Gestures

Overview

Ionic Gestures is a utility that allows developers to build custom gestures and interactions for their application in a platform agnostic manner. Developers do not need to be using a particular framework such as React or Angular, nor do they even need to be building an Ionic app! As long as developers have access to v5.0 or greater of Ionic Framework, they will have access to all of Ionic Animations.

Building complex gestures can be time consuming. Other libraries that provide custom gestures are often times too heavy handed and end up capturing mouse or touch events and not letting them propagate. This can result in other elements no longer being scrollable or clickable.

Installation

JavaScript

Developers using Ionic Core and JavaScript should install the latest version of @ionic/core.

import { createGesture } from 'https://cdn.jsdelivr.net/npm/@ionic/core@latest/dist/esm/index.mjs';

...

const gesture = createGesture({
  el: elementRef,
  threshold: 15,
  gestureName: 'my-gesture',
  onMove: ev => onMoveHandler(ev)
});

Angular

Developers using Ionic Core and TypeScript should install the latest version of @ionic/core.

import { createGesture, Gesture } from '@ionic/core';

...

const gesture: Gesture = createGesture({
  el: elementRef,
  threshold: 15,
  gestureName: 'my-gesture',
  onMove: ev => onMoveHandler(ev)
});

React

Developers using Angular should install the latest version of @ionic/angular. Animations can be created via the AnimationController dependency injection.

By default, gesture callbacks do not run inside of NgZone. Developers can either set the runInsideAngularZone parameter to true when creating a gesture, or they can wrap their callbacks in an NgZone.run() call.

import { Gesture, GestureController } from '@ionic/angular';

...

constructor(private gestureCtrl: GestureController) {
  const gesture: Gesture = this.gestureCtrl.create({
    el: this.element.nativeElement,
    threshold: 15,
    gestureName: 'my-gesture',
    onMove: ev => this.onMoveHandler(ev)
  }, true);
  // The `true` above ensures that callbacks run inside NgZone.
}

Vue

Developers using React should install the latest version of @ionic/react. Full React wrappers are coming soon!

import { createGesture, Gesture } from '@ionic/react';

...

const gesture: Gesture = createGesture({
  el: elementRef,
  threshold: 15,
  gestureName: 'my-gesture',
  onMove: ev => onMoveHandler(ev)
});

Developers using Ionic Vue should install the latest version of @ionic/vue.

import { createGesture } from '@ionic/vue';
import { ref } from 'vue';

...

const elementRef = ref();

...

const gesture = createGesture({
  el: elementRef.value,
  threshold: 15,
  gestureName: 'my-gesture',
  onMove: ev => onMoveHandler(ev)
});

Basic Gestures

JavaScript

let p = document.querySelector('p');
const gesture = createGesture({
  el: document.querySelector('.rectangle'),
  onMove: (detail) => { onMove(detail); }
})

gesture.enable();

const onMove = (detail) => {
  const type = detail.type;
  const currentX = detail.currentX;
  const deltaX = detail.deltaX;
  const velocityX = detail.velocityX;

  p.innerHTML = `
    <div>Type: ${type}</div>
    <div>Current X: ${currentX}</div>
    <div>Delta X: ${deltaX}</div>
    <div>Velocity X: ${velocityX}</div>
  `
}

Angular

@ViewChild('paragraph') p: ElementRef;

ngOnInit() {
  const gesture = this.gestureCtrl.create({
    el: this.rectangle.nativeElement,
    onMove: (detail) => { this.onMove(detail); }
  })

  gesture.enable();
}

private onMove(detail) {
  const type = detail.type;
  const currentX = detail.currentX;
  const deltaX = detail.deltaX;
  const velocityX = detail.velocityX;

  this.p.innerHTML = `
    <div>Type: ${type}</div>
    <div>Current X: ${currentX}</div>
    <div>Delta X: ${deltaX}</div>
    <div>Velocity X: ${velocityX}</div>
  `
}

React

let p = document.querySelector('p');
const gesture = createGesture({
  el: document.querySelector('.rectangle'),
  onMove: (detail) => { onMove(detail); }
})

gesture.enable();

const onMove = (detail) => {
  const type = detail.type;
  const currentX = detail.currentX;
  const deltaX = detail.deltaX;
  const velocityX = detail.velocityX;

  p.innerHTML = `
    <div>Type: ${type}</div>
    <div>Current X: ${currentX}</div>
    <div>Delta X: ${deltaX}</div>
    <div>Velocity X: ${velocityX}</div>
  `
}

