From 740160c39103019cc41677ea98541c8dd74ee3a1 Mon Sep 17 00:00:00 2001
From: Emil Kowalski <36730035+emilkowalski@users.noreply.github.com>
Date: Fri, 10 Nov 2023 01:50:52 +0100
Subject: [PATCH] Fix drag issue when element is scrollable (#167)

* Fix scrolling issue

* Refactor so that scroll is only disabled on scrollable elements

* Fix scorlling down

* Polish
---
 src/index.tsx                                | 44 +++++++++++++-------
 src/style.css                                |  4 ++
 test/src/app/scrollable-with-inputs/page.tsx |  2 +-
 3 files changed, 34 insertions(+), 16 deletions(-)

diff --git a/src/index.tsx b/src/index.tsx
index e043d470..d30f76cf 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -13,7 +13,7 @@ import { TRANSITIONS, VELOCITY_THRESHOLD } from './constants';
 
 const CLOSE_THRESHOLD = 0.25;
 
-const SCROLL_LOCK_TIMEOUT = 500;
+const SCROLL_LOCK_TIMEOUT = 100;
 
 const BORDER_RADIUS = 8;
 
@@ -21,6 +21,8 @@ const NESTED_DISPLACEMENT = 16;
 
 const WINDOW_TOP_OFFSET = 26;
 
+const DRAG_CLASS = 'vaul-dragging';
+
 interface WithFadeFromProps {
   snapPoints: (number | string)[];
   fadeFromIndex: number;
@@ -139,7 +141,6 @@ function Root({
     if (isIOS()) {
       window.addEventListener('touchend', () => (isAllowedToDrag.current = false), { once: true });
     }
-
     // Ensure we maintain correct pointer capture even when going outside of the drawer
     (event.target as HTMLElement).setPointerCapture(event.pointerId);
 
@@ -176,27 +177,27 @@ function Root({
       return false;
     }
 
+    if (isDraggingDown) {
+      lastTimeDragPrevented.current = new Date();
+
+      // We are dragging down so we should allow scrolling
+      return false;
+    }
+
     // Keep climbing up the DOM tree as long as there's a parent
     while (element) {
       // Check if the element is scrollable
       if (element.scrollHeight > element.clientHeight) {
-        if (element.getAttribute('role') === 'dialog') {
-          return true;
-        }
-
-        if (isDraggingDown && element !== document.body && !swipeAmount && swipeAmount >= 0) {
-          lastTimeDragPrevented.current = new Date();
-
-          // Element is scrolled to the top, but we are dragging down so we should allow scrolling
-          return false;
-        }
-
         if (element.scrollTop !== 0) {
           lastTimeDragPrevented.current = new Date();
 
           // The element is scrollable and not scrolled to the top, so don't drag
           return false;
         }
+
+        if (element.getAttribute('role') === 'dialog') {
+          return true;
+        }
       }
 
       // Move up to the parent element
@@ -217,7 +218,7 @@ function Root({
       if (snapPoints && activeSnapPointIndex === 0 && !dismissible) return;
 
       if (!isAllowedToDrag.current && !shouldDrag(event.target, isDraggingDown)) return;
-
+      drawerRef.current.classList.add(DRAG_CLASS);
       // If shouldDrag gave true once after pressing down on the drawer, we set isAllowedToDrag to true and it will remain true until we let go, there's no reason to disable dragging mid way, ever, and that's the solution to it
       isAllowedToDrag.current = true;
       set(drawerRef.current, {
@@ -459,7 +460,7 @@ function Root({
       // If we were just dragging, prevent focusing on inputs etc. on release
       (event.target as HTMLInputElement).blur();
     }
-
+    drawerRef.current.classList.remove(DRAG_CLASS);
     isAllowedToDrag.current = false;
     setIsDragging(false);
     dragEndTime.current = new Date();
@@ -526,6 +527,19 @@ function Root({
     }
   }, [isOpen]);
 
+  React.useEffect(() => {
+    if (visible && visible) {
+      // Find all scrollable elements inside our drawer and assign a class to it so that we can disable overflow when dragging to prevent pointermove not being captured
+      const children = drawerRef.current.querySelectorAll('*');
+      children.forEach((child: Element) => {
+        const htmlChild = child as HTMLElement;
+        if (htmlChild.scrollHeight > htmlChild.clientHeight || htmlChild.scrollWidth > htmlChild.clientWidth) {
+          htmlChild.classList.add('vaul-scrollable');
+        }
+      });
+    }
+  }, [visible]);
+
   function scaleBackground(open: boolean) {
     const wrapper = document.querySelector('[vaul-drawer-wrapper]');
 
diff --git a/src/style.css b/src/style.css
index 1adee655..336ed701 100644
--- a/src/style.css
+++ b/src/style.css
@@ -4,6 +4,10 @@
   transition: transform 0.5s cubic-bezier(0.32, 0.72, 0, 1);
 }
 
+.vaul-dragging .vaul-scrollable {
+  overflow-y: hidden !important;
+}
+
 [vaul-drawer][vaul-drawer-visible='true'] {
   transform: translate3d(0, var(--snap-point-height, 0), 0);
 }
diff --git a/test/src/app/scrollable-with-inputs/page.tsx b/test/src/app/scrollable-with-inputs/page.tsx
index a3704b93..a56faab4 100644
--- a/test/src/app/scrollable-with-inputs/page.tsx
+++ b/test/src/app/scrollable-with-inputs/page.tsx
@@ -12,7 +12,7 @@ export default function Page() {
         <Drawer.Portal>
           <Drawer.Overlay className="fixed inset-0 bg-black/40" />
           <Drawer.Content className="bg-white flex flex-col fixed bottom-0 left-0 right-0 max-h-[82vh] rounded-t-[10px]">
-            <div className="max-w-md w-full mx-auto flex flex-col overflow-auto p-4 rounded-t-[10px]">
+            <div className="max-w-md w-full mx-auto overflow-auto p-4 rounded-t-[10px]">
               <input className="border border-gray-400 my-8" placeholder="Input" />
               <p>
                 But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born