question to layer (custom provider)

[Ulrich Fiege]

We have the following use-case:

We´ve build a custom map provider, that works. There is one problem:
An image with the labels of the map have to be overlayed of the hole
map-view and the label-image have to be requested and updated at every zooming- or panning-action.
Currently we load the label-image into an Image-control of an informationlayer.
The events "Zoomchanged" or "Centerchanged" are not useful to update the label-image, because
they won´t be triggered at the end of the action.
Are there any other events, like "Zooming-end", "Panning-end" or "Mapview-changed"?

We tried to use the tilelayer, too. But we can´t change the tilesize-property, because
it´s readonly. Is it possible to change the tilesize of a tilelayer?

Best regards

[Justin White]

I agree with Ulrich - we need a couple more events like he mentioned - ZoomEnd and PanEnd would

My specific case is a little different - I am updating UIElements that are positioned based and found that using the CenterChanged event doesn't quite work because it fires and then the map still moves slower and slower till it stops to not create a jarring stopping effect. Really nice to look at but again - means that the positions are slightly off because of when the event fires...

Maybe I missed something?

Excellent control by the way!

Justin

[Andrey]

Hi,

If I quite get your points you are trying to create something like crosshair at the center of the map. I agree that using of the CenterChanged event isn't good enough for this purpose, because it may produce some strange visual effects when panning with mouse. It occurs because this event fires few times when you move mouse when left button is pressed.

We have crosshair control in our plans for 2010.Q2 release. We also will include some new events which can simplify handling the situations like this.

By the way, if you need something that is always centered over the map you can simply put a control with transparent background in the same container as RadMap and make it centered -- vertically and horizontally  (like it is done in the example below - green ring).

To Justing: I've checked how the FrameworkElements are positioned on the map using the CenterChanged event. They are placed right where they should be even after sprig animation. Please, make sure the elements are aligned correctly.You can find below a simple code which adds element to the information layer when map center is changed.

<UserControl x:Class="Telerik.Silverlight.RadMap.MainPage"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:map="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.DataVisualization"
             xmlns:layer="clr-namespace:Telerik.Windows.Controls.Map;assembly=Telerik.Windows.Controls.DataVisualization"
             Width="800"
             Height="600">
    <Grid x:Name="LayoutRoot">
        <Grid.Resources>
            <DataTemplate x:Key="RingTemplate">
                <Grid Width="14" Height="14">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="14" />
                        <ColumnDefinition Width="Auto" />
                    </Grid.ColumnDefinitions>
                    <layer:MapLayer.HotSpot>
                        <layer:HotSpot X="0.5" Y="0.5" />
                    </layer:MapLayer.HotSpot>
                    <Path Fill="Yellow">
                        <Path.Data>
                            <GeometryGroup>
                                <EllipseGeometry Center="7,7" RadiusX="3" RadiusY="3" />
                                <EllipseGeometry Center="7,7" RadiusX="7" RadiusY="7" />
                            </GeometryGroup>
                        </Path.Data>
                    </Path>
                </Grid>
            </DataTemplate>
        </Grid.Resources>

        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="80*" />
            <ColumnDefinition Width="20*" />
        </Grid.ColumnDefinitions>

        <map:RadMap x:Name="radMap"
                    Center="37.7040701207995,-121.882780875908"
                    ZoomLevel="10"
                    CenterChanged="MapCenterChanged">
            <layer:InformationLayer Name="informationLayer" ItemTemplate="{StaticResource RingTemplate}">
            </layer:InformationLayer>
        </map:RadMap>

        <Grid>
            <Grid Width="14" Height="14" HorizontalAlignment="Center" VerticalAlignment="Center">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="14" />
                    <ColumnDefinition Width="Auto" />
                </Grid.ColumnDefinitions>
                <layer:MapLayer.HotSpot>
                    <layer:HotSpot X="0.5" Y="0.5" />
                </layer:MapLayer.HotSpot>
                <Path Fill="Green">
                    <Path.Data>
                        <GeometryGroup>
                            <EllipseGeometry Center="7,7" RadiusX="3" RadiusY="3" />
                            <EllipseGeometry Center="7,7" RadiusX="7" RadiusY="7" />
                        </GeometryGroup>
                    </Path.Data>
                </Path>
            </Grid>
        </Grid>
    </Grid>
</UserControl>

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.Windows.Resources;
using System.Windows.Data;
using Telerik.Windows.Controls.Map;

namespace Telerik.Silverlight.RadMap
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();

            this.Loaded += new RoutedEventHandler(MainPage_Loaded);
        }

        private void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            BingMapProvider provider = new BingMapProvider(MapMode.Aerial, true, "YOUR Bing Application ID");
            this.radMap.Provider = provider;
        }

        private void MapCenterChanged(object sender, EventArgs e)
        {
            this.informationLayer.Items.Clear();
            this.informationLayer.Items.Add(this.radMap.Center);
        }
    }
}

To Ulrich: I am afraid changing the tile size is not possible.

