rstream-gestures

This project is part of the @thi.ng/umbrella monorepo.

• About
  • Status
  • Breaking changes
• Installation
• Dependencies
• Usage examples
• API
  • GestureType
  • GestureEvent
  • GestureStreamOpts
  • Basic usage
• Authors
  • Maintainer
  • Contributors
• License

About

Unified mouse, mouse wheel & multi-touch event stream abstraction. This is a support package for @thi.ng/rstream.

Status

STABLE - used in production

Search or submit any issues for this package

Breaking changes

Multi-touch support has been added in v2.0.0, resulting in a complete rewrite of gestureStream() and new event data formats.

Installation

yarn add @thi.ng/rstream-gestures

// ES module
<script type="module" src="https://unpkg.com/@thi.ng/rstream-gestures?module" crossorigin></script>

// UMD
<script src="https://unpkg.com/@thi.ng/rstream-gestures/lib/index.umd.js" crossorigin></script>

Package sizes (gzipped, pre-treeshake): ESM: 1.18 KB / CJS: 1.24 KB / UMD: 1.30 KB

Dependencies

• @thi.ng/api
• @thi.ng/checks
• @thi.ng/math
• @thi.ng/rstream
• @thi.ng/transducers

Usage examples

Several demos in this repo's /examples directory are using this package.

A selection:

Screenshot	Description	Live demo	Source
	Canvas based dial widget	Demo	Source
	Interactive visualization of closest points on ellipses	Demo	Source
	Doodle w/ K-nearest neighbor search result visualization	Demo	Source
	Mouse gesture / stroke analysis, simplification, corner detection	Demo	Source
	Interactive pattern drawing demo using transducers	Demo	Source
	Canvas based Immediate Mode GUI components	Demo	Source
	Minimal IMGUI usage example	Demo	Source
	Worker based, interactive Mandelbrot visualization	Demo	Source
	Basic rstream-gestures multi-touch demo	Demo	Source
	Minimal shader graph developed during livestream #2	Demo	Source

API

Generated API docs

GestureType

All native events are abstracted into one of the following event types:

• move - movemove
• start - mousedown / touchstart
• drag - mousemove (whilst dragging) / touchmove
• end - mouseup / touchend / touchcancel
• zoom - wheel

GestureEvent

The stream emits GestureEvent objects of:

• type - Current translated/abstracted event type (GestureType)
• event - Original DOM event
• pos - Event position (transformed as per GestureStreamOpts)
• active - Active cursors (i.e. ongoing drag / touch gestures)
• buttons - Mouse button bitmask (same as in standard MouseEvent), or, if isTouch is true, number of active touches.
• zoom - Current zoom factor (as per GestureStreamOpts config)
• zoomDelta - Last WheelEvent's transformed deltaY, wheelDeltaY
• isTouch - True, if original event was a TouchEvent

// example mouse gesture event
{
  "type": "drag"
  "event": MouseEvent,
  "pos": [254, 169],
  "active": [
    {
      "id": 0, // always 0 for mouse gestures
      "start": [443, 37],
      "pos": [254, 169],
      "delta": [-189, 132]
    }
  ],
  "buttons": 2, // right button pressed
  "zoom": 1,
  "zoomDelta": 0,
  "isTouch": false
}

GestureStreamOpts

See the GestureStreamOpts config options for further details.

Basic usage

import { gestureStream } from "@thi.ng/rstream-gestures";
import { trace } from "@thi.ng/rstream";
import { comp, dedupe, filter, map, pluck } from "@thi.ng/transducers";

// create event stream with custom options
const gestures = gestureStream(document.body, { smooth: 0.01 });

// subscription logging zoom value changes
gestures.subscribe(
    // trace is simply logging received values to console
    trace("zoom"),
    // composed transducer, `dedupe` ensures only changed values are received
    comp(pluck("zoom"), dedupe())
);

// another subscription computing & logging drag gesture distance(s)
gestures.subscribe(
    trace("distance"),
    comp(
        filter((e) => e.type === "drag"),
        map((e) => e.active.map((g) => Math.hypot(...g.delta)))
    )
);

Authors

Maintainer

• Karsten Schmidt (@postspectacular)

Contributors

• Arthur Carabott (@acarabott)
• Matei Adriel (@Mateiadrielrafael)

If this project contributes to an academic publication, please cite it as:

@misc{thing-rstream-gestures,
  title = "@thi.ng/rstream-gestures",
  author = "Karsten Schmidt and others",
  note = "https://thi.ng/rstream-gestures",
  year = 2018
}

License

© 2018 - 2021 Karsten Schmidt // Apache Software License 2.0