feat: implement horizontal drag-to-scroll functionality in board views (#326)

apps/web/src/hooks/useDragToScroll.ts

@@ -0,0 +1,113 @@
+import { useEffect, useRef, useState } from "react";
+
+interface UseDragToScrollOptions {
+  /**
+   * Whether drag-to-scroll is enabled
+   */
+  enabled?: boolean;
+  /**
+   * The direction to scroll
+   */
+  direction?: "horizontal" | "vertical" | "both";
+}
+
+/**
+ * Hook to enable drag-to-scroll functionality on a scrollable element
+ * @param options Configuration options
+ * @returns Ref to attach to the scrollable element and mouse event handlers
+ */
+export function useDragToScroll({
+  enabled = true,
+  direction = "horizontal",
+}: UseDragToScrollOptions = {}) {
+  const scrollRef = useRef<HTMLDivElement>(null);
+  const [isDragging, setIsDragging] = useState(false);
+  const startPosRef = useRef({ x: 0, y: 0 });
+  const scrollStartRef = useRef({ x: 0, y: 0 });
+
+  useEffect(() => {
+    if (!enabled || !isDragging) return;
+
+    const handleMouseMove = (e: MouseEvent) => {
+      if (!scrollRef.current) return;
+
+      const deltaX = e.clientX - startPosRef.current.x;
+      const deltaY = e.clientY - startPosRef.current.y;
+
+      if (direction === "horizontal" || direction === "both") {
+        scrollRef.current.scrollLeft = scrollStartRef.current.x - deltaX;
+      }
+      if (direction === "vertical" || direction === "both") {
+        scrollRef.current.scrollTop = scrollStartRef.current.y - deltaY;
+      }
+    };
+
+    const handleMouseUp = () => {
+      setIsDragging(false);
+    };
+
+    document.addEventListener("mousemove", handleMouseMove);
+    document.addEventListener("mouseup", handleMouseUp);
+    document.body.style.cursor = "grabbing";
+    document.body.style.userSelect = "none";
+
+    return () => {
+      document.removeEventListener("mousemove", handleMouseMove);
+      document.removeEventListener("mouseup", handleMouseUp);
+      document.body.style.cursor = "";
+      document.body.style.userSelect = "";
+    };
+  }, [enabled, isDragging, direction]);
+
+  const handleMouseDown = (e: React.MouseEvent<HTMLDivElement>) => {
+    if (!scrollRef.current) return;
+
+    const target = e.target as HTMLElement;
+    const container = scrollRef.current;
+
+    // Check if the click is on an interactive or draggable element
+    // We need to be careful not to interfere with react-beautiful-dnd dragging
+    const isInteractiveElement =
+      target.closest("a") ||
+      target.closest("button") ||
+      target.closest("input") ||
+      target.closest("textarea") ||
+      target.closest("[role='button']") ||
+      target.closest("[draggable='true']") ||
+      target.closest(".react-beautiful-dnd-drag-handle") ||
+      target.closest("[data-rbd-drag-handle-draggable-id]") ||
+      target.closest("[data-rbd-draggable-id]");
+
+    // Don't start dragging if clicking on interactive elements
+    if (isInteractiveElement) return;
+
+    // Check if clicking directly on the container (background)
+    const isContainer = target === container;
+    
+    // Check if clicking on a spacer div (empty space between lists)
+    // Spacer divs are direct children with minimal/no content
+    const isDirectChild = container.contains(target) && target.parentElement === container;
+    const isSpacer = 
+      isDirectChild &&
+      target.textContent?.trim() === "" &&
+      target.children.length === 0 &&
+      !target.closest("[data-rbd-droppable-id]");
+
+    // Allow dragging if clicking on the container background or spacer elements
+    if (isContainer || isSpacer) {
+      e.preventDefault();
+      setIsDragging(true);
+      startPosRef.current = { x: e.clientX, y: e.clientY };
+      scrollStartRef.current = {
+        x: container.scrollLeft,
+        y: container.scrollTop,
+      };
+    }
+  };
+
+  return {
+    ref: scrollRef,
+    onMouseDown: handleMouseDown,
+    isDragging,
+  };
+}

