Divider.kt

/*
 * Copyright 2022 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.material3

import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.height
import androidx.compose.material3.tokens.DividerTokens
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp

// TODO: Link to M3 spec when available.
/**
 * <a href="https://material.io/components/dividers" class="external" target="_blank">Material Design divider</a>.
 *
 * A divider is a thin line that groups content in lists and layouts.
 *
 * ![Divider image](https://developer.android.com/images/reference/androidx/compose/material3/divider.png)
 *
 * @param modifier the [Modifier] to be applied to this divider line
 * @param color color of this divider line
 * @param thickness thickness of this divider line. Using [Dp.Hairline] will produce a single pixel
 * divider regardless of screen density.
 * @param startIndent start offset of this line. No offset by default.
 */
@Composable
fun Divider(
    modifier: Modifier = Modifier,
    color: Color = DividerDefaults.Color,
    thickness: Dp = DividerDefaults.Thickness,
    startIndent: Dp = 0.dp
) {
    val indentMod = if (startIndent.value != 0f) {
        Modifier.padding(start = startIndent)
    } else {
        Modifier
    }
    val targetThickness = if (thickness == Dp.Hairline) {
        (1f / LocalDensity.current.density).dp
    } else {
        thickness
    }
    Box(
        modifier.then(indentMod)
            .fillMaxWidth()
            .height(targetThickness)
            .background(color = color)
    )
}

/** Default values for [Divider] */
object DividerDefaults {
    /** Default color of a divider. */
    val Color: Color @Composable get() = DividerTokens.Color.toColor()

    /** Default thickness of a divider. */
    val Thickness: Dp = DividerTokens.Thickness
}