BasicCurvedText.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.wear.compose.foundation

import androidx.compose.foundation.layout.Box
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.drawscope.DrawScope
import androidx.compose.ui.layout.Measurable
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.semantics.contentDescription
import androidx.compose.ui.semantics.semantics
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.text.font.FontSynthesis
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.unit.Constraints
import kotlin.math.roundToInt
import kotlin.math.sqrt

/**
 * [basicCurvedText] is a component allowing developers to easily write curved text following
 * the curvature a circle (usually at the edge of a circular screen).
 * [basicCurvedText] can be only created within the [CurvedLayout] since it's not a not a
 * composable.
 *
 * @sample androidx.wear.compose.foundation.samples.CurvedAndNormalText
 *
 * @param text The text to display
 * @param modifier The [CurvedModifier] to apply to this curved text.
 * @param angularDirection Specify if the text is laid out clockwise or anti-clockwise, and if
 * those needs to be reversed in a Rtl layout.
 * If not specified, it will be inherited from the enclosing [curvedRow] or [CurvedLayout]
 * See [CurvedDirection.Angular].
 * @param overflow How visual overflow should be handled.
 * @param style A @Composable factory to provide the style to use. This composable SHOULDN'T
 * generate any compose nodes.
 */
public fun CurvedScope.basicCurvedText(
    text: String,
    modifier: CurvedModifier = CurvedModifier,
    angularDirection: CurvedDirection.Angular? = null,
    overflow: TextOverflow = TextOverflow.Clip,
    style: @Composable () -> CurvedTextStyle = { CurvedTextStyle() }
) = add(CurvedTextChild(
    text,
    curvedLayoutDirection.copy(overrideAngular = angularDirection).absoluteClockwise(),
    style,
    overflow
), modifier)

/**
 * [basicCurvedText] is a component allowing developers to easily write curved text following
 * the curvature a circle (usually at the edge of a circular screen).
 * [basicCurvedText] can be only created within the [CurvedLayout] since it's not a not a
 * composable.
 *
 * @sample androidx.wear.compose.foundation.samples.CurvedAndNormalText
 *
 * @param text The text to display
 * @param style A style to use.
 * @param modifier The [CurvedModifier] to apply to this curved text.
 * @param angularDirection Specify if the text is laid out clockwise or anti-clockwise, and if
 * those needs to be reversed in a Rtl layout.
 * If not specified, it will be inherited from the enclosing [curvedRow] or [CurvedLayout]
 * See [CurvedDirection.Angular].
 * @param overflow How visual overflow should be handled.
 */
public fun CurvedScope.basicCurvedText(
    text: String,
    style: CurvedTextStyle,
    modifier: CurvedModifier = CurvedModifier,
    angularDirection: CurvedDirection.Angular? = null,
    overflow: TextOverflow = TextOverflow.Clip,
) = basicCurvedText(text, modifier, angularDirection, overflow) { style }

internal class CurvedTextChild(
    val text: String,
    val clockwise: Boolean = true,
    val style: @Composable () -> CurvedTextStyle = { CurvedTextStyle() },
    val overflow: TextOverflow
) : CurvedChild() {
    private lateinit var delegate: CurvedTextDelegate
    private lateinit var actualStyle: CurvedTextStyle

    // We create a compose-ui node so that we can attach a11y info.
    private lateinit var placeable: Placeable

    @Composable
    override fun SubComposition() {
        actualStyle = DefaultCurvedTextStyles + style()
        // Avoid recreating the delegate if possible, as it's expensive
        delegate = remember { CurvedTextDelegate() }
        delegate.UpdateFontIfNeeded(
            actualStyle.fontFamily,
            actualStyle.fontWeight,
            actualStyle.fontStyle,
            actualStyle.fontSynthesis
        )

        // Empty compose-ui node to attach a11y info.
        Box(Modifier.semantics { contentDescription = text })
    }

    override fun CurvedMeasureScope.initializeMeasure(
        measurables: Iterator<Measurable>
    ) {
        delegate.updateIfNeeded(
            text,
            clockwise,
            actualStyle.fontSize.toPx()
        )

        // Size the compose-ui node reasonably.
        // We make the bounding rectangle sizes as the text, but cut the width (if needed) to the
        // point at which the circle crosses the middle of the side
        val height = delegate.textHeight.roundToInt()
        val maxWidth = sqrt(height * (radius - height / 4))
        val width = delegate.textWidth.coerceAtMost(maxWidth).roundToInt()

        // Measure the corresponding measurable.
        placeable = measurables.next().measure(Constraints(
            minWidth = width, maxWidth = width, minHeight = height, maxHeight = height
        ))
    }

    override fun doEstimateThickness(maxRadius: Float): Float = delegate.textHeight

    override fun doRadialPosition(
        parentOuterRadius: Float,
        parentThickness: Float
    ): PartialLayoutInfo {
        val measureRadius = parentOuterRadius - delegate.baseLinePosition
        return PartialLayoutInfo(
            delegate.textWidth / measureRadius,
            parentOuterRadius,
            delegate.textHeight,
            measureRadius
        )
    }

    private var parentSweepRadians: Float = 0f

    override fun doAngularPosition(
        parentStartAngleRadians: Float,
        parentSweepRadians: Float,
        centerOffset: Offset
    ): Float {
        this.parentSweepRadians = parentSweepRadians
        return super.doAngularPosition(parentStartAngleRadians, parentSweepRadians, centerOffset)
    }

    override fun DrawScope.draw() {
        with(delegate) {
            doDraw(
                layoutInfo!!,
                parentSweepRadians,
                overflow,
                actualStyle.color,
                actualStyle.background
            )
        }
    }

    override fun (Placeable.PlacementScope).placeIfNeeded() =
        // clockwise doesn't matter, we have no content in placeable.
        place(placeable, layoutInfo!!, parentSweepRadians, clockwise = false)
}

internal expect class CurvedTextDelegate() {
    var textWidth: Float
    var textHeight: Float
    var baseLinePosition: Float

    fun updateIfNeeded(
        text: String,
        clockwise: Boolean,
        fontSizePx: Float
    )

    @Composable
    fun UpdateFontIfNeeded(
        fontFamily: FontFamily?,
        fontWeight: FontWeight?,
        fontStyle: FontStyle?,
        fontSynthesis: FontSynthesis?
    )

    fun DrawScope.doDraw(
        layoutInfo: CurvedLayoutInfo,
        parentSweepRadians: Float,
        overflow: TextOverflow,
        color: Color,
        background: Color
    )
}