u

src/FillSpace.jsx

@@ -1,72 +1,110 @@
 import { Component } from 'react';
 import Box from '@mui/material/Box';
+import List from '@mui/material/List';
+import Pagination from '@mui/material/Pagination';
+import Typography from '@mui/material/Typography';
 import { alpha } from '@mui/material/styles';
 
 /**
- * Vertical spacer that fills the remaining viewport height between the content
- * above it and (optionally) a footer below it — useful for creating scrollable
- * middle sections in apps with fixed headers/footers.
+ * FillSpace — paginates `items`.
  *
  * @component FillSpace
  * @import dashgui/FillSpace
  * @defaultExport
  *
- * @prop {React.Ref} [aboveRef] - Ref to the element immediately above the spacer. It is observed (not strictly required) so the spacer re-measures when that element's height changes.
- * @prop {React.Ref} [belowRef] - Ref to the footer element below. Its height (plus top margin) is reserved so the footer stays visible without page scrolling.
- * @prop {ReactNode} [measureElement] - When given, this element is used as the measurement unit of the spacer: its height is read from a hidden copy and it is repeated top-to-bottom to fill only the leftover space below `children` (like a repeating ruler/row pattern). When omitted, only `children` are rendered.
- * @prop {number} [measureGap=0] - Vertical gap (px) between repeated `measureElement` units.
- * @prop {(count: number) => void} [onMeasurement] - Called whenever the number of `measureElement` units that would fit in the whole spacer height changes, as if there were no `children` (i.e. the total row count the space could hold). Fires once after mount with the initial count.
- * @prop {number} [minHeight=0] - Minimum spacer height in px.
- * @prop {number} [maxHeight] - Optional maximum spacer height in px.
- * @prop {boolean} [debug=false] - When true, draws a dashed outline around the spacer and a translucent overlay over the whole viewport so the measured bounds are visible.
- * @prop {ReactNode} [children] - Real content rendered at the top of the spacer. The repeated `measureElement` units (if any) fill the remaining space below it.
- * @prop {object} [sx] - Extra styles merged into the Box.
- *
- * @behaviour Fills to the bottom of the initial viewport: height = viewport height − spacer's distance from the document top − reserved below height.
- * @behaviour The distance-from-top is read from the spacer's own position (document-relative), so every element above (including their margins and the parent's padding) is accounted for, and scrolling the page does not change the computed height.
- * @behaviour When `measureElement` is set, `children` are rendered on top and the units fill only `height − contentHeight`, so no units are shown once the content already fills the space.
- * @behaviour `onMeasurement` fires with the count of units that would fit in the whole spacer height (as if `children` were absent) — not the number actually rendered below the content — whenever that count changes.
- * @behaviour Re-measures on window resize and whenever the observed refs or the content change size (ResizeObserver), throttled with requestAnimationFrame.
- * @behaviour `debug` draws a dashed primary outline around the spacer plus a translucent full-viewport overlay.
+ * @prop {Array} items - Wheel flips pages.
+ * @prop {React.ComponentType|Function} renderItem - Row renderer (component or callback).
+ * @prop {number} [minPageSize=10] - Rows per page.
+ * @prop {(page: number) => void} [onPageChange] - Called on page change.
+ * @prop {boolean} [debug=false] - Dashed outline for layout debugging.
+ * @prop {object} [sx] - Extra styles.
  */
+
+/** True for class components (e.g. `renderItem={ArtikelMarke}`). Rendered as element, not called. */
+function isRowComponent(renderItem) {
+  return (
+    typeof renderItem === 'function' &&
+    (renderItem.prototype?.isReactComponent || renderItem.isFillRowComponent === true)
+  );
+}
+
+/** Renders one row: component types become `<Row brand item index />`, callbacks are called. */
+function renderRowElement(renderItem, item, index) {
+  if (isRowComponent(renderItem)) {
+    const Row = renderItem;
+    return <Row brand={item} item={item} index={index} />;
+  }
+  return renderItem(item, index);
+}
+
+/**
+ * Data-free probe of the row height, rendered hidden. Class components
+ * (e.g. `renderItem={ArtikelMarke}`) tolerate empty props
+ * (`brand`/`item` undefined) and keep a fixed height (40px thumb /
+ * text field), so the probe measures the row without depending on the
+ * first data element. Plain callbacks are NOT probed — calling arbitrary
+ * user code with `undefined` could throw — they fall back to the first
+ * rendered data row.
+ */
+function renderProbeElement(renderItem) {
+  if (!isRowComponent(renderItem)) return null;
+  const Row = renderItem;
+  return <Row brand={undefined} item={undefined} index={0} disabled />;
+}
+
 class FillSpace extends Component {
   constructor(props) {
     super(props);
     this.state = {
-      height: 0,
       unitHeight: 0,
-      contentHeight: 0,
-      totalCount: 0,
-      fillCount: 0,
+      viewportHeight: null,
+      pageSize: Number(props.minPageSize) || 10,
+      currentPage: 1,
     };
-    this.lastTotalCount = null;
     this.ref = null;
-    this.contentRef = null;
-    this.unitRef = null;
+    this.probeRef = null;
+    this.wheelAcc = 0;
     this.observer = null;
     this.raf = null;
   }
 
