Annotation Anchor is responsible for too much.

[TRVRSE]

I have 2 design goals. Given the desired location of the the top left of my Annotation, draw an annotation at that point. Also, draw a line from the center of the annotation to the target point. The location could be specified in ScreenCoordinates or AxisValues. Example: Adding an annotation at Screen Coords (.6,.6) means the top left corner of the annotation is at (.6,.6) and the line draws to the center of the annotation.

Any tips on this? I've tried setting the Anchor to (0,0). This will get me an annotation drawn at the correct location, but the line draws to the corner of the annotations. I've tried setting the anchor to (.5,.5), and the line draws as desired, but the location is off.

I've thought about binding to the actualwidth and height and converting, but these are properties do not exist. Any tips?

[ArctionPasi]

Anchor works also as center point of rotation

The actual width and height in pixels can be calculated as instructed here:
http://www.arction.com/forum/viewtopic.php?f=16&t=404

You should set LocationCoordinateSystem = ScreenCoordinates and set the LocationScreenCoords values as to match the position you need to show it.

In Anchor, 0 means left or top, and 1 means right or bottom. So it's a relative factor.

[TRVRSE]

Im requesting that the arrow source point and the anchor become divorced. I'd like to be able to keep my anchor in the top left corner of my annotation. I'd also like to draw my arrow from the center, or from the corner nearest the target point. Would you add such a feature?

[ArctionPasi]

I'm wondering if Style = Callout suits your purpose directly?

We would rather not make the modification because there's too many properties in Annotations already, and we'd have to program all mouse interactivity and for editing the line end point as well... Easily talking about week of work for a minor feature.

How about just using two annotations? One with Style = Rectangle and another with Style = Arrow. Here's the code to accomplish this:

Code: Select all

public partial class MainWindow : Window
    {
        LightningChartUltimate m_chart; 
        AnnotationXY m_annotArrow;
        AnnotationXY m_annotRectangle; 
 
        public MainWindow()
        {
            InitializeComponent();

            CreateChart();

            m_chart.MouseDoubleClick += new MouseButtonEventHandler(m_chart_MouseDoubleClick);

        }

        void m_chart_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            m_chart.BeginUpdate();

            ViewXY v = m_chart.ViewXY;
            AxisX xAxis = v.XAxes[0];
            AxisY yAxis = v.YAxes[0];

            v.Annotations.Clear(); 

            //Arrow 
            m_annotArrow = new AnnotationXY(v, xAxis, yAxis);
            m_annotArrow.Style = AnnotationStyle.Arrow;
            m_annotArrow.LocationCoordinateSystem = CoordinateSystem.ScreenCoordinates;
            m_annotArrow.TextStyle.Visible = false;
            m_annotArrow.ArrowLineStyle.Color = Colors.Red;
            m_annotArrow.AnchorAdjustByMouse = false;
            m_annotArrow.MoveByMouse = false; 
            m_annotArrow.ResizeByMouse = false;
            m_annotArrow.RotateByMouse = false;
            m_annotArrow.TargetMoveByMouse = false; 
            m_annotArrow.TargetAxisValues.SetValues(2, 0);
            v.Annotations.Add(m_annotArrow);



            //Rectangle 
            m_annotRectangle = new AnnotationXY(v, xAxis, yAxis);
            m_annotRectangle.Style = AnnotationStyle.Rectangle;
            m_annotRectangle.LocationCoordinateSystem = CoordinateSystem.AxisValues;
            m_annotRectangle.LocationAxisValues.SetValues(3, 7);
            m_annotRectangle.Anchor.SetValues(0, 0); //Top-left 
            m_annotRectangle.ResizeByMouse = false;
            m_annotRectangle.RotateByMouse = false;
            m_annotRectangle.TargetMoveByMouse = false;
            m_annotRectangle.AnchorAdjustByMouse = false; 
            m_annotRectangle.MovedByMouse += new MouseEventHandler(annotRectangle_MovedByMouse);
            m_annotRectangle.AnchorAdjustedByMouse += new AnnotationBase.AnchorAdjustedByMouseHandler(m_annotRectangle_AnchorAdjustedByMouse);
            m_annotRectangle.Text = "This is an \nannotation";

            v.Annotations.Add(m_annotRectangle);

            UpdateArrow();
            
            m_chart.EndUpdate(); 


        }

        void CreateChart()
        {
            m_chart = new LightningChartUltimate();
            gridMain.Children.Add(m_chart);
        }

        void m_annotRectangle_AnchorAdjustedByMouse(AnnotationBase sender, PointFloat oldAnchor, PointFloat newAnchor, ref bool cancelRendering)
        {
            UpdateArrow(); 
        }

        void annotRectangle_MovedByMouse(object sender, MouseEventArgs e)
        {
            UpdateArrow(); 
        }

        void UpdateArrow()
        {
   
            //Reposition the arrow annotation's Location 
            PointInt size = m_chart.MeasureText(m_annotRectangle.Text, m_annotRectangle.TextStyle.Font);
            int iRectWidth = size.X + m_annotRectangle.AutoSizePadding * 2; 
            int iRectHeight = size.Y + m_annotRectangle.AutoSizePadding * 2; 

            //Rectangle annotation's location coordinate 
            int iX = (int) m_chart.ViewXY.XAxes[0].ValueToCoord(m_annotRectangle.LocationAxisValues.X);
            int iY = (int) m_chart.ViewXY.YAxes[0].ValueToCoord(m_annotRectangle.LocationAxisValues.Y);

            //Boundaries 
            int iLeft = iX  - (int)((double)(m_annotRectangle.Anchor.X) * (double)iRectWidth);
            int iTop = iY - (int)((double)(m_annotRectangle.Anchor.Y) * (double)iRectHeight);
            int iRight = iX + iRectWidth; 
            int iBottom = iY + iRectHeight;

            //Use this for center of annotation
            //m_annotArrow.LocationScreenCoords.SetValues((iLeft + iRight) / 2, (iTop + iBottom) / 2); 

            //Use this for center of bottom edge 
            m_annotArrow.LocationScreenCoords.SetValues((iLeft + iRight) / 2, iBottom); 


        }
    }

You may want to call UpdateArrow() in chart.SizeChanged and axis.RangeChanged event handlers too.

Chart with rectangle annotation and second arrow annotation with custom placement.

Chart with annotation.JPG (109.64 KiB) Viewed 6229 times

I hope this helps