Adopt hover service in custom tree view

Part of #100741

src/vs/vscode.proposed.d.ts

@@ -3,6 +3,8 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import { MarkdownString } from 'vscode';
+
 /**
  * This is the place for API experiments and proposals.
  * These API are NOT stable and subject to change. They are only available in the Insiders
@@ -1154,6 +1156,11 @@ declare module 'vscode' {
 		 */
 		label?: string | TreeItemLabel | /* for compilation */ any;
 
+		/**
+		 * Content to be shown when you hover over the tree item.
+		 */
+		tooltip?: string | MarkdownString | /* for compilation */ any;
+
 		/**
 		 * Accessibility information used when screen reader interacts with this tree item.
 		 * Generally, a TreeItem has no need to set the `role` of the accessibilityInformation;

src/vs/workbench/api/browser/viewsExtensionPoint.ts

@@ -9,7 +9,7 @@ import { IJSONSchema } from 'vs/base/common/jsonSchema';
 import * as resources from 'vs/base/common/resources';
 import { ExtensionMessageCollector, ExtensionsRegistry, IExtensionPoint, IExtensionPointUser } from 'vs/workbench/services/extensions/common/extensionsRegistry';
 import { ViewContainer, IViewsRegistry, ITreeViewDescriptor, IViewContainersRegistry, Extensions as ViewContainerExtensions, TEST_VIEW_CONTAINER_ID, IViewDescriptor, ViewContainerLocation } from 'vs/workbench/common/views';
-import { TreeViewPane, CustomTreeView } from 'vs/workbench/browser/parts/views/treeView';
+import { TreeViewPane } from 'vs/workbench/browser/parts/views/treeView';
 import { ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
 import { coalesce, } from 'vs/base/common/arrays';
 import { IWorkbenchContributionsRegistry, Extensions as WorkbenchExtensions, IWorkbenchContribution } from 'vs/workbench/common/contributions';
@@ -31,6 +31,7 @@ import { SyncActionDescriptor } from 'vs/platform/actions/common/actions';
 import { ViewPaneContainer } from 'vs/workbench/browser/parts/views/viewPaneContainer';
 import { SyncDescriptor } from 'vs/platform/instantiation/common/descriptors';
 import { Codicon } from 'vs/base/common/codicons';
+import { CustomTreeView } from 'vs/workbench/contrib/views/browser/treeView';
 
 export interface IUserFriendlyViewsContainerDescriptor {
 	id: string;

src/vs/workbench/api/common/extHostTreeViews.ts

@@ -19,6 +19,8 @@ import { equals, coalesce } from 'vs/base/common/arrays';
 import { ILogService } from 'vs/platform/log/common/log';
 import { checkProposedApiEnabled } from 'vs/workbench/services/extensions/common/extensions';
 import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
+import { MarkdownString } from 'vs/workbench/api/common/extHostTypeConverters';
+import { IMarkdownString } from 'vs/base/common/htmlContent';
 
 type TreeItemHandle = string;
 
@@ -486,6 +488,17 @@ class ExtHostTreeView<T> extends Disposable {
 		return node;
 	}
 
+	private getTooltip(tooltip?: string | vscode.MarkdownString): string | IMarkdownString | undefined {
+		if (typeof tooltip === 'string') {
+			return tooltip;
+		} else if (tooltip === undefined) {
+			return undefined;
+		} else {
+			checkProposedApiEnabled(this.extension);
+			return MarkdownString.from(tooltip);
+		}
+	}
+
 	private createTreeNode(element: T, extensionTreeItem: vscode.TreeItem2, parent: TreeNode | Root): TreeNode {
 		const disposable = new DisposableStore();
 		const handle = this.createHandle(element, extensionTreeItem, parent);
@@ -496,7 +509,7 @@ class ExtHostTreeView<T> extends Disposable {
 			label: toTreeItemLabel(extensionTreeItem.label, this.extension),
 			description: extensionTreeItem.description,
 			resourceUri: extensionTreeItem.resourceUri,
-			tooltip: typeof extensionTreeItem.tooltip === 'string' ? extensionTreeItem.tooltip : undefined,
+			tooltip: this.getTooltip(extensionTreeItem.tooltip),
 			command: extensionTreeItem.command ? this.commands.toInternal(extensionTreeItem.command, disposable) : undefined,
 			contextValue: extensionTreeItem.contextValue,
 			icon,

src/vs/workbench/api/common/extHostTypes.ts

@@ -2101,7 +2101,7 @@ export class TreeItem {
 	iconPath?: string | URI | { light: string | URI; dark: string | URI; };
 	command?: vscode.Command;
 	contextValue?: string;
-	tooltip?: string;
+	tooltip?: string | vscode.MarkdownString;
 
 	constructor(label: string | vscode.TreeItemLabel, collapsibleState?: vscode.TreeItemCollapsibleState);
 	constructor(resourceUri: URI, collapsibleState?: vscode.TreeItemCollapsibleState);