   componentDidMount() {
-    requestAnimationFrame(() => {
-      this._measure();
-      this._observe();
-    });
+    this._probeMeasure();
+    this._viewportMeasure();
+    this._observe();
     window.addEventListener('resize', this._onViewportChange);
   }
 
   componentDidUpdate(prevProps) {
+    if (prevProps.renderItem !== this.props.renderItem) {
+      this._probeMeasure();
+    }
+    if (prevProps.minPageSize !== this.props.minPageSize) {
+      this.setState({ pageSize: Number(this.props.minPageSize) || 10 });
+    }
     if (
       prevProps.aboveRef !== this.props.aboveRef ||
       prevProps.belowRef !== this.props.belowRef ||
       prevProps.containerRef !== this.props.containerRef ||
-      prevProps.minHeight !== this.props.minHeight ||
-      prevProps.maxHeight !== this.props.maxHeight ||
-      prevProps.measureElement !== this.props.measureElement ||
-      prevProps.measureGap !== this.props.measureGap
+      prevProps.reserveBottom !== this.props.reserveBottom ||
+      prevProps.items !== this.props.items
     ) {
       this._observe();
-      this._measure();
+      this._viewportMeasure();
+    }
+    // Clamp current page when the item list shrinks (e.g. brand deleted).
+    if (
+      Array.isArray(this.props.items) &&
+      this.props.items !== prevProps.items
+    ) {
+      const pageCount = Math.max(
+        1,
+        Math.ceil(this.props.items.length / Math.max(1, this.state.pageSize)),
+      );
+      if (this.state.currentPage > pageCount) {
+        this.setState({ currentPage: pageCount });
+        this.props.onPageChange?.(pageCount);
+      }
     }
   }
 
@@ -86,7 +124,7 @@ class FillSpace extends Component {
     if (this.raf) return;
     this.raf = requestAnimationFrame(() => {
       this.raf = null;
-      this._measure();
+      this._viewportMeasure();
     });
   };
 
@@ -94,20 +132,16 @@ class FillSpace extends Component {
     if (this.observer) {
       this.observer.disconnect();
     }
-
-    this.observer = new ResizeObserver(() => this._measure());
-
-    // Only observe the referenced elements + the rendered content — never the
-    // spacer's own parent, since resizing the spacer would resize the parent
+    this.observer = new ResizeObserver(() => this._onViewportChange());
     const { aboveRef, belowRef, containerRef } = this.props;
     const aboveList = Array.isArray(aboveRef) ? aboveRef : [aboveRef];
     const belowList = Array.isArray(belowRef) ? belowRef : [belowRef];
-    const containerTarget = containerRef && 'current' in containerRef ? containerRef.current : containerRef;
+    const containerTarget =
+      containerRef && 'current' in containerRef ? containerRef.current : containerRef;
     const targets = [
       ...aboveList.map((r) => (r && 'current' in r ? r.current : r)),
       ...belowList.map((r) => (r && 'current' in r ? r.current : r)),
       containerTarget,
-      this.contentRef,
     ];
     for (const el of targets) {
       if (el && el.offsetParent !== null) {
@@ -116,162 +150,201 @@ class FillSpace extends Component {
     }
   }
 
-  measure = () => {
-    this._measure();
+  probeMeasure = () => {
+    this._probeMeasure();
   };
 
