public void displayCallout(IMapAnnotation annotation, IAnnotationMarker annotationElement)
{
// Hide any existing callout
hideCallout();
// There is only ever one callout
MapCallout callout = new MapCallout();
calloutLayer.Children.Add(callout);
// Hook up tap event
callout.Callout_Tapped += callout_Callout_Tapped;
// Assign this annotation as the data context of the callout - so it can get Title, Subtitle, etc
callout.DataContext = annotation;
// Position
MapLayer.SetPosition(callout, new Location(annotation.Latitude, annotation.Longitude));
// Callout anchor point also depends upon the anchor of the pushpin
MapLayer.SetPositionAnchor(callout, new Windows.Foundation.Point(
CALLOUT_ANCHOR_X + annotationElement.PositionAnchor.X,
CALLOUT_ANCHOR_Y + annotationElement.PositionAnchor.Y));
// Appear
callout.animateOnscreen();
Point offsetRequired;
if (!isCalloutInView(callout, out offsetRequired))
map.scrollBy(offsetRequired);
// Store for later
lastCallout = callout;
}
// Helpers
bool isCalloutInView(MapCallout callout, out Point offsetRequired)
{
offsetRequired = new Point();
Location calloutLocation = MapLayer.GetPosition(callout);
Point calloutTranslation = MapLayer.GetPositionAnchor(callout);
Point calloutPixelLocation;
if (!map.TryLocationToPixel(calloutLocation, out calloutPixelLocation))
throw new Exception("Cannot get location of callout ");
// Where is the callout?
Point calloutTopLeftLocation = new Point(calloutPixelLocation.X - calloutTranslation.X, calloutPixelLocation.Y - calloutTranslation.Y);
Rect calloutRect = new Rect(calloutTopLeftLocation, new Size(MapConstants.CalloutWidth, MapConstants.CalloutHeight));
// Work out if it is within the map boundary
double offsetXRequired = 0;
double offsetYRequired = 0;
double mapWidth = map.ActualWidth;
double mapHeight = map.ActualHeight;
if (calloutRect.Left < 0)
offsetXRequired = (0 - calloutRect.Left);
else if (calloutRect.Right > mapWidth)
offsetXRequired = (mapWidth - calloutRect.Right);
if (calloutRect.Top < 0)
offsetYRequired = (0 - calloutRect.Top);
else if (calloutRect.Bottom > mapHeight)
offsetYRequired = (mapHeight - calloutRect.Bottom);
offsetRequired = new Point(offsetXRequired, offsetYRequired);
return (offsetXRequired == 0) && (offsetYRequired == 0);
}
public void hideCallout()
{
if (lastCallout == null) return;
// Unhook tapped event
lastCallout.Callout_Tapped -= callout_Callout_Tapped;
// Animate disappearance
lastCallout.Callout_Disappeared += lastCallout_Callout_Disappeared;
lastCallout.animateOffscreen();
lastCallout = null;
}
