kml_generator.rb

#!/usr/local/bin/ruby
require "pp"
require "cgi"
require "rubygems"
require "xmlsimple"
require 'yaml'



##
# Serves up kml..
class KMLHandler < RackWelder
  
  #set stuff up, log=logger, cfg=shiv kml config.
  def initialize ( log,http_conf, set)
    @logger = log
    
    #the ip of the requesting host..
    @REMOTE_IP_TAG="HTTP_X_FORWARDED_FOR"
    
    #save the config..
    @cfg = {
      "set" => set,
      "source" =>  "http://" +  http_conf["host"] + http_conf["base"] +"/" +set + "/bbox/%.20f/%.20f/%.20f/%.20f/",
      "url" => "http://" + http_conf["host"] + http_conf["base"]+"/" + "%s/kml/%.20f/%.20f/%.20f/%.20f/"
      }
    #save the root url.
  end
  
  
  # Do something..
  def process(request, response)
    begin
      @logger.puts("KML -> #{request.params[@REMOTE_IP_TAG]} -> #{request.params["REQUEST_URI"]}")
     
      uri = request.env["PATH_INFO"]
      if ( uri == nil)
        give404(response, "Try a real url, thats not nil.")
        return
      else
        #uri should be for the form something/set/kml/lt_x/tl_y/br_x/br_y
        uri = uri.split("/")
        
        if ( uri.length <= 6 )
          give404(response, "Try a real url, perhaps one that is valid and of the form /set/lt_x/tl_y/br_x/br_y")
          return
        end
        
        1.upto(6) {|x| puts "#{x*(-1)} #{uri[x*(-1)]}"}
        
        set = uri[-6]
        tl_x = uri[-4].to_f
        tl_y = uri[-3].to_f
        br_x = uri[-2].to_f
        br_y = uri[-1].to_f
        
        if (set != @cfg["set"])
          give404(response, "Try a real url, perhaps one that is valid and of the form /set/lt_x/tl_y/br_x/br_y where set is \"#{@cfg["set"]}\" not \"#{set}\"")
          return
        end
        
        ##
        # This is the case if things are really broken - possibly not possible now..
        # Not sure if the behavior is good, or bad -  should possibly just generate an error now..
        if ( br_x == nil || br_y == nil || tl_x == nil|| tl_y == nil||set==nil)
          give404(response, "Try a real url, perhaps one that is valid and of the form /set/kml/lt_x/tl_y/br_x/br_y")
          return
        end
        
        response.status = 200
        response.header["Content-Type"] = "application/vnd.google-earth.kml+xml"
        @logger.msgdebug("KMLHandler:process:"+ sprintf("(%g,%g) -> (%g,%g)", br_x.to_f, br_y.to_f, tl_x.to_f , tl_y.to_f))
        stuff = do_level(@cfg,set,tl_x.to_f, tl_y.to_f, br_x.to_f, br_y.to_f)
        response.write(stuff)
      end
    rescue => excpt
      ###
      # Ok, something very bad happend here... what to do..
      stuff = "Broken at #{Time.now.to_s}"
      stuff += "--------------------------\n"
      stuff += excpt.to_s + "\n"
      stuff += "--------------------------\n"
      stuff += excpt.backtrace.join("\n")
      stuff += "--------------------------\n"
      stuff += "request => " + YAML.dump(request)+ "\n-------\n"
      puts stuff
      Mailer.deliver_message(@cfg["mailer_config"], @cfg["mailer_config"]["to"], "shiv crash..", [stuff])
      @logger.logerr("Crash in::#{@lt}" + stuff)
    end
  end
  
  
  #generates a url to the new down level 
  def url_to_lower_level(hcfg,set,tl_x, tl_y, br_x, br_y)
    @logger.msgdebug("KMLHandler:url_to_lower_level:"+sprintf("url_to_lower_level(%g,%g) -> (%g,%g)", br_x.to_f, br_y.to_f, tl_x.to_f , tl_y.to_f) )
    return sprintf(hcfg["url"],set,tl_x, tl_y, br_x, br_y)
  end