-  _measure() {
-    if (!this.ref) return;
+  viewportMeasure = () => {
+    this._viewportMeasure();
+  };
 
-    const {
-      belowRef,
-      containerRef,
-      measureElement,
-      measureGap = 0,
-      minHeight = 0,
-      maxHeight,
-      onMeasurement,
-    } = this.props;
+  measure = () => {
+    this._probeMeasure();
+    this._viewportMeasure();
+  };
 
-    // Distance from the document top to the spacer top — includes every
-    // element above the spacer plus their margins and the parent's padding.
-    // Document-relative (rect.top + scrollY), so scrolling the page does not
-    // change the computed height (fixes "grows with scrolling").
-    const rect = this.ref.getBoundingClientRect();
-    const abovePx = rect.top + window.scrollY;
-
-    // Height to reserve for the footer below (its box + top margin).
-    const belowEl = belowRef?.current;
-    let belowPx = 0;
-    if (belowEl && belowEl.offsetParent !== null) {
-      belowPx = belowEl.offsetHeight;
-      const marginTop = parseFloat(window.getComputedStyle(belowEl).marginTop);
-      belowPx += Number.isFinite(marginTop) ? marginTop : 0;
+  /** Only measures the height of the `renderItem` probe. Nothing else. */
+  _probeMeasure() {
+    const h = this.probeRef?.offsetHeight;
+    if (h > 0 && h !== this.state.unitHeight) {
+      this.setState({ unitHeight: h }, () => this._viewportMeasure());
     }
+  }
 
-    const containerEl = containerRef && 'current' in containerRef ? containerRef.current : containerRef;
+  /** Viewport height minus above/below refs: free space for the list. */
+  _viewportMeasure() {
+    if (!this.ref) return;
+    const { belowRef, containerRef, reserveBottom = 0, minPageSize } = this.props;
+    const rect = this.ref.getBoundingClientRect();
+    let belowPx = Number(reserveBottom) || 0;
+    const belowList = Array.isArray(belowRef) ? belowRef : [belowRef];
+    for (const ref of belowList) {
+      const el = ref && 'current' in ref ? ref.current : ref;
+      if (el && el.offsetParent !== null) {
+        belowPx += el.offsetHeight;
+        const mt = parseFloat(window.getComputedStyle(el).marginTop);
+        if (Number.isFinite(mt)) belowPx += mt;
+      }
+    }
+    const containerEl =
+      containerRef && 'current' in containerRef ? containerRef.current : containerRef;
     let available;
     if (containerEl && typeof containerEl.getBoundingClientRect === 'function') {
       const cRect = containerEl.getBoundingClientRect();
       const paddingBottom = parseFloat(window.getComputedStyle(containerEl).paddingBottom) || 0;
       available = Math.max(0, cRect.bottom - rect.top - belowPx - paddingBottom);
     } else {
-      available = Math.max(0, window.innerHeight - abovePx - belowPx);
+      available = Math.max(0, window.innerHeight - rect.top - belowPx);
     }
-
-    const clamped = Math.min(
-      Math.max(available, minHeight),
-      maxHeight ?? Infinity,
-    );
-
-    // Height of the real rendered children (the top part of the spacer).
-    let contentHeight = 0;
-    if (this.contentRef) {
-      contentHeight = this.contentRef.offsetHeight;
-    }
-
-    // Measure the height of one measurement unit from the hidden copy so the
-    // repeats match the real rendered size.
-    let unitHeight = this.state.unitHeight;
-    if (measureElement != null && this.unitRef) {
-      const h = this.unitRef.offsetHeight;
-      if (h > 0) unitHeight = h;
-    }
-
-    // How many units would fit in the WHOLE spacer height, as if there were
-    // no children — this is what onMeasurement reports.
-    let totalCount = 0;
-    // How many units actually fit in the leftover space below the children —
-    // this is what gets rendered. Starts at 0: if the content already fills
-    // the space, none fit.
-    let fillCount = 0;
-    if (measureElement != null && unitHeight > 0) {
-      totalCount = Math.floor((clamped + measureGap) / (unitHeight + measureGap));
-      const fillHeight = Math.max(0, clamped - contentHeight);
-      fillCount = Math.floor((fillHeight + measureGap) / (unitHeight + measureGap));
-    }
-
-    // Fire onMeasurement with the TOTAL count whenever it changes — including
-    // the first measurement. lastTotalCount starts as null so the initial
-    // value (even 0) is always reported once.
+    const minSize = Math.max(1, Number(minPageSize) || 10);
+    const { unitHeight } = this.state;
+    const nextPageSize =
+      unitHeight > 0 ? Math.max(minSize, Math.floor(available / unitHeight)) : minSize;
     if (
-      measureElement != null &&
-      typeof onMeasurement === 'function' &&
-      totalCount !== this.lastTotalCount
+      available !== this.state.viewportHeight ||
+      nextPageSize !== this.state.pageSize
     ) {
-      this.lastTotalCount = totalCount;
-      onMeasurement(totalCount);
-    }
-
-    if (
-      Math.abs(clamped - this.state.height) > 0.5 ||
-      Math.abs(unitHeight - this.state.unitHeight) > 0.5 ||
-      Math.abs(contentHeight - this.state.contentHeight) > 0.5 ||
-      totalCount !== this.state.totalCount ||
-      fillCount !== this.state.fillCount
-    ) {
-      this.setState({ height: clamped, unitHeight, contentHeight, totalCount, fillCount });
+      this.setState({ viewportHeight: available, pageSize: nextPageSize });
     }
   }
 
