private Matrix <double> GetPictureDrawMatrix(SKPicture picture, Position gpsPosition, Size pixelSize)
{
Size platformPixelsSize = pixelSize * PlatformPixelScale;
Matrix <double> matrix = Matrix <double> .Build.DenseIdentity(3, 3);
Point mercatorPosition = gpsPosition.ToMercator();
SKRect sourceRect = picture.CullRect;
SKMapSpan drawSpan = PixelsToMapSpanAtScale(platformPixelsSize, gpsPosition, _ScaleFactor);
double xScale = platformPixelsSize.Width / sourceRect.Width;
double yScale = platformPixelsSize.Height / sourceRect.Height;
SKPoint canvasPoint;
if (drawSpan.Crosses180thMeridianRight() && _MercatorRenderArea.Left < SKMapExtensions.MercatorCenterOffset)
{
// We cross the 180th meridian to the right and are drawing to a tile on the left side of the map, so wrap around
mercatorPosition.X -= SKMapExtensions.MercatorMapSize;
}
if (drawSpan.Crosses180thMeridianLeft() && _MercatorRenderArea.Right > SKMapExtensions.MercatorCenterOffset)
{
// We cross the 180th meridian to the right and are drawing to a tile on the left side of the map, so wrap around
mercatorPosition.X += SKMapExtensions.MercatorMapSize;
}
canvasPoint = ApplyMatrix(mercatorPosition);
matrix *= Matrix <double> .Build.Translation(canvasPoint.X, canvasPoint.Y);
matrix *= Matrix <double> .Build.Scale(xScale, yScale);
matrix *= Matrix <double> .Build.Translation(sourceRect.Width * -0.5, sourceRect.Height * -0.5);
return(matrix);
}
public static bool Crosses180thMeridian(this SKMapSpan self)
{
return(self.Crosses180thMeridianRight() ||
self.Crosses180thMeridianLeft());
}