/// <summary>
/// Creates a Bitmap image with size width,height.
/// From the area (x1,y2) to (x2,y2) where x1,y1,x2,y2 are
/// geological coordinates.
/// </summary>
public Bitmap GetTile(double x1, double y1, double x2, double y2, int width, int height)
{
Bitmap tile = new Bitmap(width, height);
int zoomLevel = GetZoomLevel(x1, x2, width);
BBox box = new BBox(x1, y1, x2, y2);
// Make searchbox wider dependent on zoomlevel.
// Explanation at summary of getSearchBBox.
BBox searchBox = getSearchBBox(box, zoomLevel);
// Clears image with grey backgroundcolor.
Graphics.FromImage(tile).Clear(Color.FromArgb(230, 230, 230));
// Draww all seperate elements in following order:
// Land -> Buildings -> Streets -> extra locations (Busstations, parking signs)
drawLandCurves(box, tile, graph.GetLandsInBBox(searchBox));
drawBuildingCurves(box, tile, graph.GetBuildingsInBBox(searchBox));
drawStreetCurves(box, tile, graph.GetWaysInBBox(searchBox), zoomLevel);
drawExtras(box, tile, graph.GetExtrasInBBox(BBox.getResizedBBox(box, 2)), zoomLevel);
//drawAdditionalCurves(box, tile, graph.GetExtrasinBBOX(searchBox), zoomLevel);
//used for debugging
//Graphics.FromImage(tile).DrawLines(Pens.LightGray, new Point[] { Point.Empty, new Point(0, height), new Point(width, height), new Point(width, 0), Point.Empty });
return(tile);
}
/// <summary>
/// Resizes the BBox box if zoomlevel is very low.
/// This is because when curves pass through a tile but no nodes
/// of that curve are in that tile the curve won't be drawn in that tile.
/// So on very low zoomlevels, we need to search wider to draw all
/// curves in a tile.
/// </summary>
private BBox getSearchBBox(BBox box, int zoomLevel)
{
if (zoomLevel == 1)
{
return(BBox.getResizedBBox(box, 3));
}
if (zoomLevel == 0)
{
return(BBox.getResizedBBox(box, 7));
}
return(box);
}