xref: /glance/glance/src/main/java/androidx/glance/Button.kt

/*
 * Copyright 2021 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.glance

import androidx.annotation.RestrictTo
import androidx.compose.runtime.Composable
import androidx.glance.action.Action
import androidx.glance.action.action
import androidx.glance.action.clickable
import androidx.glance.text.EmittableText
import androidx.glance.text.TextStyle
import androidx.glance.unit.ColorProvider

/**
 * Adds a button view to the glance view.
 *
 * @param text The text that this button will show.
 * @param onClick The action to be performed when this button is clicked.
 * @param modifier The modifier to be applied to this button.
 * @param enabled If false, the button will not be clickable.
 * @param style The style to be applied to the text in this button.
 * @param colors The colors to use for the background and content of the button.
 * @param maxLines An optional maximum number of lines for the text to span, wrapping if necessary.
 *   If the text exceeds the given number of lines, it will be truncated.
 */
@Composable
fun Button(
    text: String,
    onClick: Action,
    modifier: GlanceModifier = GlanceModifier,
    enabled: Boolean = true,
    style: TextStyle? = null,
    colors: ButtonColors = ButtonDefaults.buttonColors(),
    maxLines: Int = Int.MAX_VALUE,
) = ButtonElement(text, onClick, modifier, enabled, style, colors, maxLines)

/**
 * Adds a button view to the glance view.
 *
 * @param text The text that this button will show.
 * @param onClick The action to be performed when this button is clicked.
 * @param modifier The modifier to be applied to this button.
 * @param enabled If false, the button will not be clickable.
 * @param style The style to be applied to the text in this button.
 * @param colors The colors to use for the background and content of the button.
 * @param maxLines An optional maximum number of lines for the text to span, wrapping if necessary.
 *   If the text exceeds the given number of lines, it will be truncated.
 */
@Composable
fun Button(
    text: String,
    onClick: () -> Unit,
    modifier: GlanceModifier = GlanceModifier,
    enabled: Boolean = true,
    style: TextStyle? = null,
    colors: ButtonColors = ButtonDefaults.buttonColors(),
    maxLines: Int = Int.MAX_VALUE,
) = ButtonElement(text, action(block = onClick), modifier, enabled, style, colors, maxLines)

/**
 * Adds a button view to the glance view.
 *
 * @param text The text that this button will show.
 * @param onClick The action to be performed when this button is clicked.
 * @param modifier The modifier to be applied to this button.
 * @param enabled If false, the button will not be clickable.
 * @param style The style to be applied to the text in this button.
 * @param colors The colors to use for the background and content of the button.
 * @param maxLines An optional maximum number of lines for the text to span, wrapping if necessary.
 *   If the text exceeds the given number of lines, it will be truncated.
 * @param key A stable and unique key that identifies the action for this button. This ensures that
 *   the correct action is triggered, especially in cases of items that change order. If not
 *   provided we use the key that is automatically generated by the Compose runtime, which is unique
 *   for every exact code location in the composition tree.
 */
@ExperimentalGlanceApi
@Composable
fun Button(
    text: String,
    onClick: () -> Unit,
    modifier: GlanceModifier = GlanceModifier,
    enabled: Boolean = true,
    style: TextStyle? = null,
    colors: ButtonColors = ButtonDefaults.buttonColors(),
    maxLines: Int = Int.MAX_VALUE,
    key: String? = null
) = ButtonElement(text, action(key, onClick), modifier, enabled, style, colors, maxLines)

@Composable
internal fun ButtonElement(
    text: String,
    onClick: Action,
    modifier: GlanceModifier = GlanceModifier,
    enabled: Boolean = true,
    style: TextStyle? = null,
    colors: ButtonColors = ButtonDefaults.buttonColors(),
    maxLines: Int = Int.MAX_VALUE,
) {
    var finalModifier = if (enabled) modifier.clickable(onClick) else modifier
    finalModifier = finalModifier.background(colors.backgroundColor)
    val finalStyle =
        style?.copy(color = colors.contentColor) ?: TextStyle(color = colors.contentColor)

    GlanceNode(
        factory = ::EmittableButton,
        update = {
            this.set(text) { this.text = it }
            this.set(finalModifier) { this.modifier = it }
            this.set(finalStyle) { this.style = it }
            this.set(colors) { this.colors = it }
            this.set(enabled) { this.enabled = it }
            this.set(maxLines) { this.maxLines = it }
        }
    )
}

@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
class EmittableButton : EmittableWithText() {
    override var modifier: GlanceModifier = GlanceModifier
    var colors: ButtonColors? = null
    var enabled: Boolean = true

    override fun copy(): Emittable =
        EmittableButton().also {
            it.modifier = modifier
            it.text = text
            it.style = style
            it.colors = colors
            it.enabled = enabled
            it.maxLines = maxLines
        }

    override fun toString(): String =
        "EmittableButton('$text', enabled=$enabled, style=$style, " +
            "colors=$colors modifier=$modifier, maxLines=$maxLines)"
}

@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
fun EmittableButton.toEmittableText() =
    EmittableText().also {
        it.modifier = modifier
        it.text = text
        it.style = style
        it.maxLines = maxLines
    }

/** Represents the colors used to style a button, prefer this to using the modifier. */
class ButtonColors
internal constructor(val backgroundColor: ColorProvider, val contentColor: ColorProvider) {
    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (javaClass != other?.javaClass) return false

        other as ButtonColors

        if (backgroundColor != other.backgroundColor) return false
        if (contentColor != other.contentColor) return false

        return true
    }

    override fun hashCode(): Int {
        var result = backgroundColor.hashCode()
        result = 31 * result + contentColor.hashCode()
        return result
    }
}

/** Contains the default values used by [Button]. */
object ButtonDefaults {
    @Composable
    /**
     * Creates a [ButtonColors] that represents the default background and content colors used in a
     * [Button].
     *
     * @param backgroundColor the background color of this [Button]
     * @param contentColor the content color of this [Button]
     */
    fun buttonColors(
        backgroundColor: ColorProvider = GlanceTheme.colors.primary,
        contentColor: ColorProvider = GlanceTheme.colors.onPrimary
    ) = ButtonColors(backgroundColor = backgroundColor, contentColor = contentColor)
}