Android Jetpack Compose：如何显示字符串资源中的样式文本

Question

我的 strings.xml 中有一个字符串，它针对不同的语言进行了本地化。每个本地化的字符串都带有 Html 标签。

使用 Android TextView，我能够通过读取字符串资源很好地显示样式文本。

考虑到 Jetpack Compose 目前 (1.0.0-rc02) 不支持 Html 标签，我尝试在 AndroidView 可组合项中使用 TextView，遵循官方文档：https://developer.android.com/jetpack/compose/interop/interop-apis#views-in-compose

我尝试过的示例：

@Composable
fun StyledText(text: String, modifier: Modifier = Modifier) {
    AndroidView(
            modifier = modifier,
            factory = { context -> TextView(context) },
            update = {
                it.text = HtmlCompat.fromHtml(html, HtmlCompat.FROM_HTML_MODE_COMPACT)
            }
    )
}

strings.xml 文件中的文本：

<string name="styled_text">Sample text with <b>bold styling</b> to test</string>

但是，使用 stringResource(id = R.string.styled_text) 提供的文本没有 Html 标签。

有没有办法在 Jetpack Compose 中以 Html 样式显示来自字符串资源的文本？

下面两个问题类似，但是没有从资源中读取字符串：

Android Compose: How to use HTML tags in a Text view

Answer 1

stringResource 在后台使用 resources.getString，它会丢弃任何样式信息。您需要创建类似 textResource 的内容来获取原始值：

@Composable
@ReadOnlyComposable
fun textResource(@StringRes id: Int): CharSequence =
    LocalContext.current.resources.getText(id)

并像这样使用它：

StyledText(textResource(id = R.string.foo))

@Composable
fun StyledText(text: CharSequence, modifier: Modifier = Modifier) {
    AndroidView(
        modifier = modifier,
        factory = { context -> TextView(context) },
        update = {
            it.text = text
        }
    )
}

Answer 2

目前，您可以使用 AnnotatedString class 在 Text 组件中显示样式文本。我将向您展示一个示例：

Text(
    text = buildAnnotatedString {
        withStyle(style = SpanStyle(fontWeight = FontWeight.Thin)) {
            append(stringResource(id = R.string.thin_string))
        }
        withStyle(style = SpanStyle(fontWeight = FontWeight.Bold)) {
            append(stringResource(id = R.string.bold_string))
        }
    },
)

根据您指定的样式，您将获得带有红色突出显示样式的文本

https://i.stack.imgur.com/XSMMB.png

更多信息：https://developer.android.com/jetpack/compose/text?hl=nl#multiple-styles

Answer 3

正在讨论如何在 Jetpack Compose 上实施 UI： https://issuetracker.google.com/issues/139320238

经过一番研究，我想出了以下解决方案，我也在同一讨论中发布了该解决方案：

@Composable
@ReadOnlyComposable
private fun resources(): Resources {
    LocalConfiguration.current
    return LocalContext.current.resources
}

fun Spanned.toHtmlWithoutParagraphs(): String {
    return HtmlCompat.toHtml(this, HtmlCompat.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE)
        .substringAfter("<p dir=\"ltr\">").substringBeforeLast("</p>")
}

fun Resources.getText(@StringRes id: Int, vararg args: Any): CharSequence {
    val escapedArgs = args.map {
        if (it is Spanned) it.toHtmlWithoutParagraphs() else it
    }.toTypedArray()
    val resource = SpannedString(getText(id))
    val htmlResource = resource.toHtmlWithoutParagraphs()
    val formattedHtml = String.format(htmlResource, *escapedArgs)
    return HtmlCompat.fromHtml(formattedHtml, HtmlCompat.FROM_HTML_MODE_LEGACY)
}

@Composable
fun annotatedStringResource(@StringRes id: Int, vararg formatArgs: Any): AnnotatedString {
    val resources = resources()
    val density = LocalDensity.current
    return remember(id, formatArgs) {
        val text = resources.getText(id, *formatArgs)
        spannableStringToAnnotatedString(text, density)
    }
}

