<ResCategoryAttribute("Behavior")>
<NotifyParentPropertyAttribute(True)>
<DefaultValueAttribute()>
<ResDescriptionAttribute("The additional area to show on the Overview map when compared to the area shown on the associated Map control. The default is 500%. This property is ignored when StaticMode is true.")>
<PersistenceModeAttribute()>
Public Property ExpandPercentage As Double

Visual Basic (Usage)	Copy Code
Dim instance As OverviewMap Dim value As Double   instance.ExpandPercentage = value   value = instance.ExpandPercentage

[ResCategoryAttribute("Behavior")]
[NotifyParentPropertyAttribute(true)]
[DefaultValueAttribute()]
[ResDescriptionAttribute("The additional area to show on the Overview map when compared to the area shown on the associated Map control. The default is 500%. This property is ignored when StaticMode is true.")]
[PersistenceModeAttribute()]
public double ExpandPercentage {get; set;}

Return Value

The ExpandPercentage determines how much more map area that the overview map displays compared to the main map. The overview map multiplies the height and width of the Map by the ExpandPercentage and adds this distance to the main map's extent to determine its own extent. If the overview map has a different height/width proportion than the main map, the expanded extent is fit within the narrowest side, and the other dimension displays additional area.

Example: the main map's extent in degrees is xmin=10, xmax=20, ymin=20, ymax=30, with width=500 pixels and height=500 pixels. The overview map has width=150 pixels and height=100 pixels. The ExpandPercentage is 500 (the default). To calculate its extent, the overview map multiplies the main map's extent by 500 percent (5.0), and adds it to the main map's extent:



5.0 * 10 degrees + 10 degrees = 60 degrees



(same for height and width in this case). The center of the overview map is the same as the main map (x=15, y=25). The overview extent should then cover the area from xmin=-15, xmax=45, ymin=-5, ymax=55. However, since the overview map has different proportions from the main map, it will extend further in the x (width) dimension than these coordinates.

When the main map is at or near the full extent of the primary map resource, the overview map will only extend to the limits of the primary resource. In this case, the overview map expands the extent of the main map by less than the ExpandPercentage.

Reference