Question

I’m working with an open source charting library that creates markers on a graph. (Dynamic Data Display) The markers that I’m creating are created with Rect objects. I noticed that all the Shapes in System.Windows.Shapes have a ToolTip property, but System.Windows.Rect does not. I want to have a tooltip pop up telling the user the price value of the marker when the mouse hovers over it.
I was thinking about creating and popping up a tooltip when the mouse enters the area that the rect occupies, but I don’t know how possible that is considering the rect will be zoomed/panned around by the chart. Any other suggestions?

Here is my code for the marker I am creating (From Felice Pollano Blog)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Shapes;
using System.Windows.Controls;
using System.Text;
using System.Windows;
using System.Windows.Media;

namespace Microsoft.Research.DynamicDataDisplay.PointMarkers
{
public class CandleStickPointMarker:ShapePointMarker,ITransformAware
{
    public double CandlestickWidth
    {
        get { return (double)GetValue(CandlestickWidthProperty); }
        set { SetValue(CandlestickWidthProperty, value); }
    }
    public static readonly DependencyProperty CandlestickWidthProperty =
        DependencyProperty.Register("CandlestickWidth", typeof(double), typeof(CandleStickPointMarker), new UIPropertyMetadata(4.0));
    public double CandlestickStrokeWidth
    {
        get { return (double)GetValue(CandlestickStrokeWidthProperty); }
        set { SetValue(CandlestickStrokeWidthProperty, value); }
    }

    public static readonly DependencyProperty CandlestickStrokeWidthProperty =
        DependencyProperty.Register("CandlestickStrokeWidth", typeof(double), typeof(CandleStickPointMarker), new UIPropertyMetadata(1.0));
    public Brush WhiteCandleFill
    {
        get { return (Brush)GetValue(WhiteCandleFillProperty); }
        set { SetValue(WhiteCandleFillProperty, value); }
    }

    public static readonly DependencyProperty WhiteCandleFillProperty =
        DependencyProperty.Register("WhiteCandleFill", typeof(Brush), typeof(CandleStickPointMarker), new UIPropertyMetadata(Brushes.White));



    public Brush WhiteCandleStroke
    {
        get { return (Brush)GetValue(WhiteCandleStrokeProperty); }
        set { SetValue(WhiteCandleStrokeProperty, value); }
    }

    public static readonly DependencyProperty WhiteCandleStrokeProperty =
        DependencyProperty.Register("WhiteCandleStroke", typeof(Brush), typeof(CandleStickPointMarker), new UIPropertyMetadata(Brushes.DarkGray));



    public Brush BlackCandleFill
    {
        get { return (Brush)GetValue(BlackCandleFillProperty); }
        set { SetValue(BlackCandleFillProperty, value); }
    }
    public static readonly DependencyProperty BlackCandleFillProperty =
        DependencyProperty.Register("BlackCandleFill", typeof(Brush), typeof(CandleStickPointMarker), new UIPropertyMetadata(Brushes.Black));
    public Brush BlackCandleStroke
    {
        get { return (Brush)GetValue(BlackCandleStrokeProperty); }
        set { SetValue(BlackCandleStrokeProperty, value); }
    }

    public static readonly DependencyProperty BlackCandleStrokeProperty =
        DependencyProperty.Register("BlackCandleStroke", typeof(Brush), typeof(CandleStickPointMarker), new UIPropertyMetadata(Brushes.Gray));
    public CoordinateTransform Transform { get; set; }
    public double High
    {
        get { return (double)GetValue(HighProperty); }
        set { SetValue(HighProperty, value); }
    }

    public static readonly DependencyProperty HighProperty =
        DependencyProperty.Register("High", typeof(double), typeof(CandleStickPointMarker), new UIPropertyMetadata(0.0));

    public double Low
    {
        get { return (double)GetValue(LowProperty); }
        set { SetValue(LowProperty, value); }
    }

    public static readonly DependencyProperty LowProperty =
        DependencyProperty.Register("Low", typeof(double), typeof(CandleStickPointMarker), new UIPropertyMetadata(0.0));


    public double Open
    {
        get { return (double)GetValue(OpenProperty); }
        set { SetValue(OpenProperty, value); }
    }