Regards,
Andrey Murzov
the Telerik team

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[Ulrich Fiege]

Thank you for the example.

It works fine with build in providers like openstreetmapprovider.
But with our custom provider, the informationlayer-item is allways displayed in the left-top-corner.
Please have a look at the attached custom provider class code.
Could there probably a problem with "SpatialReference" is set to "MercatorProjection"?
This setting is nescessary for our mapserver.

Imports System
Imports System.Windows
Imports System.Windows.Browser
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Text.RegularExpressions
Imports Telerik.Windows.Controls.Map
Imports Telerik.Windows.Controls
Imports System.Text


Public Class XserverTileSource
    Inherits MapProviderBase
    Public Const TILE_SIZE As Integer = 256
    Private _IsInitialized As Boolean
    Private _mapparent As RadMap
    Private baseUrl As String

    'Constructor Called by XAML instanciation; Wait for MapMode to be set to initialize services
    Public Sub New(ByVal baseUrl As String)
        MyBase.New(MapMode.Road, True)
        Me.baseUrl = baseUrl

        MaxZoomLevel = 17
        MinZoomLevel = 1

        _IsInitialized = True
        RaiseEvent InitializeCompleted(Me, Nothing)
    End Sub

    Public Overloads Overrides ReadOnly Property IsInitialized() As Boolean
        Get
            Return _IsInitialized
        End Get
    End Property

    ' <summary>
    ' Gets list of the supported map modes.
    ' </summary>
    ' <returns>List of the supported map modes.</returns>
    Public Overloads Overrides ReadOnly Property SupportedModes() As IEnumerable(Of MapMode)
        Get
        End Get
    End Property


    ' <summary>
    ' Gets value which indicates whether given mode is supported by map provider.
    ' </summary>
    ' <param name="mode">Map mode to check.</param>
    ' <returns>true if given mode is supported. Otherwise - false.</returns>
    Public Overloads Overrides Function IsModeSupported(ByVal mode As MapMode) As Boolean
        Return True
    End Function

    ' <summary>
    ' Gets value which indicates whether labels are supported by the map provider.
    ' </summary>
    Public Overloads Overrides ReadOnly Property IsLabelSupported() As Boolean
        Get
            Return False
        End Get
    End Property

    ' <summary>
    ' MapModeChanged handler.
    ' </summary>
    Protected Overloads Overrides Sub OnMapModeChanged(ByVal oldMode As MapMode, ByVal newMode As MapMode)
        If Not Me.IsSuspended Then
            Me.Initialize()
        End If
    End Sub

    ' <summary>
    ' Initialize provider.
    ' </summary>
    Public Overloads Overrides Sub Initialize()

        'Me._IsInitialized = MyBase.IsInitialized
    End Sub

    ' <summary>
    ' Returns the SpatialReference for the map provider.
    ' </summary>
    Public Overloads Overrides ReadOnly Property SpatialReference() As ISpatialReference
        Get
            Return New MercatorProjection()
        End Get
    End Property

    Public Overloads Overrides ReadOnly Property TileColor() As Color
        Get
            Return Color.FromArgb(255, 255, 254, 185)
        End Get
    End Property

    Public Overloads Overrides Function GetTile(ByVal tileLevel As Integer, ByVal tilePositionX As Integer, ByVal tilePositionY As Integer) As Uri
        If IsInitialized Then
            Dim zoom As Integer = ConvertTileToZoomLevel(tileLevel)

            Dim quadKey As String = TileXYToQuadKey(tilePositionX, tilePositionY, zoom)

            ' Use the quadkey to determine a bounding box for the requested tile
            Dim boundingBox As BBox = QuadKeyToBBox(quadKey)

