feat(component): Adds SmartScrollbar to ui-next - OHIF-2558

platform/ui-next/jest.config.js

@@ -0,0 +1,10 @@
+const base = require('../../jest.config.base.js');
+const pkg = require('./package');
+
+module.exports = {
+  ...base,
+  displayName: pkg.name,
+
+  // Override the base setting that transforms node_modules.
+  transformIgnorePatterns: ['/node_modules/'],
+};

platform/ui-next/package.json

@@ -17,6 +17,8 @@
     "start": "yarn run build --watch",
     "dev": "cross-env NODE_ENV=development webpack serve --config .webpack/webpack.playground.js",
     "test": "echo \"Error: no test specified\" && exit 1",
+    "test:unit": "jest --watchAll",
+    "test:unit:ci": "jest --ci --runInBand --collectCoverage",
     "build": "cross-env NODE_ENV=production webpack --config .webpack/webpack.prod.js",
     "build:package": "yarn run build"
   },

platform/ui-next/src/components/SmartScrollbar/SmartScrollbar.tsx

@@ -0,0 +1,292 @@
+import React, {
+  createContext,
+  useContext,
+  useState,
+  useEffect,
+  useRef,
+  useCallback,
+  useMemo,
+  Children,
+  isValidElement,
+} from 'react';
+import { getIndicatorLayout } from './utils';
+import { SmartScrollbarIndicator } from './SmartScrollbarIndicator';
+
+// ── Child validation ────────────────────────────────────────────
+function validateChildren(children: React.ReactNode): void {
+  let hasIndicator = false;
+
+  Children.forEach(children, child => {
+    if (!isValidElement(child)) return;
+    if (child.type === SmartScrollbarIndicator) hasIndicator = true;
+  });
+
+  if (!hasIndicator) {
+    throw new Error(
+      'SmartScrollbar: <SmartScrollbarIndicator> is a required child. ' +
+        'Users will not see their current scroll position without it.'
+    );
+  }
+}
+
+// ── Layout and timing constants ─────────────────────────────────
+const TRACK_WIDTH = 8;
+const RESTING_WIDTH = 4;
+const FILL_PADDING = 3;
+const INDICATOR_SIZE = 8;
+const INDICATOR_BORDER_WIDTH = 1;
+const SETTLE_DELAY = 600;
+
+// ── Contexts ───────────────────────────────────────────────────
+export interface SmartScrollbarLayoutContextValue {
+  total: number;
+  trackHeight: number;
+  isLoading: boolean;
+  effectiveWidth: number;
+  trackWidth: number;
+  fillPadding: number;
+  stableLayerEl: HTMLDivElement | null;
+}
+
+const SmartScrollbarLayoutContext = createContext<SmartScrollbarLayoutContextValue | null>(null);
+const SmartScrollbarScrollContext = createContext<number | null>(null);
+
+export function useSmartScrollbarLayoutContext(): SmartScrollbarLayoutContextValue {
+  const ctx = useContext(SmartScrollbarLayoutContext);
+  if (!ctx)
+    throw new Error('SmartScrollbar compound components must be used inside <SmartScrollbar>');
+  return ctx;
+}
+
+export function useSmartScrollbarScrollContext(): number {
+  const value = useContext(SmartScrollbarScrollContext);
+  if (value === null)
+    throw new Error('SmartScrollbar compound components must be used inside <SmartScrollbar>');
+  return value;
+}
+
+// ── Props ──────────────────────────────────────────────────────
+interface SmartScrollbarProps {
+  value: number;
+  total: number;
+  onValueChange: (index: number) => void;
+  isLoading?: boolean;
+  enableKeyboardNavigation?: boolean;
+  'aria-label'?: string;
+  className?: string;
+  children: React.ReactNode;
+}
+
+// ── Component ──────────────────────────────────────────────────
+export function SmartScrollbar({
+  value,
+  total,
+  onValueChange,
+  isLoading = false,
+  enableKeyboardNavigation = false,
+  'aria-label': ariaLabel = 'Scroll position',
+  className,
+  children,
+}: SmartScrollbarProps) {
+  validateChildren(children);
+
+  // ── ResizeObserver for trackHeight ───────────────────────────
+  const containerRef = useRef<HTMLDivElement>(null);
+  const [trackHeight, setTrackHeight] = useState(0);
+
+  useEffect(() => {
+    const el = containerRef.current;
+    if (!el) return;
+    const ro = new ResizeObserver(([entry]) => {
+      setTrackHeight(entry.contentRect.height);
+    });
+    ro.observe(el);
+    return () => ro.disconnect();
+  }, []);
+
+  // ── Contraction state ────────────────────────────────────────
+  const [isHovered, setIsHovered] = useState(false);
+  const [isDragging, setIsDragging] = useState(false);
+  const isDraggingRef = useRef(false);
+  const trackTopRef = useRef(0);
+
+  // Settle delay — only contract after a real loading→done transition
+  const [hasSettled, setHasSettled] = useState(false);
+  const wasEverLoading = useRef(false);
+
+  useEffect(() => {
+    if (isLoading) {
+      wasEverLoading.current = true;
+      setHasSettled(false);
+    } else if (wasEverLoading.current) {
+      const timer = setTimeout(() => setHasSettled(true), SETTLE_DELAY);
+      return () => clearTimeout(timer);
+    }
+  }, [isLoading]);
+
+  const isExpanded = !hasSettled || isHovered || isDragging;
+  const effectiveWidth = isExpanded ? TRACK_WIDTH : RESTING_WIDTH;
+
+  // ── Hit zone extension ───────────────────────────────────────
+  const { leftPos } = getIndicatorLayout(TRACK_WIDTH, INDICATOR_SIZE, INDICATOR_BORDER_WIDTH);
+  const hitZoneLeftExtension = Math.max(0, -leftPos);
