Snapline for middle of Object (like in VisualStudio)

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/Extensions/SnaplinePlacementBehavior.cs

@@ -41,51 +41,51 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 		List<Snapline> horizontalMap;
 		List<Snapline> verticalMap;
 		double? baseline;
-
+		
 		public const double Accuracy = 5;
 		public const double Margin = 8;
-
+		
 		public override void BeginPlacement(PlacementOperation operation)
 		{
 			base.BeginPlacement(operation);
 			CreateSurface(operation);
 		}
-
+		
 		public override void EndPlacement(PlacementOperation operation)
 		{
 			base.EndPlacement(operation);
 			DeleteSurface();
 		}
-
+		
 		public override void EnterContainer(PlacementOperation operation)
 		{
 			base.EnterContainer(operation);
 			CreateSurface(operation);
 		}
-
+		
 		public override void LeaveContainer(PlacementOperation operation)
 		{
 			base.LeaveContainer(operation);
 			DeleteSurface();
 		}
-
+		
 		public override void BeforeSetPosition(PlacementOperation operation)
 		{
 			base.BeforeSetPosition(operation);
 			if (surface == null) return;
-
+			
 			DesignPanel designPanel = ExtendedItem.Services.DesignPanel as DesignPanel;
 			if (designPanel == null || !designPanel.UseSnaplinePlacement)
 				return;
 			
 			surface.Children.Clear();
 			if (Keyboard.IsKeyDown(Key.LeftCtrl)) return;
-
+			
 			Rect bounds = Rect.Empty;
 			foreach (var item in operation.PlacedItems) {
 				bounds.Union(item.Bounds);
 			}
-
+			
 			var horizontalInput = new List<Snapline>();
 			var verticalInput = new List<Snapline>();
 			var info = operation.PlacedItems[0];
@@ -99,7 +99,7 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 					horizontalInput.Add(new Snapline() { Group = 1, Offset = textOffset, Start = bounds.Left, End = bounds.Right });
 				}
 			}
-
+			
 			// debug
 			//foreach (var t in horizontalMap.Concat(horizontalInput)) {
 			//    surface.Children.Add(new Line() { X1 = t.Start, X2 = t.End, Y1 = t.Offset, Y2 = t.Offset, Stroke = Brushes.Black });
@@ -108,12 +108,12 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			//    surface.Children.Add(new Line() { X1 = t.Offset, X2 = t.Offset, Y1 = t.Start , Y2 = t.End, Stroke = Brushes.Black });
 			//}
 			//return;
-
+			
 			List<Snapline> drawLines;
 			double delta;
-
+			
 			if (Snap(horizontalInput, horizontalMap, Accuracy, out drawLines, out delta)) {
-
+				
 				if (operation.Type == PlacementType.Resize) {
 					if (info.ResizeThumbAlignment.Vertical == VerticalAlignment.Top) {
 						bounds.Y += delta;
@@ -129,14 +129,14 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 						item.Bounds = r;
 					}
 				}
-
+				
 				foreach (var d in drawLines) {
 					DrawLine(d.Start, d.Offset, d.End, d.Offset);
 				}
 			}
-
+			
 			if (Snap(verticalInput, verticalMap, Accuracy, out drawLines, out delta)) {
-
+				
 				if (operation.Type == PlacementType.Resize) {
 					if (info.ResizeThumbAlignment.Horizontal == HorizontalAlignment.Left) {
 						bounds.X += delta;
@@ -158,52 +158,52 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 				}
 			}
 		}
-
+		
 		void CreateSurface(PlacementOperation operation)
 		{
 			if (ExtendedItem.Services.GetService<IDesignPanel>() != null) {
-
+				
 				surface = new Canvas();
 				adornerPanel = new AdornerPanel();
 				adornerPanel.SetAdornedElement(ExtendedItem.View, ExtendedItem);
 				AdornerPanel.SetPlacement(surface, AdornerPlacement.FillContent);
 				adornerPanel.Children.Add(surface);
 				ExtendedItem.Services.DesignPanel.Adorners.Add(adornerPanel);
-
+				
 				BuildMaps(operation);
-
+				
 				if (operation.Type != PlacementType.Resize && operation.PlacedItems.Count == 1) {
 					baseline = GetBaseline(operation.PlacedItems[0].Item.View);
 				}
 			}
 		}
-
+		
 		void BuildMaps(PlacementOperation operation)
 		{
 			horizontalMap = new List<Snapline>();
 			verticalMap = new List<Snapline>();
-
+			
 			var containerRect = new Rect(0, 0, ModelTools.GetWidth(ExtendedItem.View), ModelTools.GetHeight(ExtendedItem.View));
 			AddLines(containerRect, -Margin, false);
-
+			
 			AddLines(containerRect, 0, false);
 			
