public void ProcessRequest(HttpContext context)
{
uint x, y, z;
//Parse request parameters
if (!uint.TryParse(context.Request.Params["x"], out x))
{
throw (new ArgumentException("Invalid parameter"));
}
if (!uint.TryParse(context.Request.Params["y"], out y))
{
throw (new ArgumentException("Invalid parameter"));
}
if (!uint.TryParse(context.Request.Params["z"], out z))
{
throw (new ArgumentException("Invalid parameter"));
}
// Create a bitmap of size 256x256
using (var bmp = new Bitmap(256, 256))
// get graphics from bitmap
using (var graphics = Graphics.FromImage(bmp))
{
// calc rect from tile key
var queryWindow = TransformTools.TileToWgs(x, y, z);
// build the sql
string sx1 = Convert.ToString(queryWindow.Left, CultureInfo.InvariantCulture);
string sy1 = Convert.ToString(queryWindow.Top, CultureInfo.InvariantCulture);
string sx2 = Convert.ToString(queryWindow.Right, CultureInfo.InvariantCulture);
string sy2 = Convert.ToString(queryWindow.Bottom, CultureInfo.InvariantCulture);
var strSql = string.Format("SELECT Id, AsBinary(Geometry) FROM WorldGeom WHERE MBRIntersects(Geometry, BuildMbr({0}, {1}, {2}, {3}));",
sx1, sy2, sx2, sy1);
using (SQLiteCommand command = new SQLiteCommand(strSql, Global.cn))
using (SQLiteDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
int id = reader.GetInt32(0);
byte[] wkb = reader[1] as byte[];
// create GDI path from wkb
var path = WkbToGdi.Parse(wkb, p => TransformTools.WgsToTile(x, y, z, p));
// fill polygon
var fill = new SolidBrush(Color.FromArgb(168, 0, 0, 255));
graphics.FillPath(fill, path);
fill.Dispose();
// draw outline
graphics.DrawPath(Pens.Black, path);
}
reader.Close();
}
//Stream the image to the client
using (var memoryStream = new System.IO.MemoryStream())
{
// Saving a PNG image requires a seekable stream, first save to memory stream
// http://forums.asp.net/p/975883/3646110.aspx#1291641
bmp.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Png);
var buffer = memoryStream.ToArray();
context.Response.ContentType = "image/png";
context.Response.OutputStream.Write(buffer, 0, buffer.Length);
}
}
}
public void ProcessRequest(HttpContext context)
{
uint x, y, z;
//Parse request parameters
if (!uint.TryParse(context.Request.Params["x"], out x))
{
throw (new ArgumentException("Invalid parameter"));
}
if (!uint.TryParse(context.Request.Params["y"], out y))
{
throw (new ArgumentException("Invalid parameter"));
}
if (!uint.TryParse(context.Request.Params["z"], out z))
{
throw (new ArgumentException("Invalid parameter"));
}
// Create a bitmap of size 256x256
using (var bmp = new Bitmap(256, 256))
// get graphics from bitmap
using (var graphics = Graphics.FromImage(bmp))
{
// calc rect from tile key
var queryWindow = TransformTools.TileToWgs(x, y, z);
// build the sql
var strSql = string.Format(CultureInfo.InvariantCulture,
@"SELECT WorldGeom.Id, AsBinary(Geometry), Pop/Area as PopDens FROM WorldGeom " +
@"JOIN WorldData on WorldData.Id = WorldGeom.Id " +
@"WHERE MBRIntersects(Geometry, BuildMbr({0}, {1}, {2}, {3}));",
queryWindow.Left, queryWindow.Top, queryWindow.Right, queryWindow.Bottom);
var choropleth = new Classification <double, Color>
{
MinValue = 0, // lower border for classification
DefaultAttribute = Color.White, // color if key hits no class
Values = new SortedList <double, Color> { // the classes
{ 50, Color.Green },
{ 100, Color.LightGreen },
{ 250, Color.Yellow },
{ 500, Color.Orange },
{ 1000, Color.Red },
{ 2500, Color.DarkRed },
{ double.MaxValue, Color.Purple }
}
};
using (SQLiteCommand command = new SQLiteCommand(strSql, Global.cn))
using (SQLiteDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
int id = reader.GetInt32(0);
byte[] wkb = reader[1] as byte[];
double popDens = reader.IsDBNull(2)? -1 : reader.GetDouble(2);
// create GDI path from wkb
var path = WkbToGdi.Parse(wkb, p => TransformTools.WgsToTile(x, y, z, p));
// fill polygon
var color = choropleth.GetValue(popDens);
var fill = new SolidBrush(Color.FromArgb(168, color.R, color.G, color.B));
graphics.FillPath(fill, path);
fill.Dispose();
// draw outline
graphics.DrawPath(Pens.Black, path);
}
reader.Close();
}
//Stream the image to the client
using (var memoryStream = new System.IO.MemoryStream())
{
// Saving a PNG image requires a seekable stream, first save to memory stream
// http://forums.asp.net/p/975883/3646110.aspx#1291641
bmp.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Png);
var buffer = memoryStream.ToArray();
context.Response.ContentType = "image/png";
context.Response.OutputStream.Write(buffer, 0, buffer.Length);
}
}
}