apps/web/src/views/board/index.tsx

@@ -25,6 +25,7 @@ import PatternedBackground from "~/components/PatternedBackground";
 import { StrictModeDroppable as Droppable } from "~/components/StrictModeDroppable";
 import { Tooltip } from "~/components/Tooltip";
 import { EditYouTubeModal } from "~/components/YouTubeEmbed/EditYouTubeModal";
+import { useDragToScroll } from "~/hooks/useDragToScroll";
 import { useKeyboardShortcut } from "~/providers/keyboard-shortcuts";
 import { useModal } from "~/providers/modal";
 import { usePopup } from "~/providers/popup";
@@ -56,6 +57,11 @@ export default function BoardPage({ isTemplate }: { isTemplate?: boolean }) {
   const [selectedPublicListId, setSelectedPublicListId] =
     useState<PublicListId>("");
   const [isInitialLoading, setIsInitialLoading] = useState(true);
+  
+  const { ref: scrollRef, onMouseDown } = useDragToScroll({
+    enabled: true,
+    direction: "horizontal",
+  });
 
   const { tooltipContent: createListShortcutTooltipContent } =
     useKeyboardShortcut({
@@ -479,7 +485,11 @@ export default function BoardPage({ isTemplate }: { isTemplate?: boolean }) {
           </div>
         </div>
 
-        <div className="scrollbar-w-none scrollbar-track-rounded-[4px] scrollbar-thumb-rounded-[4px] scrollbar-h-[8px] z-0 flex-1 overflow-y-hidden overflow-x-scroll overscroll-contain scrollbar scrollbar-track-light-200 scrollbar-thumb-light-400 dark:scrollbar-track-dark-100 dark:scrollbar-thumb-dark-300">
+        <div
+          ref={scrollRef}
+          onMouseDown={onMouseDown}
+          className={`scrollbar-w-none scrollbar-track-rounded-[4px] scrollbar-thumb-rounded-[4px] scrollbar-h-[8px] z-0 flex-1 overflow-y-hidden overflow-x-scroll overscroll-contain scrollbar scrollbar-track-light-200 scrollbar-thumb-light-400 dark:scrollbar-track-dark-100 dark:scrollbar-thumb-dark-300`}
+        >
           {isLoading ? (
             <div className="ml-[2rem] flex">
               <div className="0 mr-5 h-[500px] w-[18rem] animate-pulse rounded-md bg-light-200 dark:bg-dark-100" />

apps/web/src/views/public/board/index.tsx

@@ -12,6 +12,7 @@ import { PageHead } from "~/components/PageHead";
 import PatternedBackground from "~/components/PatternedBackground";
 import Popup from "~/components/Popup";
 import ThemeToggle from "~/components/ThemeToggle";
+import { useDragToScroll } from "~/hooks/useDragToScroll";
 import { useModal } from "~/providers/modal";
 import { usePopup } from "~/providers/popup";
 import { api } from "~/utils/api";
@@ -29,6 +30,11 @@ export default function PublicBoardView() {
   const { showPopup } = usePopup();
   const [isRouteLoaded, setIsRouteLoaded] = useState(false);
   const { openModal } = useModal();
+  
+  const { ref: scrollRef, onMouseDown } = useDragToScroll({
+    enabled: true,
+    direction: "horizontal",
+  });
 
   const boardSlug = Array.isArray(router.query.boardSlug)
     ? router.query.boardSlug[0]
@@ -151,7 +157,11 @@ export default function PublicBoardView() {
             )}
           </div>
 
-          <div className="scrollbar-w-none scrollbar-track-rounded-[4px] scrollbar-thumb-rounded-[4px] scrollbar-h-[8px] relative h-full flex-1 overflow-y-hidden overflow-x-scroll overscroll-contain scrollbar scrollbar-track-light-200 scrollbar-thumb-light-400 dark:scrollbar-track-dark-100 dark:scrollbar-thumb-dark-300">
+          <div
+            ref={scrollRef}
+            onMouseDown={onMouseDown}
+            className="scrollbar-w-none scrollbar-track-rounded-[4px] scrollbar-thumb-rounded-[4px] scrollbar-h-[8px] relative h-full flex-1 overflow-y-hidden overflow-x-scroll overscroll-contain scrollbar scrollbar-track-light-200 scrollbar-thumb-light-400 dark:scrollbar-track-dark-100 dark:scrollbar-thumb-dark-300"
+          >
             {isLoading || !router.isReady ? (
               <div className="ml-[2rem] flex">
                 <div className="0 mr-5 h-[500px] w-[18rem] animate-pulse rounded-md bg-light-200 dark:bg-dark-100" />