Add resizable columns to rich text tables

Author: beNative

components/RichTextEditor.tsx

@@ -63,6 +63,7 @@ import {
   $createRangeSelection,
   $createTextNode,
   $getNodeByKey,
+  $nodesOfType,
   $setSelection,
 } from 'lexical';
 import {
@@ -198,6 +199,8 @@ const RICH_TEXT_THEME = {
 
 const Placeholder: React.FC = () => null;
 
+const MIN_COLUMN_WIDTH = 72;
+
 const normalizeUrl = (url: string): string => {
   const trimmed = url.trim();
   if (!trimmed) {
@@ -271,6 +274,199 @@ const LinkModal: React.FC<{
   );
 };
 
+const ensureColGroupWithWidths = (tableElement: HTMLTableElement): HTMLTableColElement[] => {
+  const firstRow = tableElement.rows[0];
+  const columnCount = firstRow?.cells.length ?? 0;
+  if (columnCount === 0) {
+    return [];
+  }
+
+  let colGroup = tableElement.querySelector('colgroup');
+  if (!colGroup) {
+    colGroup = document.createElement('colgroup');
+    tableElement.insertBefore(colGroup, tableElement.firstChild);
+  }
+
+  while (colGroup.children.length < columnCount) {
+    const col = document.createElement('col');
+    colGroup.appendChild(col);
+  }
+
+  while (colGroup.children.length > columnCount) {
+    colGroup.lastElementChild?.remove();
+  }
+
+  const colElements = Array.from(colGroup.children) as HTMLTableColElement[];
+  const existingWidths = colElements.map(col => parseFloat(col.style.width || ''));
+  const needInitialization = existingWidths.some(width => Number.isNaN(width) || width <= 0);
+
+  if (needInitialization) {
+    const columnWidths = Array.from(firstRow.cells).map(cell => cell.getBoundingClientRect().width || MIN_COLUMN_WIDTH);
+    colElements.forEach((col, index) => {
+      const width = Math.max(MIN_COLUMN_WIDTH, columnWidths[index] ?? MIN_COLUMN_WIDTH);
+      col.style.width = `${width}px`;
+    });
+  }
+
+  return colElements;
+};
+
+const attachColumnResizeHandles = (tableElement: HTMLTableElement): (() => void) => {
+  const container = tableElement.parentElement ?? tableElement;
+  const originalContainerPosition = container.style.position;
+  const restoreContainerPosition = originalContainerPosition === '' && getComputedStyle(container).position === 'static';
+
+  if (restoreContainerPosition) {
+    container.style.position = 'relative';
+  }
+
+  tableElement.style.tableLayout = 'fixed';
+
+  const overlay = document.createElement('div');
+  overlay.style.position = 'absolute';
+  overlay.style.inset = '0';
+  overlay.style.pointerEvents = 'none';
+  overlay.style.zIndex = '10';
+  container.appendChild(overlay);
+
+  const cleanupHandles: Array<() => void> = [];
+  const resizeObserver = new ResizeObserver(() => renderHandles());
+
+  function renderHandles() {
+    overlay.replaceChildren();
+
+    const firstRow = tableElement.rows[0];
+    if (!firstRow) {
+      return;
+    }
+
+    const cols = ensureColGroupWithWidths(tableElement);
+    const containerRect = container.getBoundingClientRect();
+    const cells = Array.from(firstRow.cells);
+
+    cells.forEach((cell, columnIndex) => {
+      if (columnIndex === cells.length - 1) {
+        return;
+      }
+
+      const cellRect = cell.getBoundingClientRect();
+      const handle = document.createElement('div');
+      handle.setAttribute('role', 'presentation');
+      handle.contentEditable = 'false';
+      handle.style.position = 'absolute';
+      handle.style.top = `${tableElement.offsetTop}px`;
+      handle.style.left = `${cellRect.right - containerRect.left - 3}px`;
+      handle.style.width = '6px';
+      handle.style.height = `${tableElement.offsetHeight}px`;
+      handle.style.cursor = 'col-resize';
+      handle.style.pointerEvents = 'auto';
+      handle.style.userSelect = 'none';
+
+      let startX = 0;