            ' Get the lat longs of the corners of the box
            Dim lon As Double = XToLongitudeAtZoom(boundingBox.x * TILE_SIZE, 18)
            Dim lat As Double = YToLatitudeAtZoom(boundingBox.y * TILE_SIZE, 18)

            Dim lon2 As Double = XToLongitudeAtZoom((boundingBox.x + boundingBox.width) * TILE_SIZE, 18)

            Dim lat2 As Double = YToLatitudeAtZoom((boundingBox.y - boundingBox.height) * TILE_SIZE, 18)

            Dim x1 As Double, y1 As Double
            Wgs_2_Mercator(lon, lat, x1, y1)
            Dim x2 As Double, y2 As Double
            Wgs_2_Mercator(lon2, lat2, x2, y2)

            ' Url of Http-Handler, that gets back the tiles as png
            Dim xmapUrl As StringString = String.Concat(baseUrl, "?left=", System.Convert.ToInt32(CInt(x1)), "&top=", System.Convert.ToInt32(CInt(y1)), "&right=", _
            System.Convert.ToInt32(CInt(x2)), "&bottom=", System.Convert.ToInt32(CInt(y2)))
            Dim iru As Uri = New Uri(xmapUrl)
            Return iru
        End If
        Return Nothing
    End Function

    Public Shared Sub Wgs_2_Mercator(ByVal xArg As Double, ByVal yArg As Double, ByRef xOut As Double, ByRef yOut As Double)
        Dim lambda As Double, phi As Double
        lambda = xArg
        phi = yArg
        xOut = 6371000.0R * ((Math.PI / 180) * ((lambda) - 0.0R))
        yOut = 6371000.0R * Math.Log(Math.Tan((Math.PI / 4) + (Math.PI / 180) * phi * 0.5))
    End Sub

    ''' <summary>
    ''' Retrieves a quad key from a Virtual Earth tile specifier URL
    ''' </summary>
    ''' <param name="url"></param>
    ''' <returns></returns>
    Public Function GetQuadKey(ByVal url As String) As String
        Dim regex = New Regex(".*tiles/(.+)[.].*")
        Dim match As Match = regex.Match(url)

        Return match.Groups(1).ToString()
    End Function

    ''' <summary>
    ''' Returns the bounding BBox for a grid square represented by the given quad key
    ''' </summary>
    ''' <param name="quadKey"></param>
    ''' <param name="x"></param>
    ''' <param name="y"></param>
    ''' <param name="zoomLevel"></param>
    ''' <returns></returns>
    Public Function QuadKeyToBBox(ByVal quadKey As String, ByVal x As Integer, ByVal y As Integer, ByVal zoomLevel As Integer) As BBox
        Dim c As Char = quadKey(0)

        Dim tileSize As Integer = 2 << (18 - zoomLevel - 1)

        If cc = "0"c Then
            yy = y - tileSize

        ElseIf cc = "1"c Then
            yy = y - tileSize
            xx = x + tileSize

        ElseIf cc = "3"c Then
            xx = x + tileSize
        End If

        If quadKey.Length > 1 Then
            Return QuadKeyToBBox(quadKey.Substring(1), x, y, zoomLevel + 1)
        End If
        Return New BBox(x, y, tileSize, tileSize)
    End Function

    Public Function QuadKeyToBBox(ByVal quadKey As String) As BBox
        Const x As Integer = 0
        Const y As Integer = 262144
        Return QuadKeyToBBox(quadKey, x, y, 1)
    End Function

    ''' <summary>
    ''' Converts radians to degrees
    ''' </summary>
    ''' <param name="d"></param>
    ''' <returns></returns>
    Public Function RadToDeg(ByVal d As Double) As Double
        Return d / Math.PI * 180.0R
    End Function

    ''' <summary>
    ''' Converts a grid row to Latitude
    ''' </summary>
    ''' <param name="y"></param>
    ''' <param name="zoom"></param>
    ''' <returns></returns>
    Public Function YToLatitudeAtZoom(ByVal y As Integer, ByVal zoom As Integer) As Double
        Dim arc As Double = EarthCircumference / ((1 << zoom) * TILE_SIZE)
        Dim metersY As Double = HalfEarthCircumference - (y * arc)
        Dim a As Double = Math.Exp(metersY * 2 / EarthRadius)
        Dim result As Double = RadToDeg(Math.Asin((a - 1) / (a + 1)))
        Return result
    End Function

