Extract Carousel's swipe functionality to a separate Class (#32999)

2 files changed, 142 insertions, 71 deletions

diff --git a/js/src/carousel.js b/js/src/carousel.js
index 161e980c61..f28ee259b3 100644
--- a/js/src/carousel.js
+++ b/js/src/carousel.js
@@ -8,9 +8,9 @@
 import {
   defineJQueryPlugin,
   getElementFromSelector,
+  getNextActiveElement,
   isRTL,
   isVisible,
-  getNextActiveElement,
   reflow,
   triggerTransitionEnd,
   typeCheckConfig
@@ -18,6 +18,7 @@ import {
 import EventHandler from './dom/event-handler'
 import Manipulator from './dom/manipulator'
 import SelectorEngine from './dom/selector-engine'
+import Swipe from './util/swipe'
 import BaseComponent from './base-component'
 
 /**
@@ -34,7 +35,6 @@ const DATA_API_KEY = '.data-api'
 const ARROW_LEFT_KEY = 'ArrowLeft'
 const ARROW_RIGHT_KEY = 'ArrowRight'
 const TOUCHEVENT_COMPAT_WAIT = 500 // Time for mouse compat events to fire after touch
-const SWIPE_THRESHOLD = 40
 
 const Default = {
   interval: 5000,
@@ -69,11 +69,6 @@ const EVENT_SLID = `slid${EVENT_KEY}`
 const EVENT_KEYDOWN = `keydown${EVENT_KEY}`
 const EVENT_MOUSEENTER = `mouseenter${EVENT_KEY}`
 const EVENT_MOUSELEAVE = `mouseleave${EVENT_KEY}`
-const EVENT_TOUCHSTART = `touchstart${EVENT_KEY}`
-const EVENT_TOUCHMOVE = `touchmove${EVENT_KEY}`
-const EVENT_TOUCHEND = `touchend${EVENT_KEY}`
-const EVENT_POINTERDOWN = `pointerdown${EVENT_KEY}`
-const EVENT_POINTERUP = `pointerup${EVENT_KEY}`
 const EVENT_DRAG_START = `dragstart${EVENT_KEY}`
 const EVENT_LOAD_DATA_API = `load${EVENT_KEY}${DATA_API_KEY}`
 const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
@@ -85,7 +80,6 @@ const CLASS_NAME_END = 'carousel-item-end'
 const CLASS_NAME_START = 'carousel-item-start'
 const CLASS_NAME_NEXT = 'carousel-item-next'
 const CLASS_NAME_PREV = 'carousel-item-prev'
-const CLASS_NAME_POINTER_EVENT = 'pointer-event'
 
 const SELECTOR_ACTIVE = '.active'
 const SELECTOR_ACTIVE_ITEM = '.active.carousel-item'
@@ -97,9 +91,6 @@ const SELECTOR_INDICATOR = '[data-bs-target]'
 const SELECTOR_DATA_SLIDE = '[data-bs-slide], [data-bs-slide-to]'
 const SELECTOR_DATA_RIDE = '[data-bs-ride="carousel"]'
 
-const POINTER_TYPE_TOUCH = 'touch'
-const POINTER_TYPE_PEN = 'pen'
-
 /**
  * ------------------------------------------------------------------------
  * Class Definition
@@ -115,14 +106,10 @@ class Carousel extends BaseComponent {
     this._isPaused = false
     this._isSliding = false
     this.touchTimeout = null
-    this.touchStartX = 0
-    this.touchDeltaX = 0
+    this._swipeHelper = null
 
     this._config = this._getConfig(config)
     this._indicatorsElement = SelectorEngine.findOne(SELECTOR_INDICATORS, this._element)
-    this._touchSupported = 'ontouchstart' in document.documentElement || navigator.maxTouchPoints > 0
-    this._pointerEvent = Boolean(window.PointerEvent)
-
     this._addEventListeners()
   }
 
@@ -214,6 +201,14 @@ class Carousel extends BaseComponent {
     this._slide(order, this._items[index])
   }
 
