Document: use a hash for Document#_selectedItems to speed up adding to and removing from it.

src/document/Document.js

@@ -37,7 +37,8 @@ var Document = this.Document = Base.extend({
 		this.symbols = [];
 		this.views = [new DocumentView(this)];
 		this.activeView = this.views[0];
-		this._selectedItems = [];
+		this._selectedItems = {};
+		this._selectedItemCount = 0;
 	},
 
 	getCurrentStyle: function() {
@@ -60,34 +61,50 @@ var Document = this.Document = Base.extend({
 	getSelectedItems: function() {
 		// TODO: return groups if their children are all selected,
 		// and filter out their children from the list.
-		return this._selectedItems;
+		var items = [];
+		Base.each(items, function(item) {
+			items.push(item);
+		});
+		return items;
 	},
-	
+
 	// TODO: implement setSelectedItems?
 	
+	_selectItem: function(item, select) {
+		if (select) {
+			this.selectedItemCount++;
+			this._selectedItems[item.getId()] = item;
+		} else {
+			this._selectedItemCount--;
+			delete this._selectedItems[item.getId()];
+		}
+	},
+	
 	draw: function() {
 		if (this.canvas) {
+			var context = this.context;
 			// Initial tests conclude that clearing the canvas using clearRect
 			// is always faster than setting canvas.width = canvas.width
 			// http://jsperf.com/clearrect-vs-setting-width/7
-			this.context.clearRect(0, 0,
+			context.clearRect(0, 0,
 					this.size.width + 1, this.size.height + 1);
-			this.context.save();
+			context.save();
 			var param = { offset: new Point(0, 0) };
 			for (var i = 0, l = this.layers.length; i < l; i++)
-				Item.draw(this.layers[i], this.context, param);
-			this.context.restore();
+				Item.draw(this.layers[i], context, param);
+			context.restore();
 
 			// Draw the selection of the selected items in the document:
-			var selectedItems = this._selectedItems,
-				length = selectedItems.length;
-			if (length) {
-				this.context.strokeWidth = 1;
+			if (this._selectedItemCount > 0) {
+				context.save();
+				context.strokeWidth = 1;
 				// Todo: use Layer#color
-				this.context.strokeStyle = this.context.fillStyle = '#4f7aff';
+				context.strokeStyle = context.fillStyle = '#4f7aff';
 				param = { selection: true };
-				for (var i = 0; i < length; i++)
-					selectedItems[i].draw(this.context, param);
+				Base.each(this.selectedItems, function(item) {
+					item.draw(context, param);
+				});
+				context.restore();
 			}
 		}
 	},

src/item/Item.js

@@ -64,15 +64,7 @@ var Item = this.Item = Base.extend({
 				// TODO: when an item is removed or moved to another
 				// document, it needs to be removed from _selectedItems
 				this._selected = selected;
-				var selectedItems = this._document._selectedItems;
-				if (selected) {
-					selectedItems.push(this);
-				} else {
-					// TODO: is there a faster way?
-					var index = selectedItems.indexOf(this);
-					if (index != -1)
-						selectedItems.splice(index, 1);
-				}
+				this._document._selectItem(this, selected);
 			}
 		}
 	},

src/path/Path.js

@@ -136,17 +136,8 @@ var Path = this.Path = PathItem.extend({
 	setSelected: function(selected) {
 		var wasSelected = this.isSelected();
 		var length = this._segments.length;
-		if (!wasSelected != !selected && length) {
-			var selectedItems = this._document._selectedItems;
-			if (selected) {
-				selectedItems.push(this);
-			} else {
-				// TODO: is there a faster way?
-				var index = selectedItems.indexOf(this);
-				if (index != -1)
-					selectedItems.splice(index, 1);
-			}
-		}
+		if (!wasSelected != !selected && length)
+			this._document._selectItem(this, selected);
 		this._selectedSegmentCount = selected ? length : 0;
 		for (var i = 0; i < length; i++)
 			this._segments[i]._selectionState = selected

src/path/Segment.js

@@ -221,15 +221,12 @@ var Segment = this.Segment = Base.extend({
 				selectedItems = path._document._selectedItems;
 			if (!this._selectionState) {
 				path._selectedSegmentCount--;
-				if (path._selectedSegmentCount == 0) {
-					var index = selectedItems.indexOf(this);
-					selectedItems.slice(index, 1);
-				}
+				if (path._selectedSegmentCount == 0)
+					path._document._selectItem(path, true);
 			} else {
 				path._selectedSegmentCount++;
-				if (path._selectedSegmentCount == 1) {
-					selectedItems.push(path);
-				}
+				if (path._selectedSegmentCount == 1)
+					path._document._selectItem(path, false);
 			}
 		}	
 	},