splitview: use preferred size in onDidChange

src/vs/base/browser/ui/splitview/panelview.ts

@@ -35,8 +35,8 @@ export abstract class Panel implements IView {
 	private static HEADER_SIZE = 22;
 
 	protected _expanded: boolean;
+	private expandedSize: number | undefined = undefined;
 	private _headerVisible = true;
-	private _onDidChange = new Emitter<void>();
 	private _minimumBodySize: number;
 	private _maximumBodySize: number;
 	private ariaHeaderLabel: string;
@@ -46,6 +46,9 @@ export abstract class Panel implements IView {
 	private header: HTMLElement;
 	protected disposables: IDisposable[] = [];
 
+	private _onDidChange = new Emitter<number | undefined>();
+	readonly onDidChange: Event<number | undefined> = this._onDidChange.event;
+
 	get draggableElement(): HTMLElement {
 		return this.header;
 	}
@@ -97,8 +100,6 @@ export abstract class Panel implements IView {
 		return headerSize + maximumBodySize;
 	}
 
-	readonly onDidChange: Event<void> = this._onDidChange.event;
-
 	constructor(options: IPanelOptions = {}) {
 		this._expanded = typeof options.expanded === 'undefined' ? true : !!options.expanded;
 		this.ariaHeaderLabel = options.ariaHeaderLabel || '';
@@ -117,7 +118,7 @@ export abstract class Panel implements IView {
 
 		this._expanded = !!expanded;
 		this.updateHeader();
-		this._onDidChange.fire();
+		this._onDidChange.fire(expanded ? this.expandedSize : undefined);
 	}
 
 	get headerVisible(): boolean {
@@ -179,6 +180,10 @@ export abstract class Panel implements IView {
 	layout(size: number): void {
 		const headerSize = this.headerVisible ? Panel.HEADER_SIZE : 0;
 		this.layoutBody(size - headerSize);
+
+		if (this.isExpanded()) {
+			this.expandedSize = size;
+		}
 	}
 
 	style(styles: IPanelStyles): void {

src/vs/base/browser/ui/splitview/splitview2.ts

@@ -22,7 +22,7 @@ export interface ISplitViewOptions {
 export interface IView {
 	readonly minimumSize: number;
 	readonly maximumSize: number;
-	readonly onDidChange: Event<void>;
+	readonly onDidChange: Event<number | undefined>;
 	render(container: HTMLElement, orientation: Orientation): void;
 	layout(size: number, orientation: Orientation): void;
 }
@@ -87,7 +87,7 @@ export class SplitView implements IDisposable {
 			this.el.insertBefore(container, this.el.children.item(index));
 		}
 
-		const onChangeDisposable = mapEvent(view.onDidChange, () => item)(this.onViewChange, this);
+		const onChangeDisposable = view.onDidChange(size => this.onViewChange(item, size));
 		const containerDisposable = toDisposable(() => this.el.removeChild(container));
 		const disposable = combinedDisposable([onChangeDisposable, containerDisposable]);
 
@@ -207,14 +207,15 @@ export class SplitView implements IDisposable {
 		this.resize(index, delta, sizes);
 	}
 
-	private onViewChange(item: IViewItem): void {
+	private onViewChange(item: IViewItem, size: number | undefined): void {
 		const index = this.viewItems.indexOf(item);
 
 		if (index < 0 || index >= this.viewItems.length) {
 			return;
 		}
 
-		const size = clamp(item.size, item.view.minimumSize, item.view.maximumSize);
+		size = typeof size === 'number' ? size : item.size;
+		size = clamp(size, item.view.minimumSize, item.view.maximumSize);
 		item.size = size;
 		this.relayout();
 	}

src/vs/base/test/browser/ui/splitview/splitview.test.ts

@@ -10,7 +10,7 @@ import { Sash } from 'vs/base/browser/ui/sash/sash';
 
 class TestView implements IView {
 
-	private _onDidChange = new Emitter<void>();
+	private _onDidChange = new Emitter<number | undefined>();
 	readonly onDidChange = this._onDidChange.event;
 
 	get minimumSize(): number { return this._minimumSize; }