Class Rasterer

java.lang.Object

Rasterer

public class Rasterer
extends java.lang.Object

This class provides all code necessary to take a query box and produce a query result. The getMapRaster method must return a Map containing all seven of the required fields, otherwise the front end code will probably not draw the output correctly.

Constructor Summary

Constructors

Constructor and Description
Rasterer(java.lang.String imgRoot) imgRoot is the name of the directory containing the images.

Method Summary

Modifier and Type	Method and Description
java.util.Map<java.lang.String,java.lang.Object>	getMapRaster(java.util.Map<java.lang.String,java.lang.Double> params) Takes a user query and finds the grid of images that best matches the query.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Rasterer

public Rasterer(java.lang.String imgRoot)

imgRoot is the name of the directory containing the images. You may not actually need this for your class.

Method Detail

getMapRaster

public java.util.Map<java.lang.String,java.lang.Object> getMapRaster(java.util.Map<java.lang.String,java.lang.Double> params)

Takes a user query and finds the grid of images that best matches the query. These images will be combined into one big image (rastered) by the front end.

The grid of images must obey the following properties, where image in the grid is referred to as a "tile".

• Has dimensions of at least w by h, where w and h are the user viewport width and height.
• The tiles collected must cover the most longitudinal distance per pixel (LonDPP) possible, while still covering less than or equal to the amount of longitudinal distance per pixel in the query box for the user viewport size.
• Contains all tiles that intersect the query bounding box that fulfill the above condition.
• The tiles must be arranged in-order to reconstruct the full image.

Parameters:

params - Map of the HTTP GET request's query parameters - the query box and the user viewport width and height.

Returns:

A map of results for the front end as specified: "render_grid" : String[][], the files to display "raster_ul_lon" : Number, the bounding upper left longitude of the rastered image
"raster_ul_lat" : Number, the bounding upper left latitude of the rastered image
"raster_lr_lon" : Number, the bounding lower right longitude of the rastered image
"raster_lr_lat" : Number, the bounding lower right latitude of the rastered image
"depth" : Number, the 1-indexed quadtree depth of the nodes of the rastered image. Can also be interpreted as the length of the numbers in the image string.
"query_success" : Boolean, whether the query was able to successfully complete. Don't forget to set this to true!

See Also:

MapServer.REQUIRED_RASTER_REQUEST_PARAMS