handle updates while outputs are collapsed (microsoft#204201)

* handle updates while outputs are collapsed

* naming, comments

Author: amunger

src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts

@@ -2830,7 +2830,7 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditorD
 
 	async updateOutput(cell: CodeCellViewModel, output: IInsetRenderOutput, offset: number): Promise<void> {
 		this._insetModifyQueueByOutputId.queue(output.source.model.outputId, async () => {
-			if (this._isDisposed || !this._webview) {
+			if (this._isDisposed || !this._webview || cell.isOutputCollapsed) {
 				return;
 			}
 

src/vs/workbench/contrib/notebook/browser/view/cellParts/cellOutput.ts

@@ -183,6 +183,7 @@ class CellOutputElement extends Disposable {
 		const index = this.viewCell.outputsViewModels.indexOf(this.output);
 
 		if (this.viewCell.isOutputCollapsed || !this.notebookEditor.hasModel()) {
+			this.cellOutputContainer.flagAsStale();
 			return undefined;
 		}
 
@@ -477,6 +478,7 @@ const enum CellOutputUpdateContext {
 
 export class CellOutputContainer extends CellContentPart {
 	private _outputEntries: OutputEntryViewHandler[] = [];
+	private _hasStaleOutputs: boolean = false;
 
 	get renderedOutputEntries() {
 		return this._outputEntries;
@@ -534,6 +536,13 @@ export class CellOutputContainer extends CellContentPart {
 		}
 	}
 
+	/**
+	 * Notify that an output may have been swapped out without the model getting rendered.
+	 */
+	flagAsStale() {
+		this._hasStaleOutputs = true;
+	}
+
 	private _doRender() {
 		if (this.viewCell.outputsViewModels.length > 0) {
 			if (this.viewCell.layoutInfo.outputTotalHeight !== 0) {
@@ -569,6 +578,13 @@ export class CellOutputContainer extends CellContentPart {
 	}
 
 	viewUpdateShowOutputs(initRendering: boolean): void {
+		if (this._hasStaleOutputs) {
+			this._hasStaleOutputs = false;
+			this._outputEntries.forEach(entry => {
+				entry.element.rerender();
+			});
+		}
+
 		for (let index = 0; index < this._outputEntries.length; index++) {
 			const viewHandler = this._outputEntries[index];
 			const outputEntry = viewHandler.element;