+  _handleWheel = (event) => {
+    const { items } = this.props;
+    if (!Array.isArray(items)) return;
+    const { pageSize, currentPage } = this.state;
+    const pageCount = Math.max(1, Math.ceil(items.length / Math.max(1, pageSize)));
+    const delta = event.deltaY || 0;
+    if (pageCount <= 1) return;
+    if (delta === 0) return;
+    if (Math.sign(delta) !== Math.sign(this.wheelAcc || 0)) this.wheelAcc = 0;
+    this.wheelAcc = (this.wheelAcc || 0) + delta;
+    const threshold = Math.max(50, 800 / pageCount);
+    if (Math.abs(this.wheelAcc) < threshold) return;
+    const dir = this.wheelAcc > 0 ? 1 : -1;
+    this.wheelAcc = 0;
+    const next = dir > 0
+      ? Math.min(pageCount, currentPage + 1)
+      : Math.max(1, currentPage - 1);
+    if (next === currentPage) return;
+    this._goToPage(next);
+  };
+
+  _goToPage = (page) => {
+    const { items, onPageChange } = this.props;
+    const total = Array.isArray(items) ? items.length : 0;
+    const pageCount = Math.max(1, Math.ceil(total / Math.max(1, this.state.pageSize)));
+    const next = Math.min(Math.max(1, Number(page) || 1), pageCount);
+    if (next === this.state.currentPage) return;
+    this.setState({ currentPage: next });
+    onPageChange?.(next);
+  };
+
   render() {
     const {
+      // Discarded legacy layout props (kept here so they don't leak to the DOM).
       aboveRef,
       belowRef,
-      onMeasurement,
-      minHeight = 0,
+      containerRef,
+      reserveBottom,
+      minHeight,
       maxHeight,
+      minPageSize,
+      onPageChange,
+      onWheel,
       debug = false,
-      children,
-      measureElement,
-      measureGap = 0,
+      items,
+      renderItem,
       sx,
       ...rest
     } = this.props;
 
-    const { height, fillCount } = this.state;
-
-    // Repeated measurement units fill only the leftover space below the real
-    // children. fillCount (computed in _measure) starts at 0: if the content
-    // already fills the space, no units are rendered.
-    let fill = null;
-    if (measureElement != null) {
-      const items = [];
-      for (let i = 0; i < fillCount; i++) {
-        items.push(
-          <Box key={i} sx={{ width: '100%' }}>
-            {measureElement}
-          </Box>,
-        );
-      }
-      fill = (
-        <Box
-          sx={{
-            display: 'flex',
-            flexDirection: 'column',
-            gap: measureGap,
-            width: '100%',
-            overflow: 'hidden',
-          }}
-        >
-          {items}
-        </Box>
-      );
-    }
+    // FillSpace owns current page, wheel-pagination and the pagination header.
+    // Caller feeds `items` plus one row element via `renderItem` (component
+    // type or callback).
+    const { pageSize, currentPage, viewportHeight } = this.state;
+    const total = items.length;
+    const pageCount = Math.max(1, Math.ceil(total / Math.max(1, pageSize)));
+    const safePage = Math.min(Math.max(1, currentPage), pageCount);
+    const offset = (safePage - 1) * pageSize;
+    const pageItems = items.slice(offset, offset + pageSize);
+    const showPagination = total > pageSize;
+    // Hidden data-free probe: measures `renderItem` itself (no data).
+    const probe = renderProbeElement(renderItem);
 
