From adaaf21b4c01dc0856a1659e4da5746249a2520d Mon Sep 17 00:00:00 2001
From: Ivaylo Pavlov <ivailo90@gmail.com>
Date: Mon, 17 Feb 2025 17:46:20 +0000
Subject: [PATCH] [lexical-table] Freeze top row using pure CSS (#7190)

---
 .../plugins/TableActionMenuPlugin/index.tsx   | 20 +++++++++++
 .../src/themes/PlaygroundEditorTheme.css      | 28 +++++++++++++++
 .../src/themes/PlaygroundEditorTheme.ts       |  1 +
 .../lexical-table/src/LexicalTableNode.ts     | 36 +++++++++++++++++++
 .../__tests__/unit/LexicalTableNode.test.tsx  |  1 +
 5 files changed, 86 insertions(+)

diff --git a/packages/lexical-playground/src/plugins/TableActionMenuPlugin/index.tsx b/packages/lexical-playground/src/plugins/TableActionMenuPlugin/index.tsx
index 9df7c6355f5..46096a69ec6 100644
--- a/packages/lexical-playground/src/plugins/TableActionMenuPlugin/index.tsx
+++ b/packages/lexical-playground/src/plugins/TableActionMenuPlugin/index.tsx
@@ -516,6 +516,19 @@ function TableActionMenu({
     });
   }, [editor, tableCellNode, clearTableSelection, onClose]);
 
+  const toggleFirstRowFreeze = useCallback(() => {
+    editor.update(() => {
+      if (tableCellNode.isAttached()) {
+        const tableNode = $getTableNodeFromLexicalNodeOrThrow(tableCellNode);
+        if (tableNode) {
+          tableNode.setFrozenRows(tableNode.getFrozenRows() === 0 ? 1 : 0);
+        }
+      }
+      clearTableSelection();
+      onClose();
+    });
+  }, [editor, tableCellNode, clearTableSelection, onClose]);
+
   const toggleFirstColumnFreeze = useCallback(() => {
     editor.update(() => {
       if (tableCellNode.isAttached()) {
@@ -670,6 +683,13 @@ function TableActionMenu({
           </div>
         </DropDownItem>
       </DropDown>
+      <button
+        type="button"
+        className="item"
+        onClick={() => toggleFirstRowFreeze()}
+        data-test-id="table-freeze-first-row">
+        <span className="text">Toggle First Row Freeze</span>
+      </button>
       <button
         type="button"
         className="item"
diff --git a/packages/lexical-playground/src/themes/PlaygroundEditorTheme.css b/packages/lexical-playground/src/themes/PlaygroundEditorTheme.css
index 8baa88942e7..f2de4131c83 100644
--- a/packages/lexical-playground/src/themes/PlaygroundEditorTheme.css
+++ b/packages/lexical-playground/src/themes/PlaygroundEditorTheme.css
@@ -221,6 +221,34 @@
   margin-top: 25px;
   margin-bottom: 30px;
 }
+.PlaygroundEditorTheme__tableFrozenRow {
+  /* position:sticky needs overflow:clip or visible
+     https://github.com/w3c/csswg-drafts/issues/865#issuecomment-350585274 */
+  overflow-x: clip;
+}
+.PlaygroundEditorTheme__tableFrozenRow tr:nth-of-type(1) > td {
+  overflow: clip;
+  background-color: #ffffff;
+  position: sticky;
+  z-index: 2;
+  top: 44px;
+}
+.PlaygroundEditorTheme__tableFrozenRow tr:nth-of-type(1) > th {
+  overflow: clip;
+  background-color: #f2f3f5;
+  position: sticky;
+  z-index: 2;
+  top: 44px;
+}
+.PlaygroundEditorTheme__tableFrozenRow tr:nth-of-type(1) > th:after,
+.PlaygroundEditorTheme__tableFrozenRow tr:nth-of-type(1) > td:after {
+  content: '';
+  position: absolute;
+  left: 0;
+  bottom: 0;
+  width: 100%;
+  border-bottom: 1px solid #bbb;
+}
 .PlaygroundEditorTheme__tableFrozenColumn tr > td:first-child {
   background-color: #ffffff;
   position: sticky;
diff --git a/packages/lexical-playground/src/themes/PlaygroundEditorTheme.ts b/packages/lexical-playground/src/themes/PlaygroundEditorTheme.ts
index c4c831d7292..16a17fbc47e 100644
--- a/packages/lexical-playground/src/themes/PlaygroundEditorTheme.ts
+++ b/packages/lexical-playground/src/themes/PlaygroundEditorTheme.ts
@@ -105,6 +105,7 @@ const theme: EditorThemeClasses = {
   tableCellResizer: 'PlaygroundEditorTheme__tableCellResizer',
   tableCellSelected: 'PlaygroundEditorTheme__tableCellSelected',
   tableFrozenColumn: 'PlaygroundEditorTheme__tableFrozenColumn',
+  tableFrozenRow: 'PlaygroundEditorTheme__tableFrozenRow',
   tableRowStriping: 'PlaygroundEditorTheme__tableRowStriping',
   tableScrollableWrapper: 'PlaygroundEditorTheme__tableScrollableWrapper',
   tableSelected: 'PlaygroundEditorTheme__tableSelected',
diff --git a/packages/lexical-table/src/LexicalTableNode.ts b/packages/lexical-table/src/LexicalTableNode.ts
index 9d1a24c4187..3d23d90bbe6 100644
--- a/packages/lexical-table/src/LexicalTableNode.ts
+++ b/packages/lexical-table/src/LexicalTableNode.ts
@@ -49,6 +49,7 @@ export type SerializedTableNode = Spread<
     colWidths?: readonly number[];
     rowStriping?: boolean;
     frozenColumnCount?: number;
+    frozenRowCount?: number;
   },
   SerializedElementNode
 >;
@@ -103,6 +104,20 @@ function setFrozenColumns(
   }
 }
 
