xref: /developers/samples/android/ui/text/TextStyling-Kotlin

Text Styling
============
This sample shows how to style text on Android using spans, in Kotlin, using [Android KTX](https://github.com/android/android-ktx).

Introduction
------------
## Features
Parse some hardcoded text and do the following:
* Paragraphs starting with >  are transformed into quotes.
* Text enclosed in ``` will be transformed into inline code block.
* Lines starting with +  or *  will be transformed into bullet points.
To update the text, modify the value of `R.string.display_text`.
This project is not meant to fully cover the markdown capabilities and has several limitations; for example, quotes do not support nesting other elements.

## Implementation
The text is parsed in the [`Parser.parse`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/parser/Parser.kt#L42) method and the spans are created in the [`MarkdownBuilder.markdownToSpans`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/renderer/MarkdownBuilder.kt#L43) method.
To see how to apply one or multiple spans on a string, check out [`MarkdownBuilder.buildElement`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/renderer/MarkdownBuilder.kt#L53). For examples of creating custom spans, see [`BulletPointSpan`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/renderer/spans/BulletPointSpan.kt), [`CodeBlockSpan`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/renderer/spans/CodeBlockSpan.kt) or [`FontSpan`](https://github.com/googlesamples/android-text/blob/master/TextStyling-Kotlin/app/src/main/java/com/android/example/text/styling/renderer/spans/FontSpan.kt).

## Testing
Text parsing is tested with JUnit tests in `ParserTest`. Span building is tested via Android JUnit tests, in `MarkdownBuilderTest`.


Getting Started
---------------

Clone this repository, enter the top level directory and run `./gradlew tasks`
to get an overview of all the tasks available for this project.

Some important tasks are:

```
assembleDebug - Assembles all Debug builds.
installDebug - Installs the Debug build.
connectedAndroidTest - Installs and runs the tests for Debug build on connected
devices.
test - Run all unit tests.
```

Screenshots
-----------
<img src="../screenshots/main_activity.png" width="30%" />

Support
-------
- Stack Overflow: http://stackoverflow.com/questions/tagged/android-text

If you've found an error in this sample, please file an issue:
https://github.com/googlesamples/android-text/issues

Patches are encouraged, and may be submitted by forking this project and
submitting a pull request through GitHub.

License
--------
```
Copyright 2018 The Android Open Source Project

Licensed to the Apache Software Foundation (ASF) under one or more contributor
license agreements. See the NOTICE file distributed with this work for
additional information regarding copyright ownership. The ASF licenses this
file to you 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.
```