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MapProjection.GridConvergence, rotation instead of Matrix

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ClemensFischer 2026-01-29 21:36:11 +01:00
parent 45b47bbae4
commit 4ad9f2ea2a
15 changed files with 272 additions and 239 deletions
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46
MapControl/Shared/MapProjection.cs
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@ -57,10 +57,17 @@ namespace MapControl
/// <summary>
/// Gets the relative transform at the specified geographic coordinates.
/// The returned Matrix represents the local distortion of the map projection.
/// The returned Matrix represents the local relative scale and rotation.
/// </summary>
public abstract Matrix RelativeTransform(double latitude, double longitude);
/// <summary>
/// Gets the grid convergence angle in degrees at the specified projected map coordinates.
/// Used for rotating the Rect resulting from BoundingBoxToMap in non-normal-cylindrical
/// projections, i.e. Transverse Mercator and Polar Stereographic.
/// </summary>
public virtual double GridConvergence(double x, double y) => 0d;
/// <summary>
/// Transforms geographic coordinates to a Point in projected map coordinates.
/// </summary>
@ -88,33 +95,42 @@ namespace MapControl
/// <summary>
/// Transforms a BoundingBox in geographic coordinates to a Rect in projected map coordinates
/// with an optional transform Matrix.
/// with an optional rotation angle in degrees.
/// </summary>
public (Rect, Matrix?) BoundingBoxToMap(BoundingBox boundingBox)
public (Rect, double) BoundingBoxToMap(BoundingBox boundingBox)
{
Rect rect;
Matrix? transform = null;
var rotation = 0d;
var southWest = LocationToMap(boundingBox.South, boundingBox.West);
var northEast = LocationToMap(boundingBox.North, boundingBox.East);
if (IsNormalCylindrical)
{
var southWest = LocationToMap(boundingBox.South, boundingBox.West);
var northEast = LocationToMap(boundingBox.North, boundingBox.East);
rect = new Rect(southWest.X, southWest.Y, northEast.X - southWest.X, northEast.Y - southWest.Y);
}
else
{
var latitude = (boundingBox.South + boundingBox.North) / 2d;
var longitude = (boundingBox.West + boundingBox.East) / 2d;
var center = LocationToMap(latitude, longitude);
var width = MeterPerDegree * (boundingBox.East - boundingBox.West) * Math.Cos(latitude * Math.PI / 180d);
var height = MeterPerDegree * (boundingBox.North - boundingBox.South);
var southEast = LocationToMap(boundingBox.South, boundingBox.East);
var northWest = LocationToMap(boundingBox.North, boundingBox.West);
var south = new Point((southWest.X + southEast.X) / 2d, (southWest.Y + southEast.Y) / 2d);
var north = new Point((northWest.X + northEast.X) / 2d, (northWest.Y + northEast.Y) / 2d);
var centerX = (south.X + north.X) / 2d;
var centerY = (south.Y + north.Y) / 2d;
var dx = north.X - south.X;
var dy = north.Y - south.Y;
var dxS = southEast.X - southWest.X;
var dyS = southEast.Y - southWest.Y;
var dxN = northEast.X - northWest.X;
var dyN = northEast.Y - northWest.Y;
var width = (Math.Sqrt(dxS * dxS + dyS * dyS) + Math.Sqrt(dxN * dxN + dyN * dyN)) / 2d;
var height = Math.Sqrt(dx * dx + dy * dy);
rect = new Rect(center.X - width / 2d, center.Y - height / 2d, width, height);
transform = RelativeTransform(latitude, longitude);
rect = new Rect(centerX - width / 2d, centerY - height / 2d, width, height);
rotation = -GridConvergence(centerX, centerY); // invert direction for RotateTransform
}
return (rect, transform);
return (rect, rotation);
}
/// <summary>