androidx.compose.ui.platform.InspectorInfo
import androidx.compose.ui.platform.InspectorValueInfo
import androidx.compose.ui.platform.NoInspectorInfo
import androidx.compose.ui.platform.debugInspectorInfo
/**
* A [Modifier.Element] that wraps makes the modifiers on the right into a Focusable. Use a
* different instance of [FocusModifier] for each focusable component.
*/
internal class FocusModifier(
initialFocus: FocusStateImpl,
// TODO(b/172265016): Make this a required parameter and remove the default value.
// Set this value in AndroidComposeView, and other places where we create a focus modifier
// using this internal constructor.
inspectorInfo: InspectorInfo.() -> Unit = NoInspectorInfo
) : Modifier.Element, InspectorValueInfo(inspectorInfo) {
// TODO(b/188684110): Move focusState and focusedChild to ModiedFocusNode and make this
// modifier stateless.
var focusState: FocusStateImpl = initialFocus
var focusedChild: ModifiedFocusNode? = null
lateinit var focusNode: ModifiedFocusNode
}
/**
* Add this modifier to a component to make it focusable.
*
* Focus state is stored within this modifier. The bounds of this modifier reflect the bounds of
* the focus box.
*
* Note: This is a low level modifier. Before using this consider using
* [Modifier.focusable()][androidx.compose.foundation.focusable]. It uses a [focusTarget] in
* its implementation. [Modifier.focusable()][androidx.compose.foundation.focusable] adds semantics
* that are needed for accessibility.
*
* @sample androidx.compose.ui.samples.FocusableSampleUsingLowerLevelFocusTarget
*/
fun Modifier.focusTarget(): Modifier = composed(debugInspectorInfo { name = "focusTarget" }) {
remember { FocusModifier(Inactive) }
}
/**
* Add this modifier to a component to make it focusable.
*/
@Deprecated(
"Replaced by focusTarget",
ReplaceWith("focusTarget()", "androidx.compose.ui.focus.focusTarget")
)
fun Modifier.focusModifier(): Modifier = composed(debugInspectorInfo { name = "focusModifier" }) {
remember { FocusModifier(Inactive) }
}