+function setFrozenRows(
+  dom: HTMLElement,
+  config: EditorConfig,
+  frozenRowCount: number,
+): void {
+  if (frozenRowCount > 0) {
+    addClassNamesToElement(dom, config.theme.tableFrozenRow);
+    dom.setAttribute('data-lexical-frozen-row', 'true');
+  } else {
+    removeClassNamesFromElement(dom, config.theme.tableFrozenRow);
+    dom.removeAttribute('data-lexical-frozen-row');
+  }
+}
+
 function alignTableElement(
   dom: HTMLElement,
   config: EditorConfig,
@@ -153,6 +168,7 @@ export class TableNode extends ElementNode {
   /** @internal */
   __rowStriping: boolean;
   __frozenColumnCount: number;
+  __frozenRowCount: number;
   __colWidths?: readonly number[];
 
   static getType(): string {
@@ -181,6 +197,7 @@ export class TableNode extends ElementNode {
     this.__colWidths = prevNode.__colWidths;
     this.__rowStriping = prevNode.__rowStriping;
     this.__frozenColumnCount = prevNode.__frozenColumnCount;
+    this.__frozenRowCount = prevNode.__frozenRowCount;
   }
 
   static importDOM(): DOMConversionMap | null {
@@ -201,6 +218,7 @@ export class TableNode extends ElementNode {
       .updateFromJSON(serializedNode)
       .setRowStriping(serializedNode.rowStriping || false)
       .setFrozenColumns(serializedNode.frozenColumnCount || 0)
+      .setFrozenRows(serializedNode.frozenRowCount || 0)
       .setColWidths(serializedNode.colWidths);
   }
 
@@ -208,6 +226,7 @@ export class TableNode extends ElementNode {
     super(key);
     this.__rowStriping = false;
     this.__frozenColumnCount = 0;
+    this.__frozenRowCount = 0;
   }
 
   exportJSON(): SerializedTableNode {
@@ -217,6 +236,7 @@ export class TableNode extends ElementNode {
       frozenColumnCount: this.__frozenColumnCount
         ? this.__frozenColumnCount
         : undefined,
+      frozenRowCount: this.__frozenRowCount ? this.__frozenRowCount : undefined,
       rowStriping: this.__rowStriping ? this.__rowStriping : undefined,
     };
   }
@@ -259,6 +279,9 @@ export class TableNode extends ElementNode {
     if (this.__frozenColumnCount) {
       setFrozenColumns(tableElement, config, this.__frozenColumnCount);
     }
+    if (this.__frozenRowCount) {
+      setFrozenRows(tableElement, config, this.__frozenRowCount);
+    }
     if (this.__rowStriping) {
       setRowStriping(tableElement, config, true);
     }
@@ -284,6 +307,9 @@ export class TableNode extends ElementNode {
     if (prevNode.__frozenColumnCount !== this.__frozenColumnCount) {
       setFrozenColumns(dom, config, this.__frozenColumnCount);
     }
+    if (prevNode.__frozenRowCount !== this.__frozenRowCount) {
+      setFrozenRows(dom, config, this.__frozenRowCount);
+    }
     updateColgroup(dom, config, this.getColumnCount(), this.getColWidths());
     alignTableElement(
       this.getDOMSlot(dom).element,
@@ -510,6 +536,16 @@ export class TableNode extends ElementNode {
     return this.getLatest().__frozenColumnCount;
   }
 
+  setFrozenRows(rowCount: number): this {
+    const self = this.getWritable();
+    self.__frozenRowCount = rowCount;
+    return self;
+  }
+
+  getFrozenRows(): number {
+    return this.getLatest().__frozenRowCount;
+  }
+
   canSelectBefore(): true {
     return true;
   }
diff --git a/packages/lexical-table/src/__tests__/unit/LexicalTableNode.test.tsx b/packages/lexical-table/src/__tests__/unit/LexicalTableNode.test.tsx
index 697007a8d5d..21da9a230d9 100644
--- a/packages/lexical-table/src/__tests__/unit/LexicalTableNode.test.tsx
+++ b/packages/lexical-table/src/__tests__/unit/LexicalTableNode.test.tsx
@@ -78,6 +78,7 @@ const editorConfig = Object.freeze({
       right: 'test-table-alignment-right',
     },
     tableFrozenColumn: 'test-table-frozen-column-class',
+    tableFrozenRow: 'test-table-frozen-row-class',
     tableRowStriping: 'test-table-row-striping-class',
     tableScrollableWrapper: 'table-scrollable-wrapper',
   },