Scrolling and Zooming

• Jun 07, 2019
• 4 minutes to read

You can use zooming and scrolling to navigate on a map.

• Scrolling a Map
• How to: Enable Circular Scrolling
• Zooming a Map
• How to: Zoom to a Specified Region

Scrolling a Map

The Map control allows scrolling by default. You can enable/disable scrolling using the MapControl.EnableScrolling property.

XAML

<dxm:MapControl EnableScrolling="True">
    <dxm:MapControl.ScrollButtonsOptions>
        <dxm:ScrollButtonsOptions Visible="True"/>
    </dxm:MapControl.ScrollButtonsOptions>     
    <!-- Other Map control's settings. -->
</dxm:MapControl>

The code above uses the following classes and properties:

Class or Property	Description
MapControl.EnableScrolling	Specifies whether scrolling is enabled/disabled.
MapControl.ScrollButtonsOptions	Gets or sets scroll buttons’ options.
ScrollButtonsOptions	Stores scroll buttons’ options.
MapElementOptions.Visible	Specifies scroll buttons’ visibility.

After scrolling is enabled, the map can be scrolled as follows:

• Hover a mouse pointer over a map. Click and hold the left mouse button and drag it in the required direction.

• Use scroll buttons. You can scroll the map in the four directions by clicking the navigation panel’s arrows.

  

• Scroll a map using flick gestures on touchscreen devices.
• Use the MapControl.Scroll method to programmatically scroll a map by a specified offset. The MapControl.CanScroll method checks if the offset is valid.

How to: Enable Circular Scrolling

You can scroll a map endlessly by enabling the Circular Scrolling option. This functionality can be used in maps that have a geographical coordinate system.

The following example shows how to enable Circular Scrolling:

XAML

<dxm:MapControl ZoomLevel="3">
    <dxm:ImageLayer>
        <dxm:BingMapDataProvider BingKey="Your Bing Key Here"/>
    </dxm:ImageLayer>
    <dxm:MapControl.CoordinateSystem>
        <dxm:GeoMapCoordinateSystem CircularScrollingMode="TilesAndVectorItems"/>
    </dxm:MapControl.CoordinateSystem>
</dxm:MapControl>

Use the following classes and properties to enable circular scrolling:

Class or Property	Description
MapControl.CoordinateSystem	Gets or sets a map’s coordinate system.
GeoMapCoordinateSystem	The Map control’s Geographical coordinate system.
GeoMapCoordinateSystem.CircularScrollingMode	Specifies which map items can be circularly scrolled.
CircularScrollingMode	Lists values that indicate items that should be circularly scrolled.

Note that, a map shape should fulfill the following condition to cross the 180th meridian: one or several points’ longitudes should exceed the 180 (-180) limit:

Xaml

<dxm:MapItemStorage>
    <dxm:MapItemStorage.Items>
        <dxm:MapPolygon>
            <dxm:MapPolygon.Points>
                <dxm:GeoPoint Latitude="-10" Longitude="-170"/>
                <dxm:GeoPoint Latitude="-10" Longitude="170"/>
                <dxm:GeoPoint Latitude="10" Longitude="170"/>
                <dxm:GeoPoint Latitude="10" Longitude="-170"/>
            </dxm:MapPolygon.Points>
        </dxm:MapPolygon>
        <dxm:MapPolygon Fill="Orange">
            <dxm:MapPolygon.Points>
                <dxm:GeoPoint Latitude="30" Longitude="170"/>
                <dxm:GeoPoint Latitude="30" Longitude="190"/>
                <dxm:GeoPoint Latitude="40" Longitude="190"/>
                <dxm:GeoPoint Latitude="40" Longitude="170"/>
            </dxm:MapPolygon.Points>
        </dxm:MapPolygon>
    </dxm:MapItemStorage.Items>
</dxm:MapItemStorage>

The code above produces the following image:

Zooming a Map

The zooming functionality is available in the Map control by default. You can enable/disable zooming in maps using the MapControl.EnableZooming property:

XAML

<dxm:MapControl EnableZooming="True">
        <!-- Other Map control's settings. -->
</dxm:MapControl>

You can also use the following classes and properties to configure zooming options:

Class or Property	Description
MapControl.MaxZoomLevel	Gets or sets the Map control’s maximum zoom level.
MapControl.MinZoomLevel	Specifies the Map control’s minimum zoom level.
LayerBase.MaxZoomLevel	Gets or sets the map layer’s maximum zoom level.
LayerBase.MinZoomLevel	Specifies the map layer’s minimum zoom level.
MapControl.MouseWheelZoomingStep	Specifies the zooming step when the zooming using the mouse wheel.
MapControl.ZoomTrackbarOptions	Gets or sets the Zoom Trackbar’s settings.
ZoomTrackbarOptions	Stores the Zoom Trackbar’s settings.

You can zoom a map as follows:

• Use the mouse wheel to zoom a map in or out.

• The Zoom Trackbar allows end users to change a zoom level by clicking plus and minus symbols and moving the track bar’s slider.

  

• Press and hold Shift and Ctrl to select a rectangular area on a map to zoom.

  

• Use the pinch and spread gestures to zoom a map in or out on touchscreen devices.
• You can use the MapControl.Zoom method to zoom a map to the specified zoom level.
• The MapControl.ZoomToRegion method zooms a map to the defined region. Refer to the How to: Zoom to a Specified Region section to learn more.
• Use the MapControl.ZoomToFitLayerItems and MapControl.ZoomToFit methods to zoom to fit items on the map.

How to: Zoom to a Specified Region

The following example shows how to zoom a rectangular area specified by two geographical points:

C#

GeoPoint p1 = new GeoPoint(10, 10);
GeoPoint p2 = new GeoPoint(30, 60);
mapControl.ZoomToRegion(p1, p2, 0.3);

VB.NET

Dim p1 As New GeoPoint(10, 10)
Dim p2 As New GeoPoint(30, 60)
map.ZoomToRegion(p1, p2, 0.3)

The code above uses the following classes and properties:

Class or Property	Description
MapControl.ZoomToRegion	Zooms a map to a rectangular region specified by its top-left and bottom-right points.
MapControl.ZoomToRegionBehavior	Specifies the Zoom to Region-related settings.
ZoomToRegionBehavior	The Zoom to Region behavior settings.