skikoMain.androidx.compose.ui.text.platform.SkiaParagraphIntrinsics.skiko.kt Maven / Gradle / Ivy

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/*
 * Copyright 2023 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.text.platform

import androidx.compose.ui.text.*
import androidx.compose.ui.text.AnnotatedString.Range
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.intl.Locale
import androidx.compose.ui.text.intl.LocaleList
import androidx.compose.ui.text.intl.isRtl
import androidx.compose.ui.text.style.ResolvedTextDirection
import androidx.compose.ui.text.style.TextDirection
import androidx.compose.ui.unit.Density
import kotlin.math.ceil

internal actual fun ActualParagraphIntrinsics(
    text: String,
    style: TextStyle,
    spanStyles: List>,
    placeholders: List>,
    density: Density,
    fontFamilyResolver: FontFamily.Resolver
): ParagraphIntrinsics =
    SkiaParagraphIntrinsics(
        text,
        style,
        spanStyles,
        placeholders,
        density,
        fontFamilyResolver
    )

internal class SkiaParagraphIntrinsics(
    val text: String,
    private val style: TextStyle,
    private val spanStyles: List>,
    private val placeholders: List>,
    private val density: Density,
    private val fontFamilyResolver: FontFamily.Resolver
) : ParagraphIntrinsics {
    val textDirection = resolveTextDirection(text, style.textDirection, style.localeList)

    private var layouter: ParagraphLayouter? = newLayouter()

    fun layouter(): ParagraphLayouter {
        val layouter = this.layouter ?: newLayouter()
        this.layouter = null
        return layouter
    }

    private fun newLayouter() = ParagraphLayouter(
        text = text,
        textDirection = textDirection,
        style = style,
        spanStyles = spanStyles,
        placeholders = placeholders,
        density = density,
        fontFamilyResolver = fontFamilyResolver
    )

    override var minIntrinsicWidth = 0f
        private set
    override var maxIntrinsicWidth = 0f
        private set

    init {
        val para = layouter!!.layoutParagraph(Float.POSITIVE_INFINITY)
        minIntrinsicWidth = ceil(para.minIntrinsicWidth)
        maxIntrinsicWidth = ceil(para.maxIntrinsicWidth)
    }
}

internal fun resolveTextDirection(
    text: String,
    textDirection: TextDirection? = null,
    localeList: LocaleList? = null
): ResolvedTextDirection {
    return when (textDirection ?: TextDirection.Content) {
        TextDirection.Ltr -> ResolvedTextDirection.Ltr
        TextDirection.Rtl -> ResolvedTextDirection.Rtl
        TextDirection.Content -> contentBasedTextDirection(text) { localeBasedTextDirection(localeList?.firstOrNull()) }
        TextDirection.ContentOrLtr -> contentBasedTextDirection(text) { ResolvedTextDirection.Ltr }
        TextDirection.ContentOrRtl -> contentBasedTextDirection(text) { ResolvedTextDirection.Rtl }
        else -> error("Invalid TextDirection.")
    }
}

/**
 * Determine the paragraph direction by the first strong directional character. If no strong
 * character is found, fallback() will be called.
 *
 * This is the standard Unicode Bidirectional Algorithm (steps P2 and P3).
 * See https://www.unicode.org/reports/tr9/
 */
private fun contentBasedTextDirection(text: String, fallback: () -> ResolvedTextDirection) =
    when (text.firstStrongDirectionType()) {
        StrongDirectionType.Ltr -> ResolvedTextDirection.Ltr
        StrongDirectionType.Rtl -> ResolvedTextDirection.Rtl
        else -> fallback()
    }

private fun localeBasedTextDirection(locale: Locale?) =
    if ((locale ?: Locale.current).platformLocale.isRtl()) {
        ResolvedTextDirection.Rtl
    } else {
        ResolvedTextDirection.Ltr
    }