topic Re: Buffer Distance in ArcGIS API for Silverlight Questions

Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:09 GMT

I have a buffer working off of a Query.
A query runs finding a Parcel
That selected feature then is used to run a buffer that selects another set of Feature within that buffer
It then returns them to a listbox

NOTE: everything works great...Just trying to figure out how if I can retrieve the distance each feature is to the buffer centerpoint.

How do I return the Buffer distance for each feature and put the distance in the listbox.
Is there something that I can do in the xaml below, or do I have to get the value in the vb code first?
Once that is gotten can I sort the values in the listbox Ascending via this buffer distance?

<TextBlock Foreground="White" Margin="0,4,0,0" VerticalAlignment="Center" Text="{Binding BUFFER_DISTANCE}" SORT="ASCENDING" />

Is this even possible with the Buffer? I assume that its measuring the distance in order to determine if its inside the Buffer specified distance.....

Thanks

<ListBox.ItemTemplate>
     <DataTemplate>
           <StackPanel Orientation="Horizontal" VerticalAlignment="Center" >
                    <!-- QUERY -->
                    <StackPanel Margin="1">
                            <TextBlock Foreground="White" Margin="0,4,0,0" VerticalAlignment="Center" Text="{Binding Attributes[TYPE]}"/>
                     </StackPanel>
                     <StackPanel Margin="5,0,0,0" Orientation="Vertical">
                             <TextBlock Foreground="White" Text="{Binding Attributes[CITY_NAME], StringFormat='City Name: \{0\}'}" >
                                      <TextBlock.Effect>
                                              <DropShadowEffect/>
                                      </TextBlock.Effect>
                             </TextBlock>
                             <TextBlock Foreground="White" Text="{Binding Attributes[POP1990], StringFormat='Population: \{0\}'}"  >
                                      <TextBlock.Effect>
                                              <DropShadowEffect/>
                                      </TextBlock.Effect>
                             </TextBlock>
                        </StackPanel>
                    </StackPanel>
              </DataTemplate>
       </ListBox.ItemTemplate>
</ListBox>

Re: Buffer Distance

JenniferNery — Sun, 12 Dec 2021 16:11:11 GMT

This Text="{Binding BUFFER_DISTANCE}" will work if you add graphic Attribute with Key 'BUFFER_DISTANCE.' Yes, this need to be added in code-behind.

You can iterate through the graphics in your GraphicsLayer and calculate the Eucledian distance between buffer point and graphic.Geometry.Extent.GetCenter() and store into the graphic Attribute.

For Each g As var In MyGraphicsLayer.Graphics
 Dim c As MapPoint = g.Geometry.Extent.GetCenter()
 g.Attribute("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)
Next

There is no Sort property on TextBox. If you wish to sort the ListBox contents against this Attribute, you can sort using Linq before setting ItemSource or use CollectionViewSource.

Re: Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:14 GMT

What you are saying makes sense.....I think my application is a bit different...

The user clicks a button that does a search on a value from a textblock.
The Parcel is located adn zoomed to
A buffer is created from that found parcel geometry
The buffer then selects the points within that buffer and returns the results to a listbox.

I am not seeing the location to place the code to calculate the Buffer Distance

            ' DRAW THE BUFFER AND USE THE PARCEL TO CREATE THE INITIAL POINT OF THE BUFFER
            _geometryService = New GeometryService("http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer")
            AddHandler _geometryService.BufferCompleted, AddressOf GeometryService_BufferCompleted2
            AddHandler _geometryService.Failed, AddressOf GeometryService_Failed2

            _queryTask = New QueryTask("http://gis.logis.org/arcgis/rest/services/MG_Test_WGS84/MapServer/1")
            AddHandler _queryTask.ExecuteCompleted, AddressOf QueryTask_ExecuteCompletedBuffer2
            AddHandler _queryTask.Failed, AddressOf QueryTask_Failed2

It seems I would put it here:
For Each selectedGraphic As Graphic In args.FeatureSet.Features
selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
_resultsGraphicsLayer.Graphics.Add(selectedGraphic)
Next selectedGraphic

But then I get confused because I am binding the imagelistbuffer (listbox) here
imageListBuffer.ItemsSource = args.FeatureSet.Features

    Private Sub GeometryService_BufferCompleted2(ByVal sender As Object, ByVal args As GraphicsEventArgs)
        Dim bufferGraphic As New Graphic()
        bufferGraphic.Geometry = args.Results(0).Geometry
        bufferGraphic.Symbol = TryCast(LayoutRoot.Resources("BufferSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
        bufferGraphic.SetZIndex(1)

