[DataGridPro] Fix onRowsScrollEnd being triggered instantly when us…

…ing a bottom pinned row (#14602)

packages/x-data-grid-pro/src/tests/infiniteLoader.DataGridPro.test.tsx

@@ -160,4 +160,52 @@ describe('<DataGridPro /> - Infnite loader', () => {
     // should not load more rows because the threshold is not reached
     expect(getRow.callCount).to.equal(5);
   });
+
+  it('should not call `onRowsScrollEnd` if there are rows pinned to the bottom and the viewport scroll is at the top', async function test() {
+    if (isJSDOM) {
+      this.skip(); // Needs layout
+    }
+    const baseRows = [
+      { id: 0, brand: 'Nike' },
+      { id: 1, brand: 'Adidas' },
+      { id: 2, brand: 'Puma' },
+      { id: 3, brand: 'Under Armor' },
+      { id: 4, brand: 'Jordan' },
+      { id: 5, brand: 'Reebok' },
+    ];
+    const basePinnedRows = {
+      bottom: [{ id: 6, brand: 'Unbranded' }],
+    };
+
+    const handleRowsScrollEnd = spy();
+    function TestCase({
+      rows,
+      pinnedRows,
+    }: {
+      rows: typeof baseRows;
+      pinnedRows: typeof basePinnedRows;
+    }) {
+      return (
+        <div style={{ width: 300, height: 300 }}>
+          <DataGridPro
+            columns={[{ field: 'brand', width: 100 }]}
+            rows={rows}
+            onRowsScrollEnd={handleRowsScrollEnd}
+            pinnedRows={pinnedRows}
+          />
+        </div>
+      );
+    }
+    const { container } = render(<TestCase rows={baseRows} pinnedRows={basePinnedRows} />);
+    const virtualScroller = container.querySelector('.MuiDataGrid-virtualScroller')!;
+    await sleep(1);
+    // after initial render and a scroll event that did not reach the bottom of the grid
+    // the `onRowsScrollEnd` should not be called
+    expect(handleRowsScrollEnd.callCount).to.equal(0);
+    // arbitrary number to make sure that the bottom of the grid window is reached.
+    virtualScroller.scrollTop = 12345;
+    virtualScroller.dispatchEvent(new Event('scroll'));
+    await sleep(1);
+    expect(handleRowsScrollEnd.callCount).to.equal(1);
+  });
 });

packages/x-data-grid/src/hooks/features/virtualization/useGridVirtualScroller.tsx

@@ -503,7 +503,7 @@ export const useGridVirtualScroller = () => {
       if (panel) {
         rows.push(panel);
       }
-      if (isLastVisible) {
+      if (params.position === undefined && isLastVisibleInSection) {
         rows.push(apiRef.current.getInfiniteLoadingTriggerElement?.({ lastRowId: id }));
       }
     });