 			foreach (var item in ExtendedItem.ContentProperty.CollectionElements
-			         .Except(operation.PlacedItems.Select(f => f.Item)))
+				.Except(operation.PlacedItems.Select(f => f.Item)))
 			{
 				var bounds = GetPosition(operation, item);
-
+				
 				AddLines(bounds, 0, false);
 				AddLines(bounds, Margin, true);
 				AddBaseline(item, bounds, horizontalMap);
 			}
 		}
-
+		
 		void AddLines(Rect r, double inflate, bool requireOverlap)
 		{
 			AddLines(r, inflate, requireOverlap, horizontalMap, verticalMap, null);
 		}
-
+		
 		void AddLines(Rect r, double inflate, bool requireOverlap, List<Snapline> h, List<Snapline> v, PlacementAlignment? filter)
 		{
 			Rect r2 = r;
@@ -217,8 +217,14 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 				v.Add(new Snapline() { RequireOverlap = requireOverlap, Offset = r2.Left - 1, Start = r.Top, End = r.Bottom });
 			if (filter == null || filter.Value.Horizontal == HorizontalAlignment.Right)
 				v.Add(new Snapline() { RequireOverlap = requireOverlap, Offset = r2.Right - 1, Start = r.Top, End = r.Bottom });
+			
+			if (filter == null)
+			{
+				h.Add(new Snapline() { RequireOverlap = requireOverlap, Offset = r2.Top + Math.Abs((r2.Top - r2.Bottom) / 2), Start = r.Left, End = r.Right });
+				v.Add(new Snapline() { RequireOverlap = requireOverlap, Offset = r2.Left + Math.Abs((r2.Left - r2.Right) / 2), Start = r.Top, End = r.Bottom });
+			}
 		}
-
+		
 		void AddBaseline(DesignItem item, Rect bounds, List<Snapline> list)
 		{
 			var baseline = GetBaseline(item.View);
@@ -227,7 +233,7 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 				list.Add(new Snapline() { Group = 1, Offset = textOffset, Start = bounds.Left, End = bounds.Right });
 			}
 		}
-
+		
 		void DeleteSurface()
 		{
 			if (surface != null) {
@@ -238,7 +244,7 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 				verticalMap = null;
 			}
 		}
-
+		
 		void DrawLine(double x1, double y1, double x2, double y2)
 		{
 			var line1 = new Line() {
@@ -250,7 +256,7 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 				Stroke = Brushes.White
 			};
 			surface.Children.Add(line1);
-
+			
 			var line2 = new Line() {
 				X1 = x1,
 				Y1 = y1,
@@ -263,7 +269,7 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			};
 			surface.Children.Add(line2);
 		}
-
+		
 		//TODO: GlyphRun must be used
 		static double? GetBaseline(UIElement element) {
 			var textBox = element as TextBox;
@@ -274,21 +280,21 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			var textBlock = element as TextBlock;
 			if (textBlock != null)
 				return textBlock.TranslatePoint(new Point(0, textBlock.ActualHeight), element).Y;
-
+			
 			return null;
 		}
-
+		
 		static bool Snap(List<Snapline> input, List<Snapline> map, double accuracy,
-		                 out List<Snapline> drawLines, out double delta)
+			out List<Snapline> drawLines, out double delta)
 		{
 			delta = double.MaxValue;
 			drawLines = null;
-
+			
 			foreach (var inputLine in input) {
 				foreach (var mapLine in map) {
 					if (Math.Abs(mapLine.Offset - inputLine.Offset) <= accuracy) {
 						if (!inputLine.RequireOverlap && !mapLine.RequireOverlap ||
-						    Math.Max(inputLine.Start, mapLine.Start) < Math.Min(inputLine.End, mapLine.End))
+							Math.Max(inputLine.Start, mapLine.Start) < Math.Min(inputLine.End, mapLine.End))
 						{
 							if (mapLine.Group == inputLine.Group)
 								delta = mapLine.Offset - inputLine.Offset;
@@ -296,10 +302,10 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 					}
 				}
 			}
-
+			
 			if (delta == double.MaxValue) return false;
 			var offsetDict = new Dictionary<double, Snapline>();
-
+			
 			foreach (var inputLine in input) {
 				inputLine.Offset += delta;
 				foreach (var mapLine in map) {
@@ -318,11 +324,11 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 					}
 				}
 			}
-
+			
 			drawLines = offsetDict.Values.ToList();
 			return true;
 		}
-
+		
 		[DebuggerDisplay("Snapline: {Offset}")]
 		class Snapline
 		{