+
+  // ── Stable layer (for elements that shouldn't move during contraction) ──
+  // Uses useState + callback ref so React triggers a re-render when the
+  // DOM node mounts — ensuring endpoints render on the first valid pass.
+  const [stableLayerEl, setStableLayerEl] = useState<HTMLDivElement | null>(null);
+
+  // ── Pointer helpers ──────────────────────────────────────────
+  const clamp = useCallback(
+    (val: number) => Math.max(0, Math.min(total - 1, val)),
+    [total]
+  );
+
+  const indexFromPointerY = useCallback(
+    (clientY: number) => {
+      const ratio = Math.max(0, Math.min(1, (clientY - trackTopRef.current) / trackHeight));
+      return Math.round(ratio * (total - 1));
+    },
+    [trackHeight, total]
+  );
+
+  const handlePointerDown = useCallback(
+    (e: React.PointerEvent) => {
+      trackTopRef.current = e.currentTarget.getBoundingClientRect().top;
+
+      isDraggingRef.current = true;
+      setIsDragging(true);
+      e.currentTarget.setPointerCapture(e.pointerId);
+
+      onValueChange(clamp(indexFromPointerY(e.clientY)));
+    },
+    [clamp, indexFromPointerY, onValueChange]
+  );
+
+  const handlePointerMove = useCallback(
+    (e: React.PointerEvent) => {
+      if (!isDraggingRef.current) return;
+      onValueChange(clamp(indexFromPointerY(e.clientY)));
+    },
+    [clamp, indexFromPointerY, onValueChange]
+  );
+
+  const handlePointerUp = useCallback((e: React.PointerEvent) => {
+    isDraggingRef.current = false;
+    setIsDragging(false);
+    e.currentTarget.releasePointerCapture(e.pointerId);
+  }, []);
+
+  // ── Keyboard interaction (WAI-ARIA slider spec) ────────────
+  const PAGE_STEP = 10;
+
+  const handleKeyDown = useCallback(
+    (e: React.KeyboardEvent) => {
+      let next: number | null = null;
+
+      switch (e.key) {
+        case 'ArrowUp':
+        case 'ArrowLeft':
+          next = value - 1;
+          break;
+        case 'ArrowDown':
+        case 'ArrowRight':
+          next = value + 1;
+          break;
+        case 'PageUp':
+          next = value - PAGE_STEP;
+          break;
+        case 'PageDown':
+          next = value + PAGE_STEP;
+          break;
+        case 'Home':
+          next = 0;
+          break;
+        case 'End':
+          next = total - 1;
+          break;
+        default:
+          return;
+      }
+
+      e.preventDefault();
+      onValueChange(clamp(next));
+    },
+    [value, total, clamp, onValueChange]
+  );
+
+  // ── Context values ───────────────────────────────────────────
+  const layoutCtx = useMemo<SmartScrollbarLayoutContextValue>(() => ({
+    total,
+    trackHeight,
+    isLoading,
+    effectiveWidth,
+    trackWidth: TRACK_WIDTH,
+    fillPadding: FILL_PADDING,
+    stableLayerEl,
+  }), [total, trackHeight, isLoading, effectiveWidth, stableLayerEl]);
+  return (
+    <SmartScrollbarLayoutContext.Provider value={layoutCtx}>
+      <SmartScrollbarScrollContext.Provider value={value}>
+        <div
+          ref={containerRef}
+          role="slider"
+          aria-valuenow={value}
+          aria-valuemin={0}
+          aria-valuemax={total - 1}
+          aria-orientation="vertical"
+          aria-label={ariaLabel}
+          tabIndex={0}
+          className={className}
+          style={{
+            width: TRACK_WIDTH + hitZoneLeftExtension,
+            height: '100%',
+            position: 'relative',
+            marginLeft: -hitZoneLeftExtension,
+            cursor: isDragging ? 'grabbing' : 'grab',
+            touchAction: 'none',
+          }}
+          onPointerEnter={() => setIsHovered(true)}
+          onPointerLeave={() => setIsHovered(false)}
+          onPointerDown={handlePointerDown}
+          onPointerMove={handlePointerMove}
+          onPointerUp={handlePointerUp}
+          onPointerCancel={handlePointerUp}
+          onKeyDown={enableKeyboardNavigation ? handleKeyDown : undefined}
+        >
+          {trackHeight > 0 && (
+            <div
+              style={{
+                position: 'absolute',
+                right: 0,
+                top: 0,
+                width: TRACK_WIDTH,
+                height: trackHeight,
+                display: 'flex',
+                justifyContent: 'center',
+              }}
+            >
+              <div
+                className="relative"
+                style={{
+                  width: effectiveWidth,
+                  height: trackHeight,
+                  transition: 'width 300ms ease',
+                }}
+              >
+                {children}
+              </div>
+              {/* Stable layer — always TRACK_WIDTH, never contracts. For elements like
+                endpoints that must not jitter during width transitions. Children
+                render here via createPortal using stableLayerRef from context. */}
+              <div
+                ref={setStableLayerEl}
+                style={{ position: 'absolute', inset: 0, pointerEvents: 'none' }}
+              />
+            </div>
+          )}
+        </div>
+      </SmartScrollbarScrollContext.Provider>
+    </SmartScrollbarLayoutContext.Provider>
+  );
+}