autofilter: try to show same row range after filter application

problem:
when autofilter is applied sheet reset to view the first row(i.e row 0)
very inconvenient with big sheets to go and find the row you were looking at

now after this patch
when autofilter is applied we try to show row which is in current view and will
also be visible after applying the filter. In case if no row will be visible after
filter from current view we show the next visible row

example 1:
our current view is showing row 550 to 580
after autofilter row 570 is first visible row in this range
so the view will reset to row 570 as first row in the view

example 1:
our current view is showing row 550 to 580
after autofilter no row is visible in this range
row 603 is first visible row afte this range
so the view will reset to row 603 as first row in the view

Signed-off-by: Pranam Lashkari <lpranam@collabora.com>
Change-Id: I02a7315e7a42ef1f0a6f5dc4ab4be05b8aa6f5a8

Author: lpranam

browser/src/layer/tile/CalcTileLayer.js

@@ -802,8 +802,17 @@ window.L.CalcTileLayer = window.L.CanvasTileLayer.extend({
 
 		this._replayPrintTwipsMsgs(differentSheet);
 
-		this.sheetGeometry.setViewArea(this._pixelsToTwips(this._map._getTopLeftPoint()),
-			this._pixelsToTwips(this._map.getSize()));
+		if (this.sheetGeometry.autoFilterChanged) {
+			this.sheetGeometry.autoFilterChanged = false;
+			let firstVisibleRow = this.sheetGeometry.getFirstNewVisibleRow();
+			app.activeDocument.activeLayout.scrollTo(
+				this._map._getTopLeftPoint().x,
+				this.sheetGeometry.getRowsGeometry().getElementData(firstVisibleRow).startpos);
+		} else {
+			this.sheetGeometry.setViewArea(
+				this._pixelsToTwips(this._map._getTopLeftPoint()),
+				this._pixelsToTwips(this._map.getSize()));
+		}
 
 		this._addRemoveGroupSections();
 
@@ -931,6 +940,10 @@ window.L.CalcTileLayer = window.L.CanvasTileLayer.extend({
 		else if (e.commandName === 'AutoFilterInfo') {
 			app.calc.autoFilterCell = { 'row': e.state.row, 'column': e.state.column };
 		}
+		else if (e.commandName === 'AutoFilterChange')
+		{
+			this.sheetGeometry.autoFilterChanged = true;
+		}
 		else if (e.commandName === 'PivotTableFilterInfo') {
 			app.calc.pivotTableFilterCell = { 'row': e.state.row, 'column': e.state.column };
 		}

browser/src/layer/tile/SheetGeometry.ts

@@ -209,6 +209,51 @@ export class SheetGeometry {
 		return true;
 	}
 
+	/**
+	 * Find which will be new first visible row after updating the sheet geometry
+	 */
+	public getFirstNewVisibleRow(): number {
+		// Find first the visible rows in current view (before new sheet geometry is applied)
+		const target: number = this.getViewRowRange().start;
+		const invisibleRows: BoolSpanList = this.getRowsGeometry().getInvisibleSpanList(); //(hidden rows list in new geometry)
+
+		if (target === 0)
+			return 0;
+
+		let start: number = 0;
+		let end: number = invisibleRows._spanlist.length - 1;
+		let ans: number = -1;
+
+		// Just one span means every row is visible
+		if (start === 0 && end === 0)
+			return target;
+
+		// Modified binary search to find next visible of after the target row
+		while (start <= end) {
+			const mid = Math.floor((start + end) / 2);
+			if (invisibleRows._spanlist[mid] <= target) {
+				start = mid + 1;
+			} else {
+				ans = mid;
+				end = mid - 1;
+			}
+		}
+
+		// InvisibleRows is list of ranges in form of
+		// Like: 5 8 10 20... -> Means that visible up  to 5 (including), hidden up to 8 (including), visible up to 10 (including), hidden up to 20 (including)...
+		if (ans !== -1) {
+			if (ans === 0)
+				return 0;
+			// If its hidden index then +1 will be visible
+			if (ans % 2 === 0 && (ans + 1 < invisibleRows._spanlist.length)) {
+				return invisibleRows._spanlist[ans + 1];
+			} else {
+				return invisibleRows._spanlist[ans];
+			}
+		}
+		return 0;
+	}
+
 	public getPart(): number {
 		return this._part;
 	}
@@ -507,6 +552,7 @@ export class SheetDimension {
 	private _filtered: BoolSpanList;
 	private _outlines: DimensionOutlines;
 	private _visibleSizes: SpanList;
+	private _invisibleSpanList: BoolSpanList;
 
 	private _maxIndex: number;
 	private _tileSizeTwips: number;
@@ -531,6 +577,8 @@ export class SheetDimension {
 		this._visibleSizes = undefined;
 	}
 
+	public getInvisibleSpanList(): BoolSpanList { return this._invisibleSpanList; }
+
 	public update(jsonObject: SheetDimensionCoreData): boolean {
 
 		if (typeof jsonObject !== 'object') {
@@ -595,8 +643,8 @@ export class SheetDimension {
 
 	private _updateVisible() {
 
-		var invisibleSpanList = this._hidden.union(this._filtered); // this._hidden is not modified.
-		this._visibleSizes = this._sizes.applyZeroValues(invisibleSpanList); // this._sizes is not modified.
+		this._invisibleSpanList = this._hidden.union(this._filtered); // this._hidden is not modified.
+		this._visibleSizes = this._sizes.applyZeroValues(this._invisibleSpanList); // this._sizes is not modified.
 		this._updatePositions();
 	}