    public static readonly DependencyProperty OpenProperty =
        DependencyProperty.Register("Open", typeof(double), typeof(CandleStickPointMarker), new UIPropertyMetadata(0.0));


    public override void Render(System.Windows.Media.DrawingContext dc, Point screenPoint)
    {
        Point screenOpen = GetScreenPoint(Open,screenPoint.X);
        Point screenHigh = GetScreenPoint(High,screenPoint.X);
        Point screenLow = GetScreenPoint(Low, screenPoint.X);
        //screenPoint is the CLOSE by gentleman agreement.
        var close = screenPoint.ScreenToData(Transform).Y;
        Pen strokePen;
        if (Open >= close) // black
        {
            strokePen = new Pen(BlackCandleStroke, CandlestickStrokeWidth);
            var h = -screenOpen.Y + screenPoint.Y;
            Rect blkRect = new Rect(screenPoint.X - CandlestickWidth / 2, screenOpen.Y, CandlestickWidth, h);                       
            dc.DrawRectangle(BlackCandleFill,strokePen, blkRect);
            dc.DrawLine(strokePen, screenLow, screenPoint);
            dc.DrawLine(strokePen, screenHigh, screenOpen);
        }
        else // white
        {
            strokePen=new Pen(WhiteCandleStroke, CandlestickStrokeWidth);
            var h = screenOpen.Y - screenPoint.Y;
            Rect whtRect = new Rect(screenPoint.X - CandlestickWidth / 2, screenPoint.Y, CandlestickWidth, h);
            dc.DrawRectangle(WhiteCandleFill, strokePen, whtRect);
            dc.DrawLine(strokePen, screenLow, screenOpen);
            dc.DrawLine(strokePen, screenHigh, screenPoint);
        }
    }

    private Point GetScreenPoint(double Open,double screenX)
    {
        Point screen = new Point(0, Open);
        return new Point(screenX,screen.DataToScreen(Transform).Y);
    }
}

}

Answer 1

I don’t know if this can help you much, but I suppose the candlestick marker should be similar to a rectangle marker.
The code below shows how I created a rectangle marker in D3 (actually a square), using the Polygon class, in a similar way to the CircleElementPointMarker, with the tooltip functionality working.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Shapes;
using System.Windows.Media;

namespace Microsoft.Research.DynamicDataDisplay.PointMarkers
{
    /// <summary>Adds Rectangle element at every point of graph</summary>
    public class RectangleElementPointMarker : ShapeElementPointMarker
    {
        Polygon Rectangle;

        public override UIElement CreateMarker()
        {
            Rectangle = new Polygon();
            Rectangle.Stroke = (Pen != null) ? Pen.Brush : Brushes.White;
            Rectangle.StrokeThickness = (Pen != null) ? Pen.Thickness : 0;
            Rectangle.Fill = Fill;
            Rectangle.HorizontalAlignment = HorizontalAlignment.Center;
            Rectangle.VerticalAlignment = VerticalAlignment.Center;
            Rectangle.Width = Size;
            Rectangle.Height = Size;

            Point Point1 = new Point(-Rectangle.Width / 2, -Rectangle.Height / 2);
            Point Point2 = new Point(-Rectangle.Width / 2, Rectangle.Height / 2);
            Point Point3 = new Point(Rectangle.Width / 2, Rectangle.Height / 2);
            Point Point4 = new Point(Rectangle.Width / 2, -Rectangle.Height / 2);
            PointCollection myPointCollection = new PointCollection();
            myPointCollection.Add(Point1);
            myPointCollection.Add(Point2);
            myPointCollection.Add(Point3);
            myPointCollection.Add(Point4);
            Rectangle.Points = myPointCollection;

            if (!String.IsNullOrEmpty(ToolTipText))
            {
                ToolTip tt = new ToolTip();
                tt.Content = ToolTipText;
                Rectangle.ToolTip = tt;
            }

            return Rectangle;
        }

        public override void SetPosition(UIElement marker, Point screenPoint)
        {

            Canvas.SetLeft(marker, screenPoint.X - Size / 2);
            Canvas.SetTop(marker, screenPoint.Y - Size / 2);
        }
    }
}

The code was compiled it on .NET 4.0, VS2010