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# HTML Converter for Compose Multiplatform | ||
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This library provides a simple API to convert HTML to Compose's [AnnotatedString](https://developer.android.com/reference/kotlin/androidx/compose/ui/text/AnnotatedString), including styling and paragraphs. | ||
It can also be used to convert HTML to unstyled text. | ||
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It can be considered as a multiplatform replacement for Android's [`Html.fromHtml()`](https://developer.android.com/reference/android/text/Html#fromHtml(java.lang.String,%20int)) API with support for more tags and better performance. | ||
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| Platform | Supported | | ||
|---------------|----------| | ||
| Android | ✅ | | ||
| Desktop (JVM) | ✅ | | ||
| iOS | ❌ | | ||
| Web | ❌ | | ||
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The iOS platform is not yet supported: testers and contributors are welcome. | ||
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The Web platform should use the [DOM wrapper API](https://kotlinlang.org/api/latest/jvm/stdlib/org.w3c.dom/) to insert HTML directly in the web page. | ||
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## Download | ||
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[![Maven Central](https://img.shields.io/maven-central/v/be.digitalia.compose.htmlconverter/htmlconverter)](https://central.sonatype.com/search?q=g:be.digitalia.compose.htmlconverter) | ||
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Add the dependency to your **module**'s `build.gradle` or `build.gradle.kts` file: | ||
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```kotlin | ||
dependencies { | ||
implementation("be.digitalia.compose.htmlconverter:htmlconverter:0.8.0") | ||
} | ||
``` | ||
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For Kotlin Multiplatform projects: | ||
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```kotlin | ||
sourceSets { | ||
val commonMain by getting { | ||
dependencies { | ||
implementation("be.digitalia.compose.htmlconverter:htmlconverter:0.8.0") | ||
} | ||
} | ||
} | ||
``` | ||
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## Usage | ||
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To display styled HTML in a Text composable: | ||
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```kotlin | ||
Text( | ||
text = htmlToAnnotatedString(html), | ||
modifier = Modifier.fillMaxWidth() | ||
) | ||
``` | ||
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To convert HTML to unstyled text: | ||
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```kotlin | ||
val rawText = htmlToString(html) | ||
``` | ||
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Both functions take an optional `compactMode` boolean argument. When set to `true`, all paragraphs will be separated by a single line break instead of two, as it is normally the case for the tags: `p`, `blockquote`, `pre`, `ul`, `ol`, `dl`, `h1`, `h2`, `h3`, `h4`, `h5`, `h6`. The default value is `false`. | ||
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### Handling hyperlink clicks | ||
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Hyperlinks (inside the `a` tags) will be underlined and annotated with the experimental [`UrlAnnotation`](https://developer.android.com/reference/kotlin/androidx/compose/ui/text/UrlAnnotation). It is required to add custom code to detect clicks on these annotations and handle the navigation action accordingly. | ||
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For example, the `ClickableText` composable can be used, even if that solution is not perfect because it captures all touch events: | ||
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```kotlin | ||
val annotatedString = htmlToAnnotatedString(html) | ||
ClickableText( | ||
text = annotatedString, | ||
modifier = Modifier.fillMaxWidth(), | ||
onClick = { position -> | ||
annotatedString | ||
.getUrlAnnotations(position, position) | ||
.firstOrNull()?.let { range -> onLinkClick(range.item.url) } | ||
} | ||
) | ||
``` | ||
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### Custom parsing | ||
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The `htmlToAnnotatedString()` and `htmlToString()` functions provide an overload that accepts an `HTMLParser` first argument in place of a `String`. | ||
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`HTMLParser` is an interface that you may implement to provide your own parser, in case the HTML is not directly available as a `String` (for example as a character stream or encoded using a binary format). | ||
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The default implementation uses the [KtXml](https://github.com/kobjects/ktxml) multiplatform XML parser library combined with extra code to handle HTML entities and invalid HTML. | ||
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## Supported HTML tags | ||
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- Inline tags with styling: `strong`, `b` (**bold**), `em`, `cite`, `dfn`, `i` (*italic*), `big` (bigger text), `small` (smaller text), `tt`, `code` (`monospace font`), `a` ([hyperlink](#supported-html-tags)), `u` (underline), `del`, `s`, `strike` (~~strikethrough~~), `sup` (<sup>supertext</sup>), `sub` (<sub>subtext</sub>) | ||
- Block tags (paragraphs): `p`, `blockquote`, `pre` (including `monospace font`), `div`, `header`, `footer`, `main`, `nav`, `aside`, `section`, `article`, `address`, `figure`, `figcaption`, `video`, `audio` (no player shown, only inline text) | ||
- Lists: `ul`, `ol` (entries are currently unnumbered, similar to `ul`), `li`, `dl`, `dt`, `dd` | ||
- Section headings: `h1`, `h2`, `h3`, `h4`, `h5`, `h6` | ||
- Line break: `br` | ||
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The following tags are skipped, along with their content: `script`, `head`, `table`, `form`, `fieldset`. | ||
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Others tags are ignored and replaced by their content, if any. For example, an `img` tag with inline replacement text will show the replacement text. | ||
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All HTML entities appearing in the text will be properly decoded as well. | ||
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## Used libraries | ||
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* [Compose Multiplatform](https://www.jetbrains.com/lp/compose-multiplatform/) by JetBrains s.r.o. | ||
* [KtXml](https://github.com/kobjects/ktxml) by Stefan Haustein | ||
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## What to expect from future versions | ||
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- Unit tests | ||
- Proper support for ordered lists | ||
- Better clickable hyperlinks support | ||
- Support for displaying images as inline content | ||
- iOS support (with help from the community). | ||
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## License | ||
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``` | ||
Copyright (C) 2023 Christophe Beyls | ||
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 | ||
https://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. | ||
``` |