  #url to actual image..
  def url_to_img(hcfg,set,tl_x, tl_y, br_x, br_y)
    @logger.msgdebug("KMLHandler:url_to_img:"+ sprintf("url_to_lower_level(%g,%g) -> (%g,%g)", br_x.to_f, br_y.to_f, tl_x.to_f , tl_y.to_f) )
    return sprintf(hcfg["source"],tl_x, br_y, br_x, tl_y) + ".png"
  end
  
  
  # Generates a bounding box google kml style
  
  def hshtoLatLonAltBox ( cfg,set,tl_x, tl_y, br_x, br_y , note)
    maxlodpixels = -1
    @logger.msgdebug("KMLHandler:hshtoLatLonAltBox:" + sprintf("((br_x - tl_x))=>%g (%s)",(br_x - tl_x), note ))
    
    #Old Lod
    #  "Lod"=>[ {"maxLodPixels"=>["#{maxlodpixels}"], "minLodPixels"=>["128"],  "minFadeExtent"=>["128"],  "maxFadeExtent"=>["128"]}],
    return {
         "name"=>[sprintf("%s_%.20f_%.20f_%.20f_%.20f%", set,tl_x, tl_y, br_x, br_y) ],
        "Region"=>
          [
            {
              "Lod"=>[ {"maxLodPixels"=>["#{maxlodpixels}"], "minLodPixels"=>["124"]}],
              "LatLonAltBox"=>
                [{
                  "east"=>["#{br_x}"],
                  "south"=>["#{br_y}"],
                  "west"=>["#{tl_x}"],
                  "north"=>["#{tl_y}"]
                }]
            }
          ],
        "Link"=>
          [{
            "href"=>[url_to_lower_level(cfg,set,tl_x, tl_y, br_x, br_y)],
            "viewRefreshMode"=>["onRegion"]
          }]
    } 
  end
  
  
  #generates a kml file for tl,br
  def do_level (cfg,set,tl_x, tl_y, br_x, br_y)
    
    w = br_x -  tl_x
    h = tl_y -  br_y
    w = w / 2.0
    h = h / 2.0
    
    maxlodpixels = 1024
    #maxlodpixels = 680
    #maxlodpixels = -1 if ((  br_x - tl_x   > 5 ))
    
    networklink = []
    
    ##
    # Zoom level 24 is the limit...
    
    if ( w > 360.0/(2**20))
        0.upto(1) do |x|
          0.upto(1) do |y|
              networklink += [hshtoLatLonAltBox(cfg,set,tl_x+w*x,     br_y+h*(y+1),    tl_x+w*(x+1),     br_y+h*(y),    "tl")]
          end
      end
     end
 
#Draw order stuff..
# "drawOrder"=>["#{((1.0/w)*180).to_i}"]
    hsh = {"Document"=>
  	[
            {
                "name"=>[sprintf("%s_%.20f_%.20f_%.20f_%.20f%d", set,tl_x, tl_y, br_x, br_y, rand(32000)) ],
                "NetworkLink"=> networklink,
    		"GroundOverlay"=>
                    [
                        {
                            "LatLonBox"=>
                            [
                                {
                                    "east"=>["#{br_x}"],
                                    "south"=>["#{br_y}"],
                                    "west"=>["#{tl_x}"],
                                    "north"=>["#{tl_y}"]
				}
                            ],
                            "Icon"=>[
                                        {
                                                "href"=>["#{url_to_img(cfg,set,tl_x, tl_y, br_x, br_y)}"]
                                        }
                                    ],
                            "drawOrder"=>["#{((1.0/w)*180 + 1000).to_i}"]
			}
		    ],
                "Region"=>
     		    [
                        {
                            "Lod"=>[ {"maxLodPixels"=>["#{maxlodpixels}"], "minLodPixels"=>["124"]}],
                            "LatLonAltBox"=>
                                [{
                                    "east"=>["#{br_x}"],
                                    "south"=>["#{br_y}"],
                                    "west"=>["#{tl_x}"],
                                    "north"=>["#{tl_y}"]
                                }]
                        }
                    ]
            }
	],
 	"xmlns"=>"http://earth.google.com/kml/2.1"
    }


    return (XmlSimple.xml_out(hsh,  { "rootname" => 'kml'})  )
  end
end