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

1 files changed, 122 insertions, 0 deletions

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