Vue

import { createGesture } from '@ionic/vue';
import { ref } from 'vue';

...

let pRef = ref();
const rectangleRef = ref();
const gesture = createGesture({
  el: rectangleRef.value,
  onMove: (detail) => { onMove(detail); }
})

gesture.enable();

const onMove = (detail) => {
  const type = detail.type;
  const currentX = detail.currentX;
  const deltaX = detail.deltaX;
  const velocityX = detail.velocityX;

  pRef.value.innerHTML = `
    <div>Type: ${type}</div>
    <div>Current X: ${currentX}</div>
    <div>Delta X: ${deltaX}</div>
    <div>Velocity X: ${velocityX}</div>
  `
}

In this example, our app listens for gestures on the .rectangle element. When a gesture movement is detected, the onMove function is called, and our app logs the current gesture information.

Double Click Gesture

Usage

JavaScript

const backgrounds = ['rgba(0, 0, 255, 0.5)', 'rgba(0, 255, 0.5)', 'rgba(255, 0, 0, 0.5)', 'rgba(255, 255, 0, 0.5)', 'rgba(255, 0, 255, 0.5)', 'rgba(0, 255, 255, 0.5)'];
const DOUBLE_CLICK_THRESHOLD = 500;
const rectangle = document.querySelector('.rectangle');
const gesture = createGesture({
  el: rectangle,
  threshold: 0,
  onStart: () => { onStart(); }
});

gesture.enable();

let lastOnStart = 0;
let currentColor = 'rgba(0, 0, 255, 0.5)';

const onStart = () => {
  const now = Date.now();

  if (Math.abs(now - lastOnStart) <= DOUBLE_CLICK_THRESHOLD) {
    rectangle.style.setProperty('background', getRandomBackground());
    lastOnStart = 0;
  } else {
    lastOnStart = now;
  }
}

const getRandomBackground = () => {
  const options = backgrounds.filter(bg => bg !== currentColor);
  currentColor = options[Math.floor(Math.random() * options.length)];

  return currentColor;
}

Angular

@ViewChild('rectangle') rectangle: ElementRef;

private backgrounds: string[] = ['rgba(0, 0, 255, 0.5)', 'rgba(0, 255, 0.5)', 'rgba(255, 0, 0, 0.5)', 'rgba(255, 255, 0, 0.5)', 'rgba(255, 0, 255, 0.5)', 'rgba(0, 255, 255, 0.5)'];
private currentColor: string = 'rgba(0, 0, 255, 0.5)';
private lastOnStart: number = 0;
private DOUBLE_CLICK_THRESHOLD: number = 500;

ngOnInit() {
  const gesture = this.gestureCtrl.create({
    el: this.rectangle.nativeElement,
    threshold: 0,
    onStart: () => { this.onStart(); }
  });

  gesture.enable();
}

private onStart() {
  const now = Date.now();

  if (Math.abs(now - this.lastOnStart) <= this.DOUBLE_CLICK_THRESHOLD) {
    this.rectangle.nativeElement.style.setProperty('background', this.getRandomBackground());
    this.lastOnStart = 0;
  } else {
    this.lastOnStart = now;
  }
}

private getRandomBackground() {
  const options = this.backgrounds.filter(bg => bg !== this.currentColor);
  this.currentColor = options[Math.floor(Math.random() * options.length)];

  return this.currentColor;
}

React

const backgrounds = ['rgba(0, 0, 255, 0.5)', 'rgba(0, 255, 0.5)', 'rgba(255, 0, 0, 0.5)', 'rgba(255, 255, 0, 0.5)', 'rgba(255, 0, 255, 0.5)', 'rgba(0, 255, 255, 0.5)'];
const DOUBLE_CLICK_THRESHOLD = 500;
const rectangle = document.querySelector('.rectangle');
const gesture = createGesture({
  el: rectangle,
  threshold: 0,
  onStart: () => { onStart(); }
});

gesture.enable();

let lastOnStart = 0;
let currentColor = 'rgba(0, 0, 255, 0.5)';

const onStart = () => {
  const now = Date.now();

  if (Math.abs(now - lastOnStart) <= DOUBLE_CLICK_THRESHOLD) {
    rectangle.style.setProperty('background', getRandomBackground());
    lastOnStart = 0;
  } else {
    lastOnStart = now;
  }
}

const getRandomBackground = () => {
  const options = backgrounds.filter(bg => bg !== currentColor);
  currentColor = options[Math.floor(Math.random() * options.length)];

  return currentColor;
}

Vue

import { createGesture } from '@ionic/vue';
import { ref } from 'vue';