        _pointAndBufferGraphicsLayer.Graphics.Add(bufferGraphic)

        Dim query As New ESRI.ArcGIS.Client.Tasks.Query()
        query.ReturnGeometry = True
        query.OutSpatialReference = MyMap.SpatialReference
        query.Geometry = bufferGraphic.Geometry
        query.OutFields.Add("*")
        _queryTask.ExecuteAsync(query)
    End Sub


    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

         ' Bind the results to the listbox
        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)
        Next selectedGraphic
    End Sub

Re: Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:17 GMT

I tried this but nothing going on the: GetDistance(bufferPoint,c)

    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

        Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayerBufferResults"), GraphicsLayer)

        For Each g As Graphic In graphicsLayer.Graphics
            Dim c As MapPoint = g.Geometry.Extent.GetCenter()
            g.Attributes("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)
        Next

        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

        Next selectedGraphic

    End Sub

Re: Buffer Distance

dotMorten_esri — Wed, 26 Jan 2011 20:00:20 GMT

Isn't it the args.FeatureSet.Features that you want to add the attribute to, and not the graphics layer? (since this is what you bind to the listbox).

Re: Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:19 GMT

I tried this as well just didnt put it in the forum...
I am having a problem I think because the params on the Sub are args As QueryEvent and geometry is not a member of ESRI Tasks.QueryEventArgs
So I cant see how to get teh geometry from the center of each feature

Do I need to do this in a different method or change the Sub Params?
This the only sub tht I can think of placing this data as this is where i am binding the results to the listbox..


    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)
        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As MapPoint = args.Geometry.Extent.GetCenter()
            args.Attributes("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)

        Next selectedGraphic

Then tried this: But the GetDistance errors out saying that GetDistance and bufferPoint are not declared...

        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As MapPoint = selectedGraphic.Geometry.Extent.GetCenter()
            selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)

        Next selectedGraphic

.I cannot see the solution here..anyone? THanks

uggggggggggggggggggggg

Re: Buffer Distance

JayKappy — Thu, 27 Jan 2011 20:30:28 GMT

Am I wasting my time by doing this here in the ... if I am even tryign this in the righ location....or even trying to do it correctly

Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

It seems that GetDistance is not an option

Re: Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:22 GMT

I tried this as well....adding
ESRI.ArcGIS.Client.Geometry.MapPoint

instead of just MapPoint...keeps telling me that GetDistance and bufferPoint not defined.

    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As ESRI.ArcGIS.Client.Geometry.MapPoint = selectedGraphic.Geometry.Extent.GetCenter()
            selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)
        Next selectedGraphic

    End Sub

Is GetDistance supposed to be a function that I am passing 'c' to in order find the distance?
Seems the way I have things set up it cant find the Buffer Point???? only the c (the parcel center point) is defined.
The center point of the buffer was defined in an ealier sub routine...

Re: Buffer Distance

JayKappy — Mon, 31 Jan 2011 11:49:50 GMT

I take it I hit my question limit....wish I had another location to ask questions....I know that I am close here...thanks anyway...although still open for help

Re: Buffer Distance

JayKappy — Sun, 12 Dec 2021 16:11:25 GMT

Io think that I can get the Buffer Graphics center like this: See RED below, BUT its not in the correct Sub Routine...
I need to get that center location to the Private Sub QueryTask_ExecuteCompletedBuffer2 in order to calculate the Distance from the Buffer center to the features found inside the buffer.

    Private Sub GeometryService_BufferCompleted2(ByVal sender As Object, ByVal args As GraphicsEventArgs)
        Dim bufferGraphic As New Graphic()
        bufferGraphic.Geometry = args.Results(0).Geometry
        bufferGraphic.Symbol = TryCast(LayoutRoot.Resources("BufferSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
        bufferGraphic.SetZIndex(1)

        _pointAndBufferGraphicsLayer.Graphics.Add(bufferGraphic)

        Dim bp As ESRI.ArcGIS.Client.Geometry.MapPoint = bufferGraphic.Geometry.Extent.GetCenter()        

        Dim query As New ESRI.ArcGIS.Client.Tasks.Query()
        query.ReturnGeometry = True
        query.OutSpatialReference = MyMap.SpatialReference
        query.Geometry = bufferGraphic.Geometry
        query.OutFields.Add("*")
        _queryTask.ExecuteAsync(query)
    End Sub

    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As ESRI.ArcGIS.Client.Geometry.MapPoint = selectedGraphic.Geometry.Extent.GetCenter()
            selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(bp, c)

        Next selectedGraphic

    End Sub

Re: Buffer Distance

JayKappy — Mon, 31 Jan 2011 18:43:58 GMT

......................................

