How to zoom to fit in WP7 Bing Maps control using LocationCollection?
How can I zoom the Microsoft.Phone.Controls.Maps.Map control to the correct zoom level on Windows Phone 7?
I have a LocationCollection of GeoCoordinates and I calculated the Center myself, but now how do I calculate the correct zoom level to fit the LocationCollection?
P.S. Is there an out of the box method to calculate the center of GeoCoordinates so I don't have to calculate it myself?
EDIT: I've开发者_开发问答 found another fine solution: http://4mkmobile.com/2010/09/quick-tip-position-a-map-based-on-a-collection-of-pushpins/
map.SetView(LocationRect.CreateLocationRect(points));
You can use the following code to calculate the LocationRect
that bounds a set of points, and then pass the LocationRect
to the SetView()
method on the map control:
var bounds = new LocationRect(
points.Max((p) => p.Latitude),
points.Min((p) => p.Longitude),
points.Min((p) => p.Latitude),
points.Max((p) => p.Longitude));
map.SetView(bounds);
The map control handles animating from the current position to the new location.
NOTE: You'll need a using
statement for System.Linq
to get the Min
and Max
methods.
Derek has already given the answer so you should accept his, I offer an alternative code for cases where there many points. This approach only iterates the points collection once instead 4 times however it isn't as asthetically pleasing.
double north, west, south, west;
north = south = points[0].Latitude;
west = east = points[0].Longitude;
foreach (var p in points.Skip(1))
{
if (north < p.Latitude) north = p.Latitude;
if (west > p.Longitude) west = p.Longitude;
if (south > p.Latitude) south = p.Latitude;
if (east < p.Longitude) east = p.Longitude
}
map.SetView(new LocationRect(north, west, south, east));
As suggested by the other answers I use SetView
with a LocationRect
.
However I found that it always produces to low zoom level, since only integer values was used. If for instance the perfect zoom level would be 5.5, you would get 5.0. To get a proper fit I calculate a new zoom level from TargetZoomLevel
and TargetBoundingRectangle
:
viewRect = LocationRect.CreateLocationRect(coordinates);
map.SetView(viewRect);
double scale = map.TargetBoundingRectangle.Height/viewRect.Height;
map.ZoomLevel = map.TargetZoomLevel + Math.Log(scale, 2);
This example sets the zoom level to fit viewRect
's height on the screen.
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