@Composable
fun annotatedStringResource(@StringRes id: Int): AnnotatedString {
    val resources = resources()
    val density = LocalDensity.current
    return remember(id) {
        val text = resources.getText(id)
        spannableStringToAnnotatedString(text, density)
    }
}

private fun spannableStringToAnnotatedString(
    text: CharSequence,
    density: Density
): AnnotatedString {
    return if (text is Spanned) {
        with(density) {
            buildAnnotatedString {
                append((text.toString()))
                text.getSpans(0, text.length, Any::class.java).forEach {
                    val start = text.getSpanStart(it)
                    val end = text.getSpanEnd(it)
                    when (it) {
                        is StyleSpan -> when (it.style) {
                            Typeface.NORMAL -> addStyle(
                                SpanStyle(
                                    fontWeight = FontWeight.Normal,
                                    fontStyle = FontStyle.Normal
                                ),
                                start,
                                end
                            )
                            Typeface.BOLD -> addStyle(
                                SpanStyle(
                                    fontWeight = FontWeight.Bold,
                                    fontStyle = FontStyle.Normal
                                ),
                                start,
                                end
                            )
                            Typeface.ITALIC -> addStyle(
                                SpanStyle(
                                    fontWeight = FontWeight.Normal,
                                    fontStyle = FontStyle.Italic
                                ),
                                start,
                                end
                            )
                            Typeface.BOLD_ITALIC -> addStyle(
                                SpanStyle(
                                    fontWeight = FontWeight.Bold,
                                    fontStyle = FontStyle.Italic
                                ),
                                start,
                                end
                            )
                        }
                        is TypefaceSpan -> addStyle(
                            SpanStyle(
                                fontFamily = when (it.family) {
                                    FontFamily.SansSerif.name -> FontFamily.SansSerif
                                    FontFamily.Serif.name -> FontFamily.Serif
                                    FontFamily.Monospace.name -> FontFamily.Monospace
                                    FontFamily.Cursive.name -> FontFamily.Cursive
                                    else -> FontFamily.Default
                                }
                            ),
                            start,
                            end
                        )
                        is BulletSpan -> {
                            Log.d("StringResources", "BulletSpan not supported yet")
                            addStyle(SpanStyle(), start, end)
                        }
                        is AbsoluteSizeSpan -> addStyle(
                            SpanStyle(fontSize = if (it.dip) it.size.dp.toSp() else it.size.toSp()),
                            start,
                            end
                        )
                        is RelativeSizeSpan -> addStyle(
                            SpanStyle(fontSize = it.sizeChange.em),
                            start,
                            end
                        )
                        is StrikethroughSpan -> addStyle(
                            SpanStyle(textDecoration = TextDecoration.LineThrough),
                            start,
                            end
                        )
                        is UnderlineSpan -> addStyle(
                            SpanStyle(textDecoration = TextDecoration.Underline),
                            start,
                            end
                        )
                        is SuperscriptSpan -> addStyle(
                            SpanStyle(baselineShift = BaselineShift.Superscript),
                            start,
                            end
                        )
                        is SubscriptSpan -> addStyle(
                            SpanStyle(baselineShift = BaselineShift.Subscript),
                            start,
                            end
                        )
                        is ForegroundColorSpan -> addStyle(
                            SpanStyle(color = Color(it.foregroundColor)),
                            start,
                            end
                        )
                        else -> addStyle(SpanStyle(), start, end)
                    }
                }
            }
        }
    } else {
        AnnotatedString(text.toString())
    }
}

来源：https://issuetracker.google.com/issues/139320238#comment11

使用这些辅助方法，您只需调用：

Text(annotatedStringResource(R.string.your_string_resource))

Android Jetpack Compose：如何显示字符串资源中的样式文本

Android Jetpack Compose: How to show styled Text from string resources

android

kotlin

android-jetpack-compose

android-jetpack-compose-text