/// <summary>
/// Converts a LineString in world coordinates to a Skia path
/// </summary>
/// <param name="coordinates">List of points in Mapsui world coordinates</param>
/// <param name="viewport">Viewport implementation</param>
/// <param name="clipRect">Rectangle to clip to. All lines outside aren't drawn.</param>
/// <returns></returns>
public static SKPath ToSkiaPath(this LineString lineString, IReadOnlyViewport viewport, SKRect clipRect)
{
var coordinates = lineString.Coordinates;
// First convert List<Points> to screen coordinates
var vertices = ClippingFunctions.WorldToScreen(viewport, coordinates);
var path = new SKPath();
var lastPoint = SKPoint.Empty;
for (var i = 1; i < vertices.Count; i++)
{
// Check each part of LineString, if it is inside or intersects the clipping rectangle
var intersect = ClippingFunctions.LiangBarskyClip(vertices[i - 1], vertices[i], clipRect, out var intersectionPoint1, out var intersectionPoint2);
if (intersect != ClippingFunctions.Intersection.CompleteOutside)
{
// If the last point isn't the same as actual starting point ...
if (lastPoint.IsEmpty || !lastPoint.Equals(intersectionPoint1))
{
// ... than move to this point
path.MoveTo(intersectionPoint1);
}
// Draw line
path.LineTo(intersectionPoint2);
// Save last end point for later use
lastPoint = intersectionPoint2;
}
}
return(path);
}
