wyvern.kernel.player
Class ImageFetcher

java.lang.Object
  wyvern.kernel.player.ImageFetcher

All Implemented Interfaces:

BuiltInCommand, Command

public class ImageFetcher

extends java.lang.Object

implements BuiltInCommand

Handles requests for tile/image mappings, and for downloading missing or out-of-date images to the client.

Version:

1.0, Jul 26, 2000

Author:

Steve Yegge

Method Summary

void	addCommands(java.util.Map commands, CommandList list) Tells the Command to add the commands that it wants to implement into the passed data structure.
CommandEvent	createEvent(CommandEvent initialInfo) Creates a CommandEvent that encapsulates all the state necessary to perform the command.
boolean	execute(CommandEvent event) Executes the specified CommandEvent.
static ImageFetcher	getImpl()
boolean	knowsCommand(java.lang.String command) Returns true if this Command wants to handle the command.
boolean	requestImage(CommandEvent event) Client has asked to download a missing or out-of-date image.
boolean	requestTileNumber(CommandEvent event) Client has asked which image corresponds to the specified tile number.

Methods inherited from class java.lang.Object

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

Method Detail

getImpl

public static ImageFetcher getImpl()

addCommands

public final void addCommands(java.util.Map commands,
                              CommandList list)

Description copied from interface: BuiltInCommand

Tells the Command to add the commands that it wants to implement into the passed data structure.

Specified by:

addCommands in interface BuiltInCommand

Parameters:

commands - a Map whose keys are commands, and whose values are Commands that handle those commands.

list - the CommandList the Command is being added to.

knowsCommand

public final boolean knowsCommand(java.lang.String command)

Description copied from interface: Command

Returns true if this Command wants to handle the command. The Command can examine the arguments and determine that it doesn't actually understand the command, in which case it should return false.

This method exists to allow more than one game object to implement the same command verb, but with different expected arguments.

If two objects register for the same command and the same arguments, the object that was registered most recently gets to handle at the command.

Specified by:

knowsCommand in interface Command

Parameters:

command - the entire command string, including arguments

Returns:

true if we want to handle the command

createEvent

public final CommandEvent createEvent(CommandEvent initialInfo)

Description copied from interface: Command

Creates a CommandEvent that encapsulates all the state necessary to perform the command. A well-designed CommandEvent exposes all of its "properties" so that hook objects can modify its behavior. For instance, many commands result in some sort of message being sent back to the client. The message should be among the properties that hooks can override.

This method is called by the kernel. The kernel passes the event to the pre-hook, then calls Command.execute() (below) to execute the event, and finally calls the post-hook.

Specified by:

createEvent in interface Command

Parameters:

initialInfo - a "blank" CommandEvent containing only the command text and the agent who's performing the command. This initial event is created by the originator of the event (e.g. the AI or player's command preprocessor).

Returns:

a CommandEvent subclass encapsulating this command's execution parameters and state. It should copy in the fields from the passed-in event.

execute

public final boolean execute(CommandEvent event)

Description copied from interface: Command

Executes the specified CommandEvent. The CommandEvent contains all the parameters and state required to execute the command; the parameters have been filtered through hook objects, so they may not be the same as when the event was created.

Specified by:

execute in interface Command

Parameters:

event - the CommandEvent to execute

Returns:

true if the event completed successfully, else false.

requestTileNumber

public final boolean requestTileNumber(CommandEvent event)

Client has asked which image corresponds to the specified tile number.

requestImage

public final boolean requestImage(CommandEvent event)

Client has asked to download a missing or out-of-date image.