Justified

Additional

Language
Java
Version
N/A
Created
May 7, 2014
Updated
Apr 5, 2017 (Retired)
Owner
DAVID, Jerome (programingjd)
Contributor
DAVID, Jerome (programingjd)
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Justified TextView and EditText

Android TextView or EditText with justified text for API >= 10 (Gingerbread and newer).

Usage

Use an instance of the class JustifiedTextView for a TextView with justified text.

Use an instance of the class JustifiedEditText for an EditText with justified text (the text can be editable).

Project Setup

Maven:

<dependency>
  <groupId>com.uncopt</groupId>
  <artifactId>android.justified</artifactId>
  <version>1.0</version>
</dependency>

Gradle:

dependencies {
    compile 'com.uncopt:android.justified:1.0'
}

Sample Application

[] (http://play.google.com/store/apps/details?id=com.uncopt.android.example.justify)

The source code for the demo application is in this repository (app folder).

Implementation Details

The best way to implement justification on TextViews would be to extend the Layouts from the android.text.Layout package. However those Layout classes cannot be extended easily without relying heavily on java reflection.

The next best thing is probably to add spacing spans to the text. This is what this library is doing.

The text is parsed and measured and spans are added on the whitespace between words to make the lines stretch the full width as much as possible. Those spans are very similar to ScaleXSpan, but they do not implement ParcelableSpan and are not copied by Copy or Cut and Paste operations.

The re-parsing of the text is triggered by:

  • a change of the text content.
  • a re-layout with a different width.
  • a change in the typeface, text size or text scaleX.

Some special characters are not stretched (unless there are more than one in row):

  • thin space
  • hair space
  • non breaking space

Indentation spaces are also left as-is to preserve the alignment.

The lines that do not have any whitespace or that would require the whitespace to be stretched too much are not justified. The limit for how much stretching is allowed is a factor of 10 by default, but this default can be changed.

The measuring of the text is not completely accurate (due to floating errors, font hinting, ...) and as a result, the justification is not perfect and lines can be a few pixels too short.

Screenshot

Author

Jerome DAVID - UNCOPT LLC

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License

Copyright 2013 UNCOPT LLC.

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.