+  dispose() {
+    if (this._swipeHelper) {
+      this._swipeHelper.dispose()
+    }
+
+    super.dispose()
+  }
+
   // Private
 
   _getConfig(config) {
@@ -226,24 +221,6 @@ class Carousel extends BaseComponent {
     return config
   }
 
-  _handleSwipe() {
-    const absDeltax = Math.abs(this.touchDeltaX)
-
-    if (absDeltax <= SWIPE_THRESHOLD) {
-      return
-    }
-
-    const direction = absDeltax / this.touchDeltaX
-
-    this.touchDeltaX = 0
-
-    if (!direction) {
-      return
-    }
-
-    this._slide(direction > 0 ? DIRECTION_RIGHT : DIRECTION_LEFT)
-  }
-
   _addEventListeners() {
     if (this._config.keyboard) {
       EventHandler.on(this._element, EVENT_KEYDOWN, event => this._keydown(event))
@@ -254,38 +231,17 @@ class Carousel extends BaseComponent {
       EventHandler.on(this._element, EVENT_MOUSELEAVE, event => this.cycle(event))
     }
 
-    if (this._config.touch && this._touchSupported) {
+    if (this._config.touch && Swipe.isSupported()) {
       this._addTouchEventListeners()
     }
   }
 
   _addTouchEventListeners() {
-    const hasPointerPenTouch = event => {
-      return this._pointerEvent &&
-        (event.pointerType === POINTER_TYPE_PEN || event.pointerType === POINTER_TYPE_TOUCH)
-    }
-
-    const start = event => {
-      if (hasPointerPenTouch(event)) {
-        this.touchStartX = event.clientX
-      } else if (!this._pointerEvent) {
-        this.touchStartX = event.touches[0].clientX
-      }
-    }
-
-    const move = event => {
-      // ensure swiping with one touch and not pinching
-      this.touchDeltaX = event.touches && event.touches.length > 1 ?
-        0 :
-        event.touches[0].clientX - this.touchStartX
+    for (const itemImg of SelectorEngine.find(SELECTOR_ITEM_IMG, this._element)) {
+      EventHandler.on(itemImg, EVENT_DRAG_START, event => event.preventDefault())
     }
 
-    const end = event => {
-      if (hasPointerPenTouch(event)) {
-        this.touchDeltaX = event.clientX - this.touchStartX
-      }
-
-      this._handleSwipe()
+    const endCallBack = () => {
       if (this._config.pause === 'hover') {
         // If it's a touch-enabled device, mouseenter/leave are fired as
         // part of the mouse compatibility events on first tap - the carousel
@@ -304,20 +260,13 @@ class Carousel extends BaseComponent {
       }
     }
 
-    for (const itemImg of SelectorEngine.find(SELECTOR_ITEM_IMG, this._element)) {
-      EventHandler.on(itemImg, EVENT_DRAG_START, event => event.preventDefault())
+    const swipeConfig = {
+      leftCallback: () => this._slide(DIRECTION_LEFT),
+      rightCallback: () => this._slide(DIRECTION_RIGHT),
+      endCallback: endCallBack
     }
 
-    if (this._pointerEvent) {
-      EventHandler.on(this._element, EVENT_POINTERDOWN, event => start(event))
-      EventHandler.on(this._element, EVENT_POINTERUP, event => end(event))
-
-      this._element.classList.add(CLASS_NAME_POINTER_EVENT)
-    } else {
-      EventHandler.on(this._element, EVENT_TOUCHSTART, event => start(event))
-      EventHandler.on(this._element, EVENT_TOUCHMOVE, event => move(event))
-      EventHandler.on(this._element, EVENT_TOUCHEND, event => end(event))
-    }
+    this._swipeHelper = new Swipe(this._element, swipeConfig)
   }
 
