allow viewZones to be shown before first visible line (when hidden ranges are in effect) (microsoft#185201)

fyi @alexdima

Author: jrieken

src/vs/editor/browser/viewParts/viewZones/viewZones.ts

@@ -181,7 +181,7 @@ export class ViewZones extends ViewPart {
 			});
 		}
 
-		const viewPosition = this._context.viewModel.coordinatesConverter.convertModelPositionToViewPosition(zoneAfterModelPosition, zone.afterColumnAffinity);
+		const viewPosition = this._context.viewModel.coordinatesConverter.convertModelPositionToViewPosition(zoneAfterModelPosition, zone.afterColumnAffinity, true);
 		const isVisible = zone.showInHiddenAreas || this._context.viewModel.coordinatesConverter.modelPositionIsVisible(zoneBeforeModelPosition);
 		return {
 			isInHiddenArea: !isVisible,

src/vs/editor/common/viewModel.ts

@@ -210,7 +210,7 @@ export interface ICoordinatesConverter {
 	validateViewRange(viewRange: Range, expectedModelRange: Range): Range;
 
 	// Model -> View conversion and related methods
-	convertModelPositionToViewPosition(modelPosition: Position, affinity?: PositionAffinity): Position;
+	convertModelPositionToViewPosition(modelPosition: Position, affinity?: PositionAffinity, allowZeroLineNumber?: boolean): Position;
 	/**
 	 * @param affinity Only has an effect if the range is empty.
 	*/

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

@@ -830,7 +830,7 @@ export class ViewModelLinesFromProjectedModel implements IViewModelLines {
 		return new Range(start.lineNumber, start.column, end.lineNumber, end.column);
 	}
 
-	public convertModelPositionToViewPosition(_modelLineNumber: number, _modelColumn: number, affinity: PositionAffinity = PositionAffinity.None): Position {
+	public convertModelPositionToViewPosition(_modelLineNumber: number, _modelColumn: number, affinity: PositionAffinity = PositionAffinity.None, allowZeroLineNumber: boolean = false): Position {
 
 		const validPosition = this.model.validatePosition(new Position(_modelLineNumber, _modelColumn));
 		const inputLineNumber = validPosition.lineNumber;
@@ -844,7 +844,8 @@ export class ViewModelLinesFromProjectedModel implements IViewModelLines {
 		if (lineIndex === 0 && !this.modelLineProjections[lineIndex].isVisible()) {
 			// Could not reach a real line
 			// console.log('in -> out ' + inputLineNumber + ',' + inputColumn + ' ===> ' + 1 + ',' + 1);
-			return new Position(1, 1);
+			// TODO@alexdima@hediet this isn't soo pretty
+			return new Position(allowZeroLineNumber ? 0 : 1, 1);
 		}
 		const deltaLineNumber = 1 + this.projectedModelLineLineCounts.getPrefixSum(lineIndex);
 
@@ -1070,8 +1071,8 @@ class CoordinatesConverter implements ICoordinatesConverter {
 
 	// Model -> View conversion and related methods
 
-	public convertModelPositionToViewPosition(modelPosition: Position, affinity?: PositionAffinity): Position {
-		return this._lines.convertModelPositionToViewPosition(modelPosition.lineNumber, modelPosition.column, affinity);
+	public convertModelPositionToViewPosition(modelPosition: Position, affinity?: PositionAffinity, allowZero?: boolean): Position {
+		return this._lines.convertModelPositionToViewPosition(modelPosition.lineNumber, modelPosition.column, affinity, allowZero);
 	}
 
 	public convertModelRangeToViewRange(modelRange: Range, affinity?: PositionAffinity): Range {