js/controllers/touch.js
import { isAndroid } from '../utils/device.js'
import { matches } from '../utils/util.js'
const SWIPE_THRESHOLD = 40;
/**
* Controls all touch interactions and navigations for
* a presentation.
*/
export default class Touch {
constructor( Reveal ) {
this.Reveal = Reveal;
// Holds information about the currently ongoing touch interaction
this.touchStartX = 0;
this.touchStartY = 0;
this.touchStartCount = 0;
this.touchCaptured = false;
this.onPointerDown = this.onPointerDown.bind( this );
this.onPointerMove = this.onPointerMove.bind( this );
this.onPointerUp = this.onPointerUp.bind( this );
this.onTouchStart = this.onTouchStart.bind( this );
this.onTouchMove = this.onTouchMove.bind( this );
this.onTouchEnd = this.onTouchEnd.bind( this );
}
/**
*
*/
bind() {
let revealElement = this.Reveal.getRevealElement();
if( 'onpointerdown' in window ) {
// Use W3C pointer events
revealElement.addEventListener( 'pointerdown', this.onPointerDown, false );
revealElement.addEventListener( 'pointermove', this.onPointerMove, false );
revealElement.addEventListener( 'pointerup', this.onPointerUp, false );
}
else if( window.navigator.msPointerEnabled ) {
// IE 10 uses prefixed version of pointer events
revealElement.addEventListener( 'MSPointerDown', this.onPointerDown, false );
revealElement.addEventListener( 'MSPointerMove', this.onPointerMove, false );
revealElement.addEventListener( 'MSPointerUp', this.onPointerUp, false );
}
else {
// Fall back to touch events
revealElement.addEventListener( 'touchstart', this.onTouchStart, false );
revealElement.addEventListener( 'touchmove', this.onTouchMove, false );
revealElement.addEventListener( 'touchend', this.onTouchEnd, false );
}
}
/**
*
*/
unbind() {
let revealElement = this.Reveal.getRevealElement();
revealElement.removeEventListener( 'pointerdown', this.onPointerDown, false );
revealElement.removeEventListener( 'pointermove', this.onPointerMove, false );
revealElement.removeEventListener( 'pointerup', this.onPointerUp, false );
revealElement.removeEventListener( 'MSPointerDown', this.onPointerDown, false );
revealElement.removeEventListener( 'MSPointerMove', this.onPointerMove, false );
revealElement.removeEventListener( 'MSPointerUp', this.onPointerUp, false );
revealElement.removeEventListener( 'touchstart', this.onTouchStart, false );
revealElement.removeEventListener( 'touchmove', this.onTouchMove, false );
revealElement.removeEventListener( 'touchend', this.onTouchEnd, false );
}
/**
* Checks if the target element prevents the triggering of
* swipe navigation.
*/
isSwipePrevented( target ) {
// Prevent accidental swipes when scrubbing timelines
if( matches( target, 'video[controls], audio[controls]' ) ) return true;
while( target && typeof target.hasAttribute === 'function' ) {
if( target.hasAttribute( 'data-prevent-swipe' ) ) return true;
target = target.parentNode;
}
return false;
}
/**
* Handler for the 'touchstart' event, enables support for
* swipe and pinch gestures.
*
* @param {object} event
*/
onTouchStart( event ) {
this.touchCaptured = false;
if( this.isSwipePrevented( event.target ) ) return true;
this.touchStartX = event.touches[0].clientX;
this.touchStartY = event.touches[0].clientY;
this.touchStartCount = event.touches.length;
}
/**
* Handler for the 'touchmove' event.
*
* @param {object} event
*/
onTouchMove( event ) {
if( this.isSwipePrevented( event.target ) ) return true;
let config = this.Reveal.getConfig();
// Each touch should only trigger one action
if( !this.touchCaptured ) {
this.Reveal.onUserInput( event );
let currentX = event.touches[0].clientX;
let currentY = event.touches[0].clientY;
// There was only one touch point, look for a swipe
if( event.touches.length === 1 && this.touchStartCount !== 2 ) {
let availableRoutes = this.Reveal.availableRoutes({ includeFragments: true });
let deltaX = currentX - this.touchStartX,
deltaY = currentY - this.touchStartY;
if( deltaX > SWIPE_THRESHOLD && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
this.touchCaptured = true;
if( config.navigationMode === 'linear' ) {
if( config.rtl ) {
this.Reveal.next();
}
else {
this.Reveal.prev();
}
}
else {
this.Reveal.left();
}
}
else if( deltaX < -SWIPE_THRESHOLD && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
this.touchCaptured = true;
if( config.navigationMode === 'linear' ) {
if( config.rtl ) {
this.Reveal.prev();
}
else {
this.Reveal.next();
}
}
else {
this.Reveal.right();
}
}
else if( deltaY > SWIPE_THRESHOLD && availableRoutes.up ) {
this.touchCaptured = true;
if( config.navigationMode === 'linear' ) {
this.Reveal.prev();
}
else {
this.Reveal.up();
}
}
else if( deltaY < -SWIPE_THRESHOLD && availableRoutes.down ) {
this.touchCaptured = true;
if( config.navigationMode === 'linear' ) {
this.Reveal.next();
}
else {
this.Reveal.down();
}
}
// If we're embedded, only block touch events if they have
// triggered an action
if( config.embedded ) {
if( this.touchCaptured || this.Reveal.isVerticalSlide() ) {
event.preventDefault();
}
}
// Not embedded? Block them all to avoid needless tossing
// around of the viewport in iOS
else {
event.preventDefault();
}
}
}
// There's a bug with swiping on some Android devices unless
// the default action is always prevented
else if( isAndroid ) {
event.preventDefault();
}
}
/**
* Handler for the 'touchend' event.
*
* @param {object} event
*/
onTouchEnd( event ) {
this.touchCaptured = false;
}
/**
* Convert pointer down to touch start.
*
* @param {object} event
*/
onPointerDown( event ) {
if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" ) {
event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
this.onTouchStart( event );
}
}
/**
* Convert pointer move to touch move.
*
* @param {object} event
*/
onPointerMove( event ) {
if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" ) {
event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
this.onTouchMove( event );
}
}
/**
* Convert pointer up to touch end.
*
* @param {object} event
*/
onPointerUp( event ) {
if( event.pointerType === event.MSPOINTER_TYPE_TOUCH || event.pointerType === "touch" ) {
event.touches = [{ clientX: event.clientX, clientY: event.clientY }];
this.onTouchEnd( event );
}
}
}