A gesture trail drawing library for Android and Java applications.

It allows to draw thick and thin strokes as if you were used a felt-tip marker. To achieve this, we first used a polygonal chain in order to approximate the hand-drawing trail and to select the most salient points. Next, we used a quadratic Bezier curve approximation to model a smooth curve in place of the original path. This smooth path serves then to guide a virtual felt-tip modeled by a flattened ellipsoid which orientation remains constant during the entire drawing. The main difficulty of this treatment is to perform it online without perceived latency.

It is a maven build, so basically mvn install should do the job. It will install the library in your local repository. You can also retrieve the jar file under the target directory (after the maven build).

The library is published on maven central to ease developers' life. So to use the library in a maven build:

<dependency>
  <groupId>com.orange.dgil.trail</groupId>
  <artifactId>trail-core-lib</artifactId>
  <version>1.2.3</version>
  <scope>compile</scope>
</dependency>

In a gradle build:

dependencies {
  compile "com.orange.dgil.trail:trail-core-lib:1.2.3"
}

Can be found in the "demo" directory: android and javafx apps. Basically the javafx application is used to test and debug algorithms. Above gestures where produced with the android "DroidTest" demo, whose prebuilt apk is here (click on "Raw" to save file): Demo apk

Both demo apps use gradle for the build.

For "DroidTest", ./gradlew assembleDebug will build the apk.

For "JavaFxTest", ./gradlew run will build and launch the application. Be sure to use oracle java 8 jvm here.

Happy testing!

Copyright (C) 2014 Orange

The trail drawing library is distributed under the terms and conditions of the Mozilla Public License v2.0, https://www.mozilla.org/MPL/2.0

The library is born in 2014 at the Orange Labs in Meylan (french Alps). If Christophe Maldivi and Eric Petit practice cliff climbing together, they also sometimes write software together :)