public void Test1()
{
var meters = WebMercatorHandler.LatLonToMeters(50, 4);
var pixels0 = WebMercatorHandler.MetersToPixels(meters, 0, 1024);
var pixels1 = WebMercatorHandler.MetersToPixels(meters, 1, 1024);
var pixels2 = WebMercatorHandler.MetersToPixels(meters, 2, 1024);
var pixels3 = WebMercatorHandler.MetersToPixels(meters, 3, 1024);
}
/// <summary>
/// Initializes this transformation utility
/// </summary>
/// <param name="tile">The tile's bounds</param>
/// <param name="extent">The tile's extent in pixel. Tiles are always square.</param>
public TileGeometryTransform(Tiles.Tile tile, uint extent) : this()
{
_tile = tile;
_extent = extent;
var meters = WebMercatorHandler.LatLonToMeters(_tile.Top, _tile.Left);
var pixels = WebMercatorHandler.MetersToPixels(meters, tile.Zoom, (int)extent);
_top = (long)pixels.y;
_left = (long)pixels.x;
}
/// <summary>
/// Checks to see if a geometries envelope is greater than 1 square pixel in size for a specified zoom leve.
/// </summary>
/// <param name="polygon">Polygon to test.</param>
/// <param name="zoom">Zoom level </param>
/// <returns></returns>
private static bool IsGreaterThanOnePixelOfTile(Geometry polygon, int zoom)
{
(double x1, double y1) = WebMercatorHandler.MetersToPixels(WebMercatorHandler.LatLonToMeters(polygon.EnvelopeInternal.MinY, polygon.EnvelopeInternal.MinX), zoom, 512);
(double x2, double y2) = WebMercatorHandler.MetersToPixels(WebMercatorHandler.LatLonToMeters(polygon.EnvelopeInternal.MaxY, polygon.EnvelopeInternal.MaxX), zoom, 512);
var dx = Math.Abs(x2 - x1);
var dy = Math.Abs(y2 - y1);
//Both must be greater than 0, and atleast one of them needs to be larger than 1.
return(dx > 0 && dy > 0 && (dx > 1 || dy > 1));
}
/// <summary>
/// Transforms the coordinate at <paramref name="index"/> of <paramref name="sequence"/> to the tile coordinate system.
/// The return value is the position relative to the local point at (<paramref name="currentX"/>, <paramref name="currentY"/>).
/// </summary>
/// <param name="sequence">The input sequence</param>
/// <param name="index">The index of the coordinate to transform</param>
/// <param name="currentX">The current horizontal component of the cursor location. This value is updated.</param>
/// <param name="currentY">The current vertical component of the cursor location. This value is updated.</param>
/// <returns>The position relative to the local point at (<paramref name="currentX"/>, <paramref name="currentY"/>).</returns>
public (int x, int y) Transform(CoordinateSequence sequence, int index, ref int currentX, ref int currentY)
{
var lon = sequence.GetOrdinate(index, Ordinate.X);
var lat = sequence.GetOrdinate(index, Ordinate.Y);
var meters = WebMercatorHandler.LatLonToMeters(lat, lon);
var pixels = WebMercatorHandler.MetersToPixels(meters, _tile.Zoom, (int)_extent);
int localX = (int)(pixels.x - _left);
int localY = (int)(_top - pixels.y);
int dx = localX - currentX;
int dy = localY - currentY;
currentX = localX;
currentY = localY;
return(dx, dy);
}