Re: Buffer Distance

JayKappy — Sat, 11 Dec 2021 10:23:21 GMT

Jenniferdnery's example early on is what I am going on...

For Each g As var In MyGraphicsLayer.Graphics
 Dim c As MapPoint = g.Geometry.Extent.GetCenter()
 g.Attribute("BUFFER_DISTANCE") = GetDistance(bufferPoint, c)
Next

I converted this to the selectedGraphic

selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(bp, c)

I was having issues with getting both values (buffer point, and the feature point) in the same location to calculate the distance. I was able to do that below by creating a global varaible and setting that and then retrieveing that in the second sub...

BUT again my problem still lies on this: Where "GetDistance" is not declared...Is this beign done under teh wrong parameters? (QueryEventArgs)

Hopign that soemone has some thoughts....Guess this is not going to work....keeps telling me that the variable that I am setting: Value type Strign cannot be converted to MapPoint

selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(_XYLocationBuffer, c)


    Private _XYLocation As String = ""




    Private Sub GeometryService_BufferCompleted2(ByVal sender As Object, ByVal args As GraphicsEventArgs)
        Dim bufferGraphic As New Graphic()
        bufferGraphic.Geometry = args.Results(0).Geometry
        bufferGraphic.Geometry.SpatialReference = MyMap.SpatialReference
        bufferGraphic.Symbol = TryCast(LayoutRoot.Resources("BufferSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
        bufferGraphic.SetZIndex(1)

        _pointAndBufferGraphicsLayer.Graphics.Add(bufferGraphic)

       ' Find the Center point of the buffer       
          Dim bp As ESRI.ArcGIS.Client.Geometry.MapPoint = bufferGraphic.Geometry.Extent.GetCenter()
 ' Set the Buffer Variable for the Center Point of the buffer       
        _XYLocation = Nothing
        _XYLocation = bp.ToString

        Dim query As New ESRI.ArcGIS.Client.Tasks.Query()
        query.ReturnGeometry = True
        query.OutSpatialReference = MyMap.SpatialReference
        query.Geometry = bufferGraphic.Geometry
        query.OutFields.Add("*")
        _queryTask.ExecuteAsync(query)
    End Sub

    Private Sub QueryTask_ExecuteCompletedBuffer2(ByVal sender As Object, ByVal args As QueryEventArgs)

        Dim featureSet As FeatureSet = args.FeatureSet
        imageListBuffer.ItemsSource = args.FeatureSet.Features

        ' Set the Buffer Variable for the Center Point of the buffer        
         Dim _XYLocationBuffer As String = Nothing
        _XYLocationBuffer = _XYLocation.ToString


        If args.FeatureSet.Features.Count < 1 Then
            MessageBox.Show("No features found")
            Return
        End If
        For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As ESRI.ArcGIS.Client.Geometry.MapPoint = selectedGraphic.Geometry.Extent.GetCenter()
            MessageBox.Show(c.ToString)
            selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(_XYLocationBuffer, c)

        Next selectedGraphic

    End Sub

Also tryign this example: http://help.arcgis.com/en/webapi/javascript/arcgis/help/jssamples_start.htm#jssamples/util_distance.html

            Dim distParams = New ESRI.tasks.DistanceParameters()
            distParams.distanceUnit = ESRI.tasks.GeometryService.UNIT_STATUTE_MILE
            distParams.geometry1 = pointA  '<--- your Point A geometry
            distParams.geometry2 = pointB  '<--- your Point B geometry
            distParams.geodesic = True

            GeometryService.distance(distParams,function(distance))

Re: Buffer Distance

JayKappy — Sat, 11 Dec 2021 10:23:23 GMT

I am now getting is results back, right now I dont care if the value is not correct distance or not...

The MessageBox below shows a value...but for some reason I cant Bind the value to the Listbox...
The BUFFER_DISTANCE is not a field or anything....It does not exist...I am just trying to create this temporarly to hold the distance value....
Can I do this....Does this make sence....
Any thoughts on why the value is not reflecting in the Listbox?
The other two attributes show up fine...