   _keydown(event) {
diff --git a/js/src/util/swipe.js b/js/src/util/swipe.js
new file mode 100644
index 0000000000..321572eb8b
--- /dev/null
+++ b/js/src/util/swipe.js
@@ -0,0 +1,122 @@
+import EventHandler from '../dom/event-handler'
+import { execute, typeCheckConfig } from './index'
+
+const EVENT_KEY = '.bs.swipe'
+const EVENT_TOUCHSTART = `touchstart${EVENT_KEY}`
+const EVENT_TOUCHMOVE = `touchmove${EVENT_KEY}`
+const EVENT_TOUCHEND = `touchend${EVENT_KEY}`
+const EVENT_POINTERDOWN = `pointerdown${EVENT_KEY}`
+const EVENT_POINTERUP = `pointerup${EVENT_KEY}`
+const POINTER_TYPE_TOUCH = 'touch'
+const POINTER_TYPE_PEN = 'pen'
+const CLASS_NAME_POINTER_EVENT = 'pointer-event'
+const SWIPE_THRESHOLD = 40
+const NAME = 'swipe'
+
+const Default = {
+  leftCallback: null,
+  rightCallback: null,
+  endCallback: null
+}
+
+const DefaultType = {
+  leftCallback: '(function|null)',
+  rightCallback: '(function|null)',
+  endCallback: '(function|null)'
+}
+
+class Swipe {
+  constructor(element, config) {
+    this._element = element
+
+    if (!element || !Swipe.isSupported()) {
+      return
+    }
+
+    this._config = this._getConfig(config)
+    this._deltaX = 0
+    this._supportPointerEvents = Boolean(window.PointerEvent)
+    this._initEvents()
+  }
+
+  dispose() {
+    EventHandler.off(this._element, EVENT_KEY)
+  }
+
+  _start(event) {
+    if (!this._supportPointerEvents) {
+      this._deltaX = event.touches[0].clientX
+
+      return
+    }
+
+    if (this._eventIsPointerPenTouch(event)) {
+      this._deltaX = event.clientX
+    }
+  }
+
+  _end(event) {
+    if (this._eventIsPointerPenTouch(event)) {
+      this._deltaX = event.clientX - this._deltaX
+    }
+
+    this._handleSwipe()
+    execute(this._config.endCallback)
+  }
+
+  _move(event) {
+    this._deltaX = event.touches && event.touches.length > 1 ?
+      0 :
+      event.touches[0].clientX - this._deltaX
+  }
+
+  _handleSwipe() {
+    const absDeltaX = Math.abs(this._deltaX)
+
+    if (absDeltaX <= SWIPE_THRESHOLD) {
+      return
+    }
+
+    const direction = absDeltaX / this._deltaX
+
+    this._deltaX = 0
+
+    if (!direction) {
+      return
+    }
+
+    execute(direction > 0 ? this._config.rightCallback : this._config.leftCallback)
+  }
+
+  _initEvents() {
+    if (this._supportPointerEvents) {
+      EventHandler.on(this._element, EVENT_POINTERDOWN, event => this._start(event))
+      EventHandler.on(this._element, EVENT_POINTERUP, event => this._end(event))
+
+      this._element.classList.add(CLASS_NAME_POINTER_EVENT)
+    } else {
+      EventHandler.on(this._element, EVENT_TOUCHSTART, event => this._start(event))
+      EventHandler.on(this._element, EVENT_TOUCHMOVE, event => this._move(event))
+      EventHandler.on(this._element, EVENT_TOUCHEND, event => this._end(event))
+    }
+  }
+
+  _getConfig(config) {
+    config = {
+      ...Default,
+      ...(typeof config === 'object' ? config : {})
+    }
+    typeCheckConfig(NAME, config, DefaultType)
+    return config
+  }
+
+  _eventIsPointerPenTouch(event) {
+    return this._supportPointerEvents && (event.pointerType === POINTER_TYPE_PEN || event.pointerType === POINTER_TYPE_TOUCH)
+  }
+
+  static isSupported() {
+    return 'ontouchstart' in document.documentElement || navigator.maxTouchPoints > 0
+  }
+}
+
+export default Swipe