    ''' <summary>
    ''' Converts a grid column to Longitude
    ''' </summary>
    ''' <param name="x"></param>
    ''' <param name="zoom"></param>
    ''' <returns></returns>
    Public Function XToLongitudeAtZoom(ByVal x As Integer, ByVal zoom As Integer) As Double
        Dim arc As Double = EarthCircumference / ((1 << zoom) * TILE_SIZE)
        Dim metersX As Double = (x * arc) - HalfEarthCircumference
        Dim result As Double = RadToDeg(metersX / EarthRadius)
        Return result
    End Function

    Private Shared Function TileXYToQuadKey(ByVal tileX As Integer, ByVal tileY As Integer, ByVal levelOfDetail As Integer) As String
        Dim quadKey = New StringBuilder()
        For i As Integer = levelOfDetail To 1 Step -1
            Dim digit As Integer = 48
            Dim mask As Integer = 1 << (i - 1)
            If (tileX And mask) <> 0 Then
                digit += 1
            End If
            If (tileY And mask) <> 0 Then
                digit += 1
                digit += 1
            End If
            quadKey.Append(Convert.ToChar(digit))
        Next
        Return quadKey.ToString()
    End Function


    Public Shared Shadows Event InitializeCompleted As EventHandler
End Class

Public Class BBox
    Public x As Integer
    Public y As Integer
    Public width As Integer
    Public height As Integer

    Public Sub New(ByVal x As Integer, ByVal y As Integer, ByVal width As Integer, ByVal height As Integer)
        Me.x = x
        Me.y = y
        Me.width = width
        Me.height = height
    End Sub
End Class

[Andrey]

Hi Ulrich,

The information layer will not arrange its items until the map control is initialized.
The initialization is completed when the InitializeCompleted event of a map provider is raised.
The MyBase.IsInitialized property always returns True and raises this event, but I see that it is commented in your code.

' <summary>
' Initialize provider.
' </summary>
Public Overloads Overrides Sub Initialize()

    'Me._IsInitialized = MyBase.IsInitialized
End Sub

I think you can uncomment it or remove the Initialize method override in order to complete the initialization.

Greetings,
Andrey Murzov
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items.

[Ulrich Fiege]

Hi,

the cod|e "||Me._IsInitialized = MyBase.IsInitialized| " is commented, because it throws an exception:

Message: The object reference was not specified on an object instance.
Stacktrace: at Telerik.Windows.Controls.Map.MapCommandBar.SetupMapStyleCommands()
at Telerik.Windows.Controls.Map.MapCommandBar.OnMapInitialize(RadMap oldMapControl, RadMap newMapControl)
atTelerik.Windows.Controls.Map.MapBaseControl.MapControlChanged(DependencyObject source, DependencyPropertyChangedEventArgs eventArgs)
at Telerik.Windows.PropertyMetadata.<>c__DisplayClass1.<Create>b__0(DependencyObject d, DependencyPropertyChangedEventArgs e)
atSystem.Windows.DependencyObject.RaisePropertyChangeNotifications(DependencyProperty dp, Object newValue, Object oldValue)
at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value, Boolean allowReadOnlySet, Boolean isSetByStyle, Boolean isSetByBuiltInStyle, PropertyInvalidationReason reason)
at System.Windows.DependencyObject.SetValueInternal(DependencyProperty dp, Object value)
at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
at Telerik.Windows.Controls.Map.MapBaseControl.set_MapControl(RadMap value)
at Telerik.Windows.Controls.RadMap.Initialize()
at Telerik.Windows.Controls.Map.TileLayer.ProviderInitializeCompleted(Object sender, EventArgs e)
at Telerik.Windows.Controls.Map.MapProviderBase.get_IsInitialized()
at TestRadmap.XserverTileSource.Initialize()

We can´t remove the initialize method, because it´s "mustoverride".

Greetings

[Andrey]

Hello Ulrich,

The exception occurs because the SupportedModes property returns a Nothing value. Please change it to return empty IEnumerable value like to the following code:

Public Overloads Overrides ReadOnly Property SupportedModes() As IEnumerable(Of MapMode)
    Get
        Dim Modes As List(Of MapMode) = New List(Of MapMode)
        Return Modes
    End Get
End Property

Then un-comment the "Me._IsInitialized = MyBase.IsInitialized" string.

Greetings,
Andrey Murzov
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items.