add eventing and update command

virtual-document-sample/README.md

@@ -2,7 +2,7 @@
 
 This is a sample extension that shows how to add virtual documents to the editor.
 
-![cowsay](https://github.com/Microsoft/vscode-extension-samples/blob/master/virtual-document-sample/preview.png)
+![cowsay](https://github.com/Microsoft/vscode-extension-samples/blob/master/virtual-document-sample/cowsay.gif)
 
 
 ## VS Code API

virtual-document-sample/package.json

@@ -22,9 +22,30 @@
 	],
 	"main": "./out/extension",
 	"contributes": {
-		"commands": {
-			"command": "cowsay.say",
-			"title": "cowsay"
+		"commands": [
+			{
+				"command": "cowsay.say",
+				"title": "cowsay"
+			},
+			{
+				"command": "cowsay.backwards",
+				"title": "cowsay (↹)"
+			}
+		],
+		"menus": {
+			"editor/title": [
+				{
+					"command": "cowsay.backwards",
+					"group": "navigation",
+					"when": "resourceScheme == cowsay"
+				}
+			],
+			"commandPalette": [
+				{
+					"command": "cowsay.backwards",
+					"when": "resourceScheme == cowsay"
+				}
+			]
 		}
 	},
 	"scripts": {

virtual-document-sample/src/extension.ts

@@ -12,6 +12,11 @@ export function activate({ subscriptions }: vscode.ExtensionContext) {
 	// register a content provider for the cowsay-scheme
 	const myScheme = 'cowsay';
 	const myProvider = new class implements vscode.TextDocumentContentProvider {
+
+		// emitter and its event
+		onDidChangeEmitter = new vscode.EventEmitter<vscode.Uri>();
+		onDidChange = this.onDidChangeEmitter.event;
+
 		provideTextDocumentContent(uri: vscode.Uri): string {
 			// simply invoke cowsay, use uri-path as text
 			return cowsay.say({ text: uri.path });
@@ -24,8 +29,24 @@ export function activate({ subscriptions }: vscode.ExtensionContext) {
 		let what = await vscode.window.showInputBox({ placeHolder: 'cowsay...' });
 		if (what) {
 			let uri = vscode.Uri.parse('cowsay:' + what);
-			let doc = await vscode.workspace.openTextDocument(uri);
+			let doc = await vscode.workspace.openTextDocument(uri); // calls back into the provider
 			await vscode.window.showTextDocument(doc, { preview: false });
 		}
 	}));
+
+	// register a command that updates the current cowsay
+	subscriptions.push(vscode.commands.registerCommand('cowsay.backwards', async () => {
+		if (!vscode.window.activeTextEditor) {
+			return; // no editor
+		}
+		let { document } = vscode.window.activeTextEditor;
+		if (document.uri.scheme !== myScheme) {
+			return; // not my scheme
+		}
+		// get path-components, reverse it, and create a new uri
+		let say = document.uri.path;
+		let newSay = say.split('').reverse().join('');
+		let newUri = document.uri.with({ path: newSay });
+		await vscode.window.showTextDocument(newUri, { preview: false });
+	}))
 }