Focusable.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.foundation

import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.onCommit
import androidx.compose.runtime.onDispose
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.composed
import androidx.compose.ui.focus
import androidx.compose.ui.focus.ExperimentalFocus
import androidx.compose.ui.focus.isFocused
import androidx.compose.ui.focusObserver
import androidx.compose.ui.platform.debugInspectorInfo
import androidx.compose.ui.semantics.focused
import androidx.compose.ui.semantics.semantics

/**
 * Configure component to be focusable via focus system or accessibility "focus" event.
 *
 * Add this modifier to the element to make it focusable within its bounds.
 *
 * @sample androidx.compose.foundation.samples.FocusableSample
 *
 * @param enabled Controls the enabled state. When `false`, element won't participate in the focus
 * @param interactionState [InteractionState] that will be updated to contain [Interaction.Focused]
 * when this focusable is focused
 */
@OptIn(ExperimentalFocus::class)
fun Modifier.focusable(
    enabled: Boolean = true,
    interactionState: InteractionState? = null,
) = composed(
    inspectorInfo = debugInspectorInfo {
        name = "focusable"
        properties["enabled"] = enabled
        properties["interactionState"] = interactionState
    }
) {
    var isFocused by remember { mutableStateOf(false) }
    onDispose {
        interactionState?.removeInteraction(Interaction.Focused)
    }
    onCommit(enabled) {
        if (!enabled) {
            interactionState?.removeInteraction(Interaction.Focused)
        }
    }

    if (enabled) {
        Modifier
            .semantics {
                this.focused = isFocused
            }
            .focusObserver {
                isFocused = it.isFocused
                if (isFocused) {
                    interactionState?.addInteraction(Interaction.Focused)
                } else {
                    interactionState?.removeInteraction(Interaction.Focused)
                }
            }
            .focus()
    } else {
        Modifier
    }
}