Fix view model event and expose a way to get hidden areas (microsoft#156571)

* Fix emitting of wrong event in view model

* Add `IViewModel.getHiddenAreas`

Author: alexdima

src/vs/editor/common/viewModel.ts

@@ -48,6 +48,8 @@ export interface IViewModel extends ICursorSimpleModel {
 	getCompletelyVisibleViewRange(): Range;
 	getCompletelyVisibleViewRangeAtScrollTop(scrollTop: number): Range;
 
+	getHiddenAreas(): Range[];
+
 	getLineCount(): number;
 	getLineContent(lineNumber: number): string;
 	getLineLength(lineNumber: number): number;

src/vs/editor/common/viewModel/viewModelImpl.ts

@@ -36,7 +36,7 @@ import { ILineBreaksComputer, ILineBreaksComputerFactory, InjectedText } from 'v
 import { ViewEventHandler } from 'vs/editor/common/viewEventHandler';
 import { ICoordinatesConverter, InlineDecoration, IViewModel, IWhitespaceChangeAccessor, MinimapLinesRenderingData, OverviewRulerDecorationsGroup, ViewLineData, ViewLineRenderingData, ViewModelDecoration } from 'vs/editor/common/viewModel';
 import { ViewModelDecorations } from 'vs/editor/common/viewModel/viewModelDecorations';
-import { FocusChangedEvent, ModelContentChangedEvent, ModelDecorationsChangedEvent, ModelLanguageChangedEvent, ModelLanguageConfigurationChangedEvent, ModelOptionsChangedEvent, ModelTokensChangedEvent, OutgoingViewModelEvent, ReadOnlyEditAttemptEvent, ScrollChangedEvent, ViewModelEventDispatcher, ViewModelEventsCollector, ViewZonesChangedEvent } from 'vs/editor/common/viewModelEventDispatcher';
+import { FocusChangedEvent, HiddenAreasChangedEvent, ModelContentChangedEvent, ModelDecorationsChangedEvent, ModelLanguageChangedEvent, ModelLanguageConfigurationChangedEvent, ModelOptionsChangedEvent, ModelTokensChangedEvent, OutgoingViewModelEvent, ReadOnlyEditAttemptEvent, ScrollChangedEvent, ViewModelEventDispatcher, ViewModelEventsCollector, ViewZonesChangedEvent } from 'vs/editor/common/viewModelEventDispatcher';
 import { IViewModelLines, ViewModelLinesFromModelAsIs, ViewModelLinesFromProjectedModel } from 'vs/editor/common/viewModel/viewModelLines';
 import { IThemeService } from 'vs/platform/theme/common/themeService';
 
@@ -485,7 +485,7 @@ export class ViewModel extends Disposable implements IViewModel {
 		this._updateConfigurationViewLineCount.schedule();
 
 		if (lineMappingChanged) {
-			this._eventDispatcher.emitOutgoingEvent(new ViewZonesChangedEvent());
+			this._eventDispatcher.emitOutgoingEvent(new HiddenAreasChangedEvent());
 		}
 	}
 
@@ -508,6 +508,10 @@ export class ViewModel extends Disposable implements IViewModel {
 		return this._toModelVisibleRanges(visibleViewRange);
 	}
 
+	public getHiddenAreas(): Range[] {
+		return this._lines.getHiddenAreas();
+	}
+
 	private _toModelVisibleRanges(visibleViewRange: Range): Range[] {
 		const visibleRange = this.coordinatesConverter.convertViewRangeToModelRange(visibleViewRange);
 		const hiddenAreas = this._lines.getHiddenAreas();