     return (
       <>
+        <Box
+          // Fixed single-line bar: the header height must not depend on the
+          // page count. Otherwise the first fit (e.g. "1-17") pushes the
+          // spacer down, the available height shrinks, and a second pass
+          // flips to "1-15". One pass: constant 44px, real values always
+          // rendered (only visibility is gated), no placeholder numbers.
+          sx={{ mb: 1, height: 44, overflow: 'hidden' }}
+        >
+          <Box
+            aria-hidden={!showPagination || undefined}
+            sx={{
+              display: 'flex',
+              justifyContent: 'space-between',
+              alignItems: 'center',
+              flexWrap: 'nowrap',
+              gap: 1,
+              width: '100%',
+              height: 44,
+              visibility: showPagination ? 'visible' : 'hidden',
+              pointerEvents: showPagination ? 'auto' : 'none',
+            }}
+          >
+            <Typography
+              variant="body2"
+              color="text.secondary"
+              noWrap
+              sx={{ flexShrink: 1, minWidth: 0, overflow: 'hidden', textOverflow: 'ellipsis' }}
+            >
+              {total === 0 ? '0' : `${offset + 1}–${Math.min(offset + pageSize, total)}`} von{' '}
+              {total}
+            </Typography>
+            <Pagination
+              count={pageCount}
+              page={safePage}
+              onChange={(_e, page) => this._goToPage(page)}
+              color="primary"
+              size="large"
+              onMouseDown={(e) => e.preventDefault()}
+              sx={{
+                flexShrink: 0,
+                maxWidth: '100%',
+                overflowX: 'auto',
+                scrollbarWidth: 'none',
+                '&::-webkit-scrollbar': { display: 'none' },
+                '& .MuiPagination-ul': { flexWrap: 'nowrap' },
+                '& .MuiPaginationItem-root': {
+                  minWidth: 44,
+                  height: 44,
+                  fontSize: '1rem',
+                },
+              }}
+            />
+          </Box>
+        </Box>
         <Box
           ref={(el) => {
             this.ref = el;
           }}
+          onWheel={(e) => {
+            this._handleWheel(e);
+            onWheel?.(e);
+          }}
           {...rest}
           sx={[
             {
               position: 'relative',
-              height,
-              minHeight,
-              ...(maxHeight != null ? { maxHeight } : {}),
+              height: viewportHeight ?? 'auto',
+              overflow: 'hidden',
+              width: '100%',
+              // Keep wheel ticks from scrolling the page behind the list.
+              // (No preventDefault needed — React wheel is passive.)
+              overscrollBehavior: 'contain',
             },
             debug
               ? (theme) => ({
@@ -281,21 +354,19 @@ class FillSpace extends Component {
             sx,
           ]}
         >
-          {children != null ? (
+          <Box sx={{ width: '100%' }}>
+            <List dense disablePadding sx={{ width: '100%' }}>
+              {pageItems.map((item, i) => (
+                <Box key={item?.id ?? offset + i} data-fill-row sx={{ width: '100%' }}>
+                  {renderRowElement(renderItem, item, offset + i)}
+                </Box>
+              ))}
+            </List>
+          </Box>
+          {probe != null ? (
             <Box
               ref={(el) => {
-                this.contentRef = el;
-              }}
-              sx={{ width: '100%', ...(measureElement == null ? { height: '100%' } : {}) }}
-            >
-              {children}
-            </Box>
-          ) : null}
-          {fill}
-          {measureElement != null ? (
-            <Box
-              ref={(el) => {
-                this.unitRef = el;
+                this.probeRef = el;
               }}
               aria-hidden
               sx={{
@@ -307,7 +378,11 @@ class FillSpace extends Component {
                 pointerEvents: 'none',
               }}
             >
-              {measureElement}
+              <List dense disablePadding sx={{ width: '100%' }}>
+                <Box data-fill-row sx={{ width: '100%' }}>
+                  {probe}
+                </Box>
+              </List>
             </Box>
           ) : null}
         </Box>