+      let leftWidth = 0;
+      let rightWidth = 0;
+
+      const handleMouseMove = (event: MouseEvent) => {
+        const deltaX = event.clientX - startX;
+        const nextLeftWidth = Math.max(MIN_COLUMN_WIDTH, leftWidth + deltaX);
+        const nextRightWidth = Math.max(MIN_COLUMN_WIDTH, rightWidth - deltaX);
+
+        cols[columnIndex].style.width = `${nextLeftWidth}px`;
+        cols[columnIndex + 1].style.width = `${nextRightWidth}px`;
+      };
+
+      const handleMouseUp = () => {
+        document.removeEventListener('mousemove', handleMouseMove);
+        document.removeEventListener('mouseup', handleMouseUp);
+      };
+
+      const handleMouseDown = (event: MouseEvent) => {
+        event.preventDefault();
+        startX = event.clientX;
+        leftWidth = parseFloat(cols[columnIndex].style.width || `${cell.offsetWidth}`);
+        rightWidth = parseFloat(
+          cols[columnIndex + 1].style.width || `${cells[columnIndex + 1]?.offsetWidth ?? MIN_COLUMN_WIDTH}`,
+        );
+
+        document.addEventListener('mousemove', handleMouseMove);
+        document.addEventListener('mouseup', handleMouseUp);
+      };
+
+      handle.addEventListener('mousedown', handleMouseDown);
+      cleanupHandles.push(() => handle.removeEventListener('mousedown', handleMouseDown));
+      overlay.appendChild(handle);
+    });
+  }
+
+  resizeObserver.observe(tableElement);
+  renderHandles();
+
+  return () => {
+    cleanupHandles.forEach(cleanup => cleanup());
+    resizeObserver.disconnect();
+    overlay.remove();
+
+    if (restoreContainerPosition) {
+      container.style.position = originalContainerPosition;
+    }
+  };
+};
+
+const TableColumnResizePlugin: React.FC = () => {
+  const [editor] = useLexicalComposerContext();
+
+  useEffect(() => {
+    const cleanupMap = new Map<string, () => void>();
+
+    const cleanupTable = (key: string) => {
+      const cleanup = cleanupMap.get(key);
+      if (cleanup) {
+        cleanup();
+        cleanupMap.delete(key);
+      }
+    };
+
+    const initializeTable = (tableNode: TableNode) => {
+      const tableKey = tableNode.getKey();
+      const tableElement = editor.getElementByKey(tableKey);
+      if (tableElement instanceof HTMLTableElement) {
+        cleanupTable(tableKey);
+        cleanupMap.set(tableKey, attachColumnResizeHandles(tableElement));
+      }
+    };
+
+    editor.getEditorState().read(() => {
+      const tableNodes = $nodesOfType(TableNode);
+      tableNodes.forEach(tableNode => {
+        initializeTable(tableNode);
+      });
+    });
+
+    const unregisterMutationListener = editor.registerMutationListener(TableNode, mutations => {
+      editor.getEditorState().read(() => {
+        mutations.forEach((mutation, key) => {
+          if (mutation === 'created') {
+            const tableNode = $getNodeByKey<TableNode>(key);
+            if (tableNode) {
+              initializeTable(tableNode);
+            }
+          } else if (mutation === 'destroyed') {
+            cleanupTable(key);
+          }
+        });
+      });
+    });
+
+    return () => {
+      unregisterMutationListener();
+      cleanupMap.forEach(cleanup => cleanup());
+      cleanupMap.clear();
+    };
+  }, [editor]);
+
+  return null;
+};
+
 const TableModal: React.FC<{
   isOpen: boolean;
   onClose: () => void;
@@ -1912,6 +2108,7 @@ const RichTextEditor = forwardRef<RichTextEditorHandle, RichTextEditorProps>(
           <HistoryPlugin />
           {!readOnly && <AutoFocusPlugin />}
           <TablePlugin hasCellMerge={true} hasCellBackgroundColor={true} hasTabHandler={true} />
+          {!readOnly && <TableColumnResizePlugin />}
           <ListPlugin />
           <LinkPlugin />
           <ImagePlugin />