wyvern.kernel.player
Class GroundCamera

java.lang.Object
  wyvern.kernel.maps.AbstractCamera
      wyvern.kernel.player.GroundCamera

All Implemented Interfaces:

Camera, RPCDataSource

public class GroundCamera

extends AbstractCamera

This class implements a camera that views the ground beneath the player, to update the ground-display on the client.

Ground-cameras are pretty simple beasts. They're only interested in what's under the player. They show everything, in the order the objects appear in the map cell. Whenever the player moves, the camera is completely invalidated. The only tricky thing the ground camera does is to examine the lists of objects being sent, and see if exactly one entry is being added, removed, or modified. If so, it sends a RemoteInventory command to add, remove or modify the index in question. This results in a big speedup for handheld clients.

Version:

1.0, Mar 28, 1998

Author:

Steve Yegge

Field Summary

protected java.util.List

lastFrame_

Fields inherited from class wyvern.kernel.maps.AbstractCamera

bounds_, client_, completelyInvalid_, frame_, hasMoved_, height_, left_, map_, player_, ready_, size_, top_, width_, xoffset_, yoffset_

Constructor Summary

GroundCamera(RemoteClient client, Player player)
Constructs a new GroundCamera for the specified player.

Method Summary

protected void	add(GroundFrame frame, int index) Adds an item from the new frame at the specified index.
boolean	changesNotVisible(MapDirtyRegions changes) Returns true if none of the map changes were visible to us.
void	clearLastFrame() Nulls out the lastFrame_ field, which forces the next refresh request to go through, even if the contents haven't changed.
protected int	examineChanges(GroundFrame frame) Figures out what's changed since the last frame.
java.util.List	getLastFrame() Returns the list of objects that were last sent to the client.
DisplayPolicy	makeFrame() Creates an AbstractFrame subclass to use as our DisplayPolicy.
protected void	modify(GroundFrame frame, int index) Modifies an item in place.
void	move(int xoffset, int yoffset) Makes sure the GroundCamera is invalidated when it moves.
protected void	resendAll(GroundFrame frame) Resends the entire new frame to the client.
void	sendEmptyList() Sends a blank screen.
boolean	sendInfo(GroundFrame frame) Sends the information gathered by the GroundViewer to the client.
void	setMap(GameMap map, int x, int y) Sets the map for the camera.
void	setShowingSpells(boolean show) Turns the display of spells on or off in the Ground View.
void	setViewRect(Rectangle r) Resets the view rectangle; dumps the saved-object list.
void	setViewSize(int w, int h) Changes the view size; dumps the saved-object list.
boolean	showingSpells() Returns true if we're displaying spells in the ground view.
protected int	tryAdd(java.util.List objects, GroundFrame frame) The new list has one more item than the previous list