changing webkit hack

src/view/use-drag-handle/sensor/use-touch-sensor.js

@@ -15,6 +15,7 @@ import supportedPageVisibilityEventName from '../util/supported-page-visibility-
 import createPostDragEventPreventer, {
   type EventPreventer,
 } from '../util/create-post-drag-event-preventer';
+import useLayoutEffect from '../../use-isomorphic-layout-effect';
 
 export type Args = {|
   callbacks: Callbacks,
@@ -36,75 +37,13 @@ type TouchWithForce = Touch & {
   force: number,
 };
 
-type WebkitHack = {|
-  preventTouchMove: () => void,
-  releaseTouchMove: () => void,
-|};
-
-export const timeForLongPress: number = 150;
+// Decreased from 150 as a work around for an issue for forcepress on iOS
+// https://github.com/atlassian/react-beautiful-dnd/issues/1401
+export const timeForLongPress: number = 120;
 export const forcePressThreshold: number = 0.15;
 const touchStartMarshal: EventMarshal = createEventMarshal();
 const noop = (): void => {};
 
-// Webkit does not allow event.preventDefault() in dynamically added handlers
-// So we add an always listening event handler to get around this :(
-// webkit bug: https://bugs.webkit.org/show_bug.cgi?id=184250
-const webkitHack: WebkitHack = (() => {
-  const stub: WebkitHack = {
-    preventTouchMove: noop,
-    releaseTouchMove: noop,
-  };
-
-  // Do nothing when server side rendering
-  if (typeof window === 'undefined') {
-    return stub;
-  }
-
-  // Device has no touch support - no point adding the touch listener
-  if (!('ontouchstart' in window)) {
-    return stub;
-  }
-
-  // Not adding any user agent testing as everything pretends to be webkit
-
-  let isBlocking: boolean = false;
-
-  // Adding a persistent event handler
-  window.addEventListener(
-    'touchmove',
-    (event: TouchEvent) => {
-      // We let the event go through as normal as nothing
-      // is blocking the touchmove
-      if (!isBlocking) {
-        return;
-      }
-
-      // Our event handler would have worked correctly if the browser
-      // was not webkit based, or an older version of webkit.
-      if (event.defaultPrevented) {
-        return;
-      }
-
-      // Okay, now we need to step in and fix things
-      event.preventDefault();
-
-      // Forcing this to be non-passive so we can get every touchmove
-      // Not activating in the capture phase like the dynamic touchmove we add.
-      // Technically it would not matter if we did this in the capture phase
-    },
-    { passive: false, capture: false },
-  );
-
-  const preventTouchMove = () => {
-    isBlocking = true;
-  };
-  const releaseTouchMove = () => {
-    isBlocking = false;
-  };
-
-  return { preventTouchMove, releaseTouchMove };
-})();
-
 export default function useTouchSensor(args: Args): OnTouchStart {
   const {
     callbacks,
@@ -143,7 +82,6 @@ export default function useTouchSensor(args: Args): OnTouchStart {
     schedule.cancel();
     unbindWindowEventsRef.current();
     touchStartMarshal.reset();
-    webkitHack.releaseTouchMove();
     hasMovedRef.current = false;
     onCaptureEnd();
 
@@ -196,11 +134,15 @@ export default function useTouchSensor(args: Args): OnTouchStart {
             hasMovedRef.current = true;
           }
 
-          const { clientX, clientY } = event.touches[0];
+          const touch: ?Touch = event.touches[0];
+
+          if (!touch) {
+            return;
+          }
 
           const point: Position = {
-            x: clientX,
-            y: clientY,
+            x: touch.clientX,
+            y: touch.clientY,
           };
 
           // We need to prevent the default event in order to block native scrolling
@@ -437,11 +379,25 @@ export default function useTouchSensor(args: Args): OnTouchStart {
     // browser interactions as possible.
     // This includes navigation on anchors which we want to preserve
     touchStartMarshal.handle();
-
-    // A webkit only hack to prevent touch move events
-    webkitHack.preventTouchMove();
     startPendingDrag(event);
   };
 
+  // This is needed for safari
+  // Simply adding a non capture, non passive 'touchmove' listener.
+  // This forces event.preventDefault() in dynamically added
+  // touchmove event handlers to actually work
+  // https://github.com/atlassian/react-beautiful-dnd/issues/1374
+  useLayoutEffect(function webkitHack() {
+    const unbind = bindEvents(window, [
+      {
+        eventName: 'touchmove',
+        fn: noop,
+        options: { capture: false, passive: false },
+      },
+    ]);
+
+    return unbind;
+  }, []);
+
   return onTouchStart;
 }