Initial Commit

ViewportRestrictions/DataHeightRestriction.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+
+namespace Microsoft.Research.DynamicDataDisplay.ViewportRestrictions
+{
+	public class DataHeightRestriction : ViewportRestriction, ISupportAttachToViewport
+	{
+		private double yEnlargeCoeff = 1.1;
+		public double YEnlargeCoeff
+		{
+			get { return yEnlargeCoeff; }
+			set
+			{
+				if (yEnlargeCoeff != value)
+				{
+					yEnlargeCoeff = value;
+					RaiseChanged();
+				}
+			}
+		}
+
+		public override DataRect Apply(DataRect oldDataRect, DataRect newDataRect, Viewport2D viewport)
+		{
+			DataRect overallBounds = DataRect.Empty;
+
+			foreach (var chart in viewport.ContentBoundsHosts)
+			{
+                var plotterElement = chart as IPlotterElement;
+				var visual = viewport.Plotter.VisualBindings[plotterElement];
+				var points = (ReadOnlyCollection<Point>)PointsGraphBase.GetVisiblePoints(visual);
+				if (points != null)
+				{
+
+					// searching for indices of chart's visible points which are near left and right borders of newDataRect
+					double startX = newDataRect.XMin;
+					double endX = newDataRect.XMax;
+
+					if (points[0].X > endX || points[points.Count - 1].X < startX)
+					{
+						continue;
+					}
+
+					int startIndex = -1;
+
+					// we assume that points are sorted by x values ascending
+					if (startX <= points[0].X)
+					{
+						startIndex = 0;
+					}
+					else
+					{
+						for (int i = 1; i < points.Count - 1; i++)
+						{
+							if (points[i].X <= startX && startX < points[i + 1].X)
+							{
+								startIndex = i;
+								break;
+							}
+						}
+					}
+
+					int endIndex = points.Count;
+
+					if (points[points.Count - 1].X < endX)
+					{
+						endIndex = points.Count;
+					}
+					else
+					{
+						for (int i = points.Count - 1; i >= 1; i--)
+						{
+							if (points[i - 1].X <= endX && endX < points[i].X)
+							{
+								endIndex = i;
+								break;
+							}
+						}
+					}
+
+					Rect bounds = Rect.Empty;
+					for (int i = startIndex; i < endIndex; i++)
+					{
+						bounds.Union(points[i]);
+					}
+					if (startIndex > 0)
+					{
+						Point pt = GetInterpolatedPoint(startX, points[startIndex], points[startIndex - 1]);
+						bounds.Union(pt);
+					}
+					if (endIndex < points.Count - 1)
+					{
+						Point pt = GetInterpolatedPoint(endX, points[endIndex], points[endIndex + 1]);
+						bounds.Union(pt);
+					}
+
+					overallBounds.Union(bounds);
+				}
+			}
+
+			if (!overallBounds.IsEmpty)
+			{
+				double y = overallBounds.YMin;
+				double height = overallBounds.Height;
+
+				if (height == 0)
+				{
+					height = newDataRect.Height;
+					y -= height / 2;
+				}
+
+				newDataRect = new DataRect(newDataRect.XMin, y, newDataRect.Width, height);
+				newDataRect = DataRectExtensions.ZoomY(newDataRect, newDataRect.GetCenter(), yEnlargeCoeff);
+			}
+
+			return newDataRect;
+		}
+
+		private static Point GetInterpolatedPoint(double x, Point p1, Point p2)
+		{
+			double xRatio = (x - p1.X) / (p2.X - p1.X);
+			double y = (1 - xRatio) * p1.Y + xRatio * p2.Y;
+
+			return new Point(x, y);
+		}
+
+		#region ISupportAttach Members
+
+		void ISupportAttachToViewport.Attach(Viewport2D viewport)
+		{
+			((INotifyCollectionChanged)viewport.ContentBoundsHosts).CollectionChanged += OnContentBoundsHostsChanged;
+
+			foreach (var item in viewport.ContentBoundsHosts)
+			{
+				PointsGraphBase chart = item as PointsGraphBase;
+				if (chart != null)
+				{
+					chart.ProvideVisiblePoints = true;
+				}
+			}
+		}
+
+		private void OnContentBoundsHostsChanged(object sender, NotifyCollectionChangedEventArgs e)
+		{
+			if (e.NewItems != null)
+			{
+				foreach (var item in e.NewItems)
+				{
+					PointsGraphBase chart = item as PointsGraphBase;
+					if (chart != null)
+					{
+						chart.ProvideVisiblePoints = true;
+					}
+				}
+			}
+
+			// todo probably set ProvideVisiblePoints to false on OldItems
+		}
+
+		void ISupportAttachToViewport.Detach(Viewport2D viewport)
+		{
+			((INotifyCollectionChanged)viewport.ContentBoundsHosts).CollectionChanged -= OnContentBoundsHostsChanged;
+		}
+
+		#endregion
+	}
+}