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Simplified LatLonBoxToMap

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ClemensFischer 2026-01-26 19:00:40 +01:00
parent 8685f0fea5
commit 1827372db6
1 changed files with 30 additions and 33 deletions
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63
MapControl/Shared/MapProjection.cs
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@ -100,9 +100,7 @@ namespace MapControl
}
}
protected virtual void CenterChanged()
{
}
protected virtual void CenterChanged() { }
/// <summary>
/// Gets the relative scale at the specified geographic coordinates.
@ -145,10 +143,10 @@ namespace MapControl
/// </summary>
public Rect? BoundingBoxToMap(BoundingBox boundingBox)
{
var southWest = LocationToMap(boundingBox.South, boundingBox.West);
var northEast = LocationToMap(boundingBox.North, boundingBox.East);
var sw = LocationToMap(boundingBox.South, boundingBox.West);
var ne = LocationToMap(boundingBox.North, boundingBox.East);
return southWest.HasValue && northEast.HasValue ? new Rect(southWest.Value, northEast.Value) : null;
return sw.HasValue && ne.HasValue ? new Rect(sw.Value, ne.Value) : null;
}
/// <summary>
@ -157,47 +155,46 @@ namespace MapControl
/// </summary>
public BoundingBox MapToBoundingBox(Rect rect)
{
var southWest = MapToLocation(rect.X, rect.Y);
var northEast = MapToLocation(rect.X + rect.Width, rect.Y + rect.Height);
var sw = MapToLocation(rect.X, rect.Y);
var ne = MapToLocation(rect.X + rect.Width, rect.Y + rect.Height);
return southWest != null && northEast != null ? new BoundingBox(southWest, northEast) : null;
return sw != null && ne != null ? new BoundingBox(sw, ne) : null;
}
/// <summary>
/// Transforms a LatLonBox in geographic coordinates to a rotated Rect in projected map coordinates.
/// Returns null when the LatLonBox can not be transformed.
/// Returns (null, 0d) when the LatLonBox can not be transformed.
/// </summary>
public (Rect?, double) LatLonBoxToMap(LatLonBox latLonBox)
{
Rect? rect = null;
var rotation = 0d;
var centerLatitude = (latLonBox.South + latLonBox.North) / 2d;
var centerLongitude = (latLonBox.West + latLonBox.East) / 2d;
Point? center, north, south, west, east;
var sw = LocationToMap(latLonBox.South, latLonBox.West);
var se = LocationToMap(latLonBox.South, latLonBox.East);
var nw = LocationToMap(latLonBox.North, latLonBox.West);
var ne = LocationToMap(latLonBox.North, latLonBox.East);
if ((center = LocationToMap(centerLatitude, centerLongitude)).HasValue &&
(north = LocationToMap(latLonBox.North, centerLongitude)).HasValue &&
(south = LocationToMap(latLonBox.South, centerLongitude)).HasValue &&
(west = LocationToMap(centerLatitude, latLonBox.West)).HasValue &&
(east = LocationToMap(centerLatitude, latLonBox.East)).HasValue)
if (sw.HasValue && se.HasValue && nw.HasValue && ne.HasValue)
{
var dx1 = east.Value.X - west.Value.X;
var dy1 = east.Value.Y - west.Value.Y;
var dx2 = north.Value.X - south.Value.X;
var dy2 = north.Value.Y - south.Value.Y;
var width = Math.Sqrt(dx1 * dx1 + dy1 * dy1);
var height = Math.Sqrt(dx2 * dx2 + dy2 * dy2);
var x = center.Value.X - width / 2d;
var y = center.Value.Y - height / 2d;
// Additional rotation caused by the projection, calculated as mean value
// of the two angles measured relative to the east and north axis.
//
var r1 = Math.Atan2(dy1, dx1) * 180d / Math.PI;
var r2 = Math.Atan2(-dx2, dy2) * 180d / Math.PI;
var south = new Point((sw.Value.X + se.Value.X) / 2d, (sw.Value.Y + se.Value.Y) / 2d); // south midpoint
var north = new Point((nw.Value.X + ne.Value.X) / 2d, (nw.Value.Y + ne.Value.Y) / 2d); // north midpoint
var west = new Point((nw.Value.X + sw.Value.X) / 2d, (nw.Value.Y + sw.Value.Y) / 2d); // west midpoint
var east = new Point((ne.Value.X + se.Value.X) / 2d, (ne.Value.Y + se.Value.Y) / 2d); // east midpoint
var center = new Point((west.X + east.X) / 2d, (west.Y + east.Y) / 2d); // midpoint of segment west-east
var dx1 = east.X - west.X;
var dy1 = east.Y - west.Y;
var dx2 = north.X - south.X;
var dy2 = north.Y - south.Y;
var width = Math.Sqrt(dx1 * dx1 + dy1 * dy1); // distance west-east
var height = Math.Sqrt(dx2 * dx2 + dy2 * dy2); // distance south-north
var x = center.X - width / 2d;
var y = center.Y - height / 2d;
rect = new Rect(x, y, width, height);
rotation = latLonBox.Rotation + (r1 + r2) / 2d % 360d;
// Additional rotation from the slope of the line segment west-east.
//
rotation = (latLonBox.Rotation + Math.Atan2(dy1, dx1) * 180d / Math.PI) % 360d;
}
return (rect, rotation);