    For Each selectedGraphic As Graphic In args.FeatureSet.Features
            selectedGraphic.Symbol = TryCast(LayoutRoot.Resources("DefaultMarkerSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            _resultsGraphicsLayer.Graphics.Add(selectedGraphic)

            Dim c As ESRI.ArcGIS.Client.Geometry.MapPoint = selectedGraphic.Geometry.Extent.GetCenter()
            MessageBox.Show(c.ToString)

            selectedGraphic.Attributes("BUFFER_DISTANCE") = GetDistance(_XYLocationBuffer, c)

            MessageBox.Show(selectedGraphic.Attributes("BUFFER_DISTANCE"))

        Next selectedGraphic

<ListBox.ItemTemplate>
   <DataTemplate>
       <StackPanel Orientation="Horizontal" VerticalAlignment="Center" >
           <StackPanel Margin="1">
                <TextBlock Foreground="White" Margin="0,4,0,0" VerticalAlignment="Center" Text="{Binding Attributes[TYPE]}"/>
           </StackPanel>
           <StackPanel Margin="5,0,0,0" Orientation="Vertical">
                  <TextBlock Foreground="White" Text="{Binding Attributes[NAME], StringFormat='Name:    \{0\}'}" />
                  <TextBlock Foreground="White" Text="{Binding BUFFER_DISTANCE, StringFormat='Distance: \{0\}'}" />
            </StackPanel>
         </StackPanel>
      </DataTemplate>
   </ListBox.ItemTemplate>
</ListBox>

Re: Buffer Distance

JayKappy — Tue, 01 Feb 2011 17:33:33 GMT

Got it...think to syntax I was using was incorrect.....

Not Working:

<TextBlock Foreground="White" Text="{Binding BUFFER_DISTANCE, StringFormat='Distance: \{0\}'}" >

Working

<TextBlock Foreground="White" Text="{Binding Attributes[BUFFER_DISTANCE], StringFormat='Distance: \{0\}'}" >

ANYONE INTERESTED IN WHAT I DID OR WANT THE CODE PLEASE FEEL FREE TO CONTACT ME.

THANK YOU ALL FOR YOUR HELP.......SORRY FOR THE BARAGE OF QUESTIONS....KNOW THAT THIS IS NOT A FORUM FOR EVERYONE WRITE CODE FOR ANOTHER PERSON....BUT I DO APPRECIATE ALL YOUR THOUGHTS AND COMMENTS.....

Outline of what I did if anyone is interested...

User Input Box for Parcel
Finds Parcel and highlights it, zooms to it, populates list box with Parcel Info
In the mean time it Does a Buffer on the Parcels geomoetry
Finds features (users choosing) that are within that buffer and creates graphics on the map
The values from these found features in the buffer are also displayed in a listbox with their Attrbiutes and the DISTANCE FROM THE BUFFER CENTER.

The VERY last part of the explination above is what this entry was for....To simply calculate the DISTANCE from the center of the BUFFER.

Re: Buffer Distance

RobChouinard — Tue, 08 Feb 2011 19:48:06 GMT

I have a similar issue where I want to get distance from a point to multiple points. Where did you find the GetDistance() method listed on your posts? I'm thinking this method isn't built into the API. Did you have to use the GeometryService for each point you wanted to get the distance to?

Thanks,
Rob

Re: Buffer Distance

JenniferNery — Sat, 11 Dec 2021 10:23:26 GMT

GetDistance() in this post is not yet implemented.

        private double GetDistance(MapPoint a, MapPoint b)
        {
            if (a == null || b == null) return 0;
            return Math.Sqrt(Math.Pow(a.X - b.X, 2) + Math.Pow(a.Y - b.Y, 2));
        }

Re: Buffer Distance

JayKappy — Sat, 11 Dec 2021 10:23:29 GMT

I have a similar issue where I want to get distance from a point to multiple points. Where did you find the GetDistance() method listed on your posts? I'm thinking this method isn't built into the API. Did you have to use the GeometryService for each point you wanted to get the distance to?

Thanks,
Rob

This is what I used:

Not you can change and return from Double to Integer on the Function ( As Integer, As Double)

    Private Function GetDistance(ByVal start As MapPoint, ByVal [end] As MapPoint) As Integer
        Dim deltaX As Double = 0
        Dim deltaY As Double = 0

        deltaX = start.X - [end].X
        deltaY = start.Y - [end].Y

        Return Math.Sqrt((deltaX * deltaX) + (deltaY * deltaY))

    End Function

Yes on the Geometry service.....I can give you my code...but here is what I did...

I do a search
it finds a parcel (polygon)
Zooms to that parcel.
Creates a Buffer graphic based ont he geomoetry of that Parcel (set the buffer point to global variable, very important)
Queries for the points that fall in that buffer
in a for each loop passes the location and buffer center point to the function which calculates distance
Finally bind the results to a listbox.

If you want help...contact me....jaykappy@yahoo.com

Re: Buffer Distance

RobChouinard — Mon, 14 Feb 2011 14:14:49 GMT

Thanks, I used the C# code that jenniferdnery posted. I didn't realize it would be that simple 🙂