HitTest a polyline

Hi,
how can I get the segment of a polyline when I hittested it?
I'm using LT15 with VB.NET
Thanks!

Hello,

The following code shows how to get the segment of a AnnPolylineObject when you Hittest it:
+------------------+

Private Sub RasterImageViewer1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles RasterImageViewer1.MouseMove
' perform hit-testing and update the status bar
If Not RasterImageViewer1.Image Is Nothing Then
If Not AutomationAnn.Container Is Nothing Then

Dim pt As AnnPoint = New AnnPoint(e.X, e.Y, AnnUnit.Pixel)
Dim obj As AnnObject = AutomationAnn.Container.HitTest(pt, 2)
Dim PolylineObject As AnnPolylineObject
Dim i As Integer

If Not obj Is Nothing Then

Text = String.Format("Type: {0}, Name: {1}, Value: {2}", obj.GetType().Name, obj.Name, obj.HitTest(pt, 2))

If TypeOf (obj) Is AnnPolylineObject Then
PolylineObject = obj
Text = pt.X.ToString() _
+ " , " + pt.Y.ToString()

For i = 0 To PolylineObject.Points.Count - 1
Dim P1 As New AnnPoint
P1 = PolylineObject.Points(i)

Dim P2 As New AnnPoint
If i = PolylineObject.Points.Count - 1 Then
P2 = P1
Else
P2 = PolylineObject.Points(i + 1)
End If

'Now, check if the pt point between p1 and p2
'If pt is between p1 and p2, then you can
'get the segment by using the
'points p1 and p2
Next

End If
Else
Text = String.Empty
End If
End If
End If

End Sub
+------------------+

Please let me know if this helps.

Thanks,
Maen Badwan
LEADTOOLS Technical Support

Hi,
but my question is how can do for determinig if pt is between p1 and p2, I just know the use of PolylineObject collection.
Thanks!!!

Hi,

I did the same thing, but I am not getting the expected result.

I have two approaches for the given problem.

1. Find the slope of two lines and match, they should be same if pointx lies on a line (StartPoint,EndPoint)

2. Find the slope and intercept. Then satify the straightline equation Y= mX +c

But both options are not working. Please help me, am I missing any trick here.

Please find my code, and suggest If I am doing anything wrong

private void DoHitTest(MouseEventArgs e)
        {
            float tolerance = 0.001f;
            AnnPoint pointTobeSearched = new AnnPoint(
                        (e.X + Viewer.ScrollPosition.X) / (float)Viewer.CurrentYScaleFactor,
                        (e.Y + Viewer.ScrollPosition.Y) / (float)Viewer.CurrentYScaleFactor);

            for (int i = 0; i < (PickedPoints.Count - 2); i++)
            {
                AnnPoint Point1 = this.PickedPoints[i];
                AnnPoint Point2 = this.PickedPoints[i + 1];

                float slopeFullLine = (Point2.Y - Point1.Y) / (Point2.X - Point1.X);
                float slopeTillHitPoint = (pointTobeSearched.Y - Point1.Y) / (pointTobeSearched.X - Point1.X);

                //below not working (Comparison of both slopes.
                if ((slopeFullLine - slopeTillHitPoint) <= tolerance)
                {
                    IndexToBeInserted = i;
                    break;
                }

                if ((Point2.X - Point1.X) <= tolerance)  // Vertical line.
                {
                    this.IndexToBeInserted = i;
                }

                float M = (Point2.Y - Point1.Y) / (Point2.X - Point1.X); // Slope
                float C = -(M * Point1.X) + Point1.Y; // Y intercept

                // Checking if (x, y) is on the line passing through the end points. (not working)
                if (Math.Abs(pointToBeSearched.Y - ((M * pointToBeSearched.X) + C)) <= tolerance)
                {
                    this.IndexToBeInserted = i;
                }

            }

If you're having difficulty with the calculations, I can try to help you if you put your code in a small test project (not your full application) and send it to me. You can either post the test project here or email it to support@leadtools.com
If you post it here, do not use the preview feature when attaching.

In either case, make sure to put all attachments in a ZIP or RAR file to ensure our server delivers them correctly.

Maen Badwan
LEADTOOLS Technical Support

Hi Maen Badwan

I am using a different approach now. I am trying to use IsOutlineVisible Method of Graphics path. But still I am failed :(

I am creating a path using two adjacent points. Then finding the hit point in the given path. Please find my code below and please help me out..

if (e.Button == MouseButtons.Left)

{

CurvePolyLine obj = ObjectTemplate as CurvePolyLine;

if (obj.CurrentMode == Common.FrmCurveEditorMode.EditCurve)

{

PointF hitPoint = new PointF(e.X,e.Y);

for (int i = 0; i < (obj.PickedPoints.Count - 2); i++)

{

GraphicsPath graphicsPath = new GraphicsPath();

AnnPoint annPoint1 = obj.PickedPoints[i];

AnnPoint startPoint = annPoint1.ConvertTo(Container.UnitConverter, AnnUnit.Pixel);

AnnPoint annPoint3 = obj.PickedPoints[i+1];

AnnPoint endPoint = annPoint3.ConvertTo(Container.UnitConverter, AnnUnit.Pixel);

graphicsPath.AddLine(startPoint.ToPointF(), endPoint.ToPointF());

//Needs to be created

Matrix m = new Matrix();

float width = obj.Pen.Width.Converted(Container.UnitConverter,AnnUnit.Pixel);

Pen p = new Pen(System.Drawing.Color.Black,width);

//graphicsPath.Transform(m);

bool b = graphicsPath.IsOutlineVisible(hitPoint, p);

graphicsPath.Widen(p);

p.Dispose();

 

if (b)

{

MessageBox.Show("Found");

}

if (graphicsPath.IsVisible(hitPoint))

{

MessageBox.Show("Found");

}

 

}

}

 

I am not a getting the transformation matrix... but I am sure something I am doing wrong doing there. Please please help

Hi

I am attaching a sample project with my both approaches

Approach 1: Satisfying the line equation.

Approach 2: Using IsOutlineVisible of Graphics Path

 

Please help me out.

Thanks

Raj

Raj,

I did it using the slope approach. I covered most cases except the vertical line. I am attaching the modified project.

Thanks,
Maen Badwan
LEADTOOLS Technical Support