2D Visualization笔记(X3) DynamicDataDisplay(wpf)(二)

Hello World Demo 分析
LineGraph的UpdateCore中有GetTransform和transform.DataToScreen(points). GetTransform是在父类PointsGraphBase中定义的

private DataTransform dataTransform = null;
public DataTransform DataTransform
{
	get { return dataTransform; }
	set
	{
		if (dataTransform != value)
		{
			dataTransform = value;
			Update();
		}
	}
}

protected CoordinateTransform GetTransform()
{
	if (Plotter == null)
		return null;

	var transform = Plotter2D.Viewport.Transform;
	if (dataTransform != null)
		transform = transform.WithDataTransform(dataTransform);

	return transform;
}

一个窗口中可以有多个Plot, 一个Plot就是一个视口(viewPort);CoordinateTransform有2个变换组成, 一个是数据变换(dataTransform), 先将数据变换到Plot(即视口viewPort), 另一个是视口变换, 将Plot变换到窗口的某一位置

	/// <summary>
	/// Base class for all data transforms.
	/// Defines methods to transform point from data coordinate system to viewport coordinates and vice versa.
	/// </summary>
	public abstract class DataTransform
	{
		/// <summary>
		/// Transforms the point in data coordinates to viewport coordinates.
		/// </summary>
		/// <param name="pt">The point in data coordinates.</param>
		/// <returns></returns>
		public abstract Point DataToViewport(Point pt);
		/// <summary>
		/// Transforms the point in viewport coordinates to data coordinates.
		/// </summary>
		/// <param name="pt">The point in viewport coordinates.</param>
		/// <returns></returns>
		public abstract Point ViewportToData(Point pt);

		private static readonly DataRect defaultDomain = DataRect.Empty;
		/// <summary>
		/// Gets the data domain.
		/// </summary>
		/// <value>The data domain.</value>
		public virtual DataRect DataDomain { get { return defaultDomain; } }
	}


namespace Microsoft.Research.DynamicDataDisplay
{
	/// <summary>
	/// A central class in 2d coordinate transformation in DynamicDataDisplay.
	/// Provides methods to transform point from one coordinate system to another.
	/// </summary>
	public sealed class CoordinateTransform
	{
		private CoordinateTransform(Rect visibleRect, Rect screenRect)
		{
			this.visibleRect = visibleRect;
			this.screenRect = screenRect;

			rxToScreen = screenRect.Width / visibleRect.Width;
			ryToScreen = screenRect.Height / visibleRect.Height;
			cxToScreen = visibleRect.Left * rxToScreen - screenRect.Left;
			cyToScreen = screenRect.Height + screenRect.Top + visibleRect.Top * ryToScreen;

			rxToData = visibleRect.Width / screenRect.Width;
			ryToData = visibleRect.Height / screenRect.Height;
			cxToData = screenRect.Left * rxToData - visibleRect.Left;
			cyToData = visibleRect.Height + visibleRect.Top + screenRect.Top * ryToData;
		}

		#region Coeffs
		double rxToScreen;
		double ryToScreen;
		double cxToScreen;
		double cyToScreen;

		double rxToData;
		double ryToData;
		double cxToData;
		double cyToData;
		#endregion

		#region Creation methods

		internal CoordinateTransform WithRects(Rect visibleRect, Rect screenRect)
		{
			CoordinateTransform copy = new CoordinateTransform(visibleRect, screenRect);
			copy.dataTransform = dataTransform;
			return copy;
		}

		/// <summary>
		/// Creates a new instance of CoordinateTransform with the given data transform.
		/// </summary>
		/// <param name="dataTransform">The data transform.</param>
		/// <returns></returns>
		public CoordinateTransform WithDataTransform(DataTransform dataTransform)
		{
			if (dataTransform == null)
				throw new ArgumentNullException("dataTransform");

			CoordinateTransform copy = new CoordinateTransform(visibleRect, screenRect);
			copy.dataTransform = dataTransform;
			return copy;
		}

		internal static CoordinateTransform CreateDefault()
		{
			CoordinateTransform transform = new CoordinateTransform(new Rect(0, 0, 1, 1), new Rect(0, 0, 1, 1));

			return transform;
		}

		#endregion

		#region Transform methods

		/// <summary>
		/// Transforms point from data coordinates to screen.
		/// </summary>
		/// <param name="dataPoint">The point in data coordinates.</param>
		/// <returns></returns>
		public Point DataToScreen(Point dataPoint)
		{
			Point viewportPoint = dataTransform.DataToViewport(dataPoint);

			Point screenPoint = new Point(viewportPoint.X * rxToScreen - cxToScreen,
				cyToScreen - viewportPoint.Y * ryToScreen);

			return screenPoint;
		}

		/// <summary>
		/// Transforms point from screen coordinates to data coordinates.
		/// </summary>
		/// <param name="screenPoint">The point in screen coordinates.</param>
		/// <returns></returns>
		public Point ScreenToData(Point screenPoint)
		{
			Point viewportPoint = new Point(screenPoint.X * rxToData - cxToData,
				cyToData - screenPoint.Y * ryToData);

			Point dataPoint = dataTransform.ViewportToData(viewportPoint);

			return dataPoint;
		}

		/// <summary>
		/// Transforms point from viewport coordinates to screen coordinates.
		/// </summary>
		/// <param name="viewportPoint">The point in viewport coordinates.</param>
		/// <returns></returns>
		public Point ViewportToScreen(Point viewportPoint)
		{
			Point screenPoint = new Point(viewportPoint.X * rxToScreen - cxToScreen,
				cyToScreen - viewportPoint.Y * ryToScreen);

			return screenPoint;
		}

		/// <summary>
		/// Transforms point from screen coordinates to viewport coordinates.
		/// </summary>
		/// <param name="screenPoint">The point in screen coordinates.</param>
		/// <returns></returns>
		public Point ScreenToViewport(Point screenPoint)
		{
			Point viewportPoint = new Point(screenPoint.X * rxToData - cxToData,
				cyToData - screenPoint.Y * ryToData);

			return viewportPoint;
		}

		#endregion

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private Rect visibleRect;
		/// <summary>
		/// Gets the viewport rectangle.
		/// </summary>
		/// <value>The viewport rect.</value>
		public Rect ViewportRect
		{
			get { return visibleRect; }
		}

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private Rect screenRect;
		/// <summary>
		/// Gets the screen rectangle.
		/// </summary>
		/// <value>The screen rect.</value>
		public Rect ScreenRect
		{
			get { return screenRect; }
		}

		[DebuggerBrowsable(DebuggerBrowsableState.Never)]
		private DataTransform dataTransform = DataTransforms.Identity;
		/// <summary>
		/// Gets the data transform.
		/// </summary>
		/// <value>The data transform.</value>
		public DataTransform DataTransform
		{
			get { return dataTransform; }
		}
	}
}

visibleRect是Plot所在的Rect, screenRect是窗口所在的Rect, 默认两个是重合的

internal static CoordinateTransform CreateDefault()
{
	CoordinateTransform transform = new CoordinateTransform(new Rect(0, 0, 1, 1), new Rect(0, 0, 1, 1));

	return transform;
}