benhutchison / gesture   0.5

MIT License GitHub

Purely functional recognition of Drag and Click gestures over a W3C Pointer Event -compatible API in Scala/Scala.js

Scala versions: 2.13

Gesture

Purely functional recognition of Drag and Click gestures over a W3C Pointer Event -compatible API, for Scala/Scala.js

Built on top of State provided by the Cats library.

See also slidedeck about the library design.

Gesture core

Contains the library code:

  • GestureProcessor converts a series of PointerEvents into a series of GestureEvents, while updating a Finite State Machine represented by PointerState.

  • Optionally, GestureAndRegionProcessor[R] can extend the functionality to tracking the region R where the gesture began and completed, if any. The region itself is provided by the user of the library an can be any type, so long a there is a search function (Double, Double) => Option[R] to find the region R at a coordinate, if any.

  • Coordinates are modeled as (Double, Double)

Published for both Scala.jvm and Scala.js.

SBT: "com.github.benhutchison" %%% "gesture" % "0.5"

Changelog

Version When Changes
0.1 Jan 16 Initial release
0.2 Oct 16 Upgrade libs, cats to 0.7.2, scalajs-dom to 0.9
0.3 Nov 16 Scala 2.12, cats to 0.8.1
0.4 Nov 17 SBT, cats, Scalajs, Specs upgrade. Remove Pointer Event polyfill
0.5 Feb 22 Scala, ScalaJS, Library upgrade
0.6 Feb 22 Scala 3. Better use of DOM PointerEvents. Rewrite demo code.

Gesture Demo

Shows a working demo of the recognition system, implemented over an HTML canvas. Colored rectangles can be created and dragged around the screen.

To try it out, clone the project, run sbt demo/fullOptJS, and then load file demo/demo-opt.html in a browser.