1 files changed, 135 insertions, 2 deletions
diff --git a/src/services/gesture_service/gesture_service.js b/src/services/gesture_service/gesture_service.js
index 88a328f3..265a7f25 100644
--- a/src/services/gesture_service/gesture_service.js
+++ b/src/services/gesture_service/gesture_service.js
@@ -4,9 +4,15 @@ const DIRECTION_RIGHT = [1, 0]
 const DIRECTION_UP = [0, -1]
 const DIRECTION_DOWN = [0, 1]
 
+const BUTTON_LEFT = 0
+
 const deltaCoord = (oldCoord, newCoord) => [newCoord[0] - oldCoord[0], newCoord[1] - oldCoord[1]]
 
-const touchEventCoord = e => ([e.touches[0].screenX, e.touches[0].screenY])
+const touchCoord = touch => [touch.screenX, touch.screenY]
+
+const touchEventCoord = e => touchCoord(e.touches[0])
+
+const pointerEventCoord = e => [e.clientX, e.clientY]
 
 const vectorLength = v => Math.sqrt(v[0] * v[0] + v[1] * v[1])
 
@@ -61,6 +67,132 @@ const updateSwipe = (event, gesture) => {
   gesture._swiping = false
 }
 
+class SwipeAndClickGesture {
+  // swipePreviewCallback(offsets: Array[Number])
+  //   offsets: the offset vector which the underlying component should move, from the starting position
+  // swipeEndCallback(sign: 0|-1|1)
+  //   sign: if the swipe does not meet the threshold, 0
+  //         if the swipe meets the threshold in the positive direction, 1
+  //         if the swipe meets the threshold in the negative direction, -1
+  constructor ({
+    direction,
+    // swipeStartCallback
+    swipePreviewCallback,
+    swipeEndCallback,
+    swipeCancelCallback,
+    swipelessClickCallback,
+    threshold = 30,
+    perpendicularTolerance = 1.0,
+    disableClickThreshold = 1
+  }) {
+    const nop = () => {}
+    this.direction = direction
+    this.swipePreviewCallback = swipePreviewCallback || nop
+    this.swipeEndCallback = swipeEndCallback || nop
+    this.swipeCancelCallback = swipeCancelCallback || nop
+    this.swipelessClickCallback = swipelessClickCallback || nop
+    this.threshold = typeof threshold === 'function' ? threshold : () => threshold
+    this.disableClickThreshold = typeof disableClickThreshold === 'function' ? disableClickThreshold : () => disableClickThreshold
+    this.perpendicularTolerance = perpendicularTolerance
+    this._reset()
+  }
+
+  _reset () {
+    this._startPos = [0, 0]
+    this._pointerId = -1
+    this._swiping = false
+    this._swiped = false
+    this._preventNextClick = false
+  }
+
+  start (event) {
+    // Only handle left click
+    if (event.button !== BUTTON_LEFT) {
+      return
+    }
+
+    this._startPos = pointerEventCoord(event)
+    this._pointerId = event.pointerId
+    this._swiping = true
+    this._swiped = false
+  }
+
+  move (event) {
+    if (this._swiping && this._pointerId === event.pointerId) {
+      this._swiped = true
+
+      const coord = pointerEventCoord(event)
+      const delta = deltaCoord(this._startPos, coord)
+
+      this.swipePreviewCallback(delta)
+    }
+  }
+
+  cancel (event) {
+    if (!this._swiping || this._pointerId !== event.pointerId) {
+      return
+    }
+
+    this.swipeCancelCallback()
+  }
+
+  end (event) {
+    if (!this._swiping) {
+      return
+    }
+
+    if (this._pointerId !== event.pointerId) {
+      return
+    }
+
+    this._swiping = false
+
+    // movement too small
+    const coord = pointerEventCoord(event)
+    const delta = deltaCoord(this._startPos, coord)
+
+    const sign = (() => {
+      if (vectorLength(delta) < this.threshold()) {
+        return 0
+      }
+      // movement is opposite from direction
+      const isPositive = dotProduct(delta, this.direction) > 0
+
+      // movement perpendicular to direction is too much
+      const towardsDir = project(delta, this.direction)
+      const perpendicularDir = perpendicular(this.direction)
+      const towardsPerpendicular = project(delta, perpendicularDir)
+      if (
+        vectorLength(towardsDir) * this.perpendicularTolerance <
+          vectorLength(towardsPerpendicular)
+      ) {
+        return 0
+      }
+
+      return isPositive ? 1 : -1
+    })()
+
+    if (this._swiped) {
+      this.swipeEndCallback(sign)
+    }
+    this._reset()
+    // Only a mouse will fire click event when
+    // the end point is far from the starting point
+    // so for other kinds of pointers do not check
+    // whether we have swiped
+    if (vectorLength(delta) >= this.disableClickThreshold() && event.pointerType === 'mouse') {
+      this._preventNextClick = true
+    }
+  }
+
+  click (event) {
+    if (!this._preventNextClick) {
+      this.swipelessClickCallback()
+    }
+    this._reset()
+  }
+}
+
 const GestureService = {
   DIRECTION_LEFT,
   DIRECTION_RIGHT,
@@ -68,7 +200,8 @@ const GestureService = {
   DIRECTION_DOWN,
   swipeGesture,
   beginSwipe,
-  updateSwipe
+  updateSwipe,
+  SwipeAndClickGesture
 }
 
 export default GestureService