...

const backgrounds = ['rgba(0, 0, 255, 0.5)', 'rgba(0, 255, 0.5)', 'rgba(255, 0, 0, 0.5)', 'rgba(255, 255, 0, 0.5)', 'rgba(255, 0, 255, 0.5)', 'rgba(0, 255, 255, 0.5)'];
const DOUBLE_CLICK_THRESHOLD = 500;
const rectangleRef = ref();
const gesture = createGesture({
  el: rectangleRef.value,
  threshold: 0,
  onStart: () => { onStart(); }
});

gesture.enable();

let lastOnStart = 0;
let currentColor = 'rgba(0, 0, 255, 0.5)';

const onStart = () => {
  const now = Date.now();

  if (Math.abs(now - lastOnStart) <= DOUBLE_CLICK_THRESHOLD) {
    rectangleRef.value.style.setProperty('background', getRandomBackground());
    lastOnStart = 0;
  } else {
    lastOnStart = now;
  }
}

const getRandomBackground = () => {
  const options = backgrounds.filter(bg => bg !== currentColor);
  currentColor = options[Math.floor(Math.random() * options.length)];

  return currentColor;
}

In the example above, we want to be able to detect double clicks on an element. By setting our threshold to 0, we can ensure our gesture object can detect clicks. Additionally, we define a click threshold so that only 2 clicks that occur in quick succession count as a double click.

Gesture Animations

See our guide on implementing gesture animations: Gesture Animations with Ionic Animations

Types

Name	Value
GestureCallback	(detail: GestureDetail) => boolean \| void

Interfaces

GestureConfig

Property	Type	Default	Description
el	Node	undefined	The element to listen on for gestures.
disableScroll	boolean \| undefined	false	If true, scrolling will be disabled on el while the gesture is enabled.
direction	'x' \| 'y' \| undefined	'x'	Limit gesture detection to movements along a certain axis.
gestureName	string	undefined	The name of the gesture to create.
gesturePriority	number \| undefined	0	Gestures with higher priorities will override gestures with lower priorities. Useful for ensuring the multiple gestures do not collide with one another.
passive	boolean \| undefined	true	If true, this will indicate that the gesture will never call preventDefault(). This can be used to improve scrolling performance. See Passive Listeners for more information.
maxAngle	number \| undefined	40	The maximum angle to allow when detecting a gesture.
threshold	number \| undefined	10	Defines how much a pointer must move before the gesture starts.
blurOnStart	boolean \| undefined	undefined	If true, the gesture will blur any active selectable element such as an input or a textarea before firing the onStart callback.
canStart	GestureCallback \| undefined	undefined	A callback that returns true if a gesture is allowed to start.
onWillStart	(detail: GestureDetail) => Promise<void>	undefined	A callback that fires when a gesture is about to start. This is fired after canStart but before onStart.
onStart	GestureCallback \| undefined	undefined	A callback that fires when a gesture has started.
onMove	GestureCallback \| undefined	undefined	A callback that fires when a gesture movement was detected.
onEnd	GestureCallback \| undefined	undefined	A callback that fires when a gesture has ended. This is usually when a pointer has been released.
notCaptured	GestureCallback \| undefined	undefined	A callback that fires when a gesture has not been captured. This usually happens when there is a conflicting gesture with a higher priority.

GestureDetail

Property	Type	Description
type	string	The type of gesture that was detected.
startX	number	The starting x coordinate of the gesture.
startY	number	The starting y coordinate of the gesture.
startTimeStamp	number	The timestamp at which the gesture was started.
currentX	number	The current x coordinate of the gesture.
currentY	number	The current y coordinate of the gesture.
velocityX	number	How fast the gesture is currently moving on the x axis.
velocityY	number	How fast the gesture is currently moving on the y axis.
deltaX	number	How much the gesture has moved on the x axis since it started.
deltaY	number	How much the gesture has moved on the y axis since it started.
timeStamp	number	The current timestamp of the gesture.
event	UIEvent	The native event dispatched by the browser. See UIEvent for more information.
data	any \| undefined	Any data specified by the user. This can be set and read in any of the callbacks.

Methods

enable(enable: boolean = true) => void

Enable or disable the gesture.

destroy() => void

Destroy the gesture instance and stop listening on the target element.