Fixes Microsoft/monaco-editor#806: Emit focus/blur events only when the state changes

src/vs/editor/browser/widget/codeEditorWidget.ts

@@ -101,13 +101,7 @@ export abstract class CodeEditorWidget extends CommonCodeEditor implements edito
 
 		this._focusTracker = new CodeEditorWidgetFocusTracker(domElement);
 		this._focusTracker.onChange(() => {
-			let hasFocus = this._focusTracker.hasFocus();
-
-			if (hasFocus) {
-				this._onDidFocusEditor.fire();
-			} else {
-				this._onDidBlurEditor.fire();
-			}
+			this._editorFocus.setValue(this._focusTracker.hasFocus());
 		});
 
 		this.contentWidgets = {};
@@ -431,13 +425,13 @@ export abstract class CodeEditorWidget extends CommonCodeEditor implements edito
 		const viewEventBus = this._view.getInternalEventBus();
 
 		viewEventBus.onDidGainFocus = () => {
-			this._onDidFocusEditorText.fire();
+			this._editorTextFocus.setValue(true);
 			// In IE, the focus is not synchronous, so we give it a little help
-			this._onDidFocusEditor.fire();
+			this._editorFocus.setValue(true);
 		};
 
 		viewEventBus.onDidScroll = (e) => this._onDidScrollChange.fire(e);
-		viewEventBus.onDidLoseFocus = () => this._onDidBlurEditorText.fire();
+		viewEventBus.onDidLoseFocus = () => this._editorTextFocus.setValue(false);
 		viewEventBus.onContextMenu = (e) => this._onContextMenu.fire(e);
 		viewEventBus.onMouseDown = (e) => this._onMouseDown.fire(e);
 		viewEventBus.onMouseUp = (e) => this._onMouseUp.fire(e);

src/vs/editor/common/commonCodeEditor.ts

@@ -68,17 +68,13 @@ export abstract class CommonCodeEditor extends Disposable {
 	private readonly _onDidLayoutChange: Emitter<editorOptions.EditorLayoutInfo> = this._register(new Emitter<editorOptions.EditorLayoutInfo>());
 	public readonly onDidLayoutChange: Event<editorOptions.EditorLayoutInfo> = this._onDidLayoutChange.event;
 
-	protected readonly _onDidFocusEditorText: Emitter<void> = this._register(new Emitter<void>());
-	public readonly onDidFocusEditorText: Event<void> = this._onDidFocusEditorText.event;
+	protected _editorTextFocus: BooleanEventEmitter = this._register(new BooleanEventEmitter());
+	public readonly onDidFocusEditorText: Event<void> = this._editorTextFocus.onDidChangeToTrue;
+	public readonly onDidBlurEditorText: Event<void> = this._editorTextFocus.onDidChangeToFalse;
 
-	protected readonly _onDidBlurEditorText: Emitter<void> = this._register(new Emitter<void>());
-	public readonly onDidBlurEditorText: Event<void> = this._onDidBlurEditorText.event;
-
-	protected readonly _onDidFocusEditor: Emitter<void> = this._register(new Emitter<void>());
-	public readonly onDidFocusEditor: Event<void> = this._onDidFocusEditor.event;
-
-	protected readonly _onDidBlurEditor: Emitter<void> = this._register(new Emitter<void>());
-	public readonly onDidBlurEditor: Event<void> = this._onDidBlurEditor.event;
+	protected _editorFocus: BooleanEventEmitter = this._register(new BooleanEventEmitter());
+	public readonly onDidFocusEditor: Event<void> = this._editorFocus.onDidChangeToTrue;
+	public readonly onDidBlurEditor: Event<void> = this._editorFocus.onDidChangeToFalse;
 
 	private readonly _onWillType: Emitter<string> = this._register(new Emitter<string>());
 	public readonly onWillType = this._onWillType.event;
@@ -1047,6 +1043,40 @@ export abstract class CommonCodeEditor extends Disposable {
 	}
 }
 
+const enum BooleanEventValue {
+	NotSet,
+	False,
+	True
+}
+
+export class BooleanEventEmitter extends Disposable {
+	private readonly _onDidChangeToTrue: Emitter<void> = this._register(new Emitter<void>());
+	public readonly onDidChangeToTrue: Event<void> = this._onDidChangeToTrue.event;
+
+	private readonly _onDidChangeToFalse: Emitter<void> = this._register(new Emitter<void>());
+	public readonly onDidChangeToFalse: Event<void> = this._onDidChangeToFalse.event;
+
+	private _value: BooleanEventValue;
+
+	constructor() {
+		super();
+		this._value = BooleanEventValue.NotSet;
+	}
+
+	public setValue(_value: boolean) {
+		let value = (_value ? BooleanEventValue.True : BooleanEventValue.False);
+		if (this._value === value) {
+			return;
+		}
+		this._value = value;
+		if (this._value === BooleanEventValue.True) {
+			this._onDidChangeToTrue.fire();
+		} else if (this._value === BooleanEventValue.False) {
+			this._onDidChangeToFalse.fire();
+		}
+	}
+}
+
 class EditorContextKeysManager extends Disposable {
 
 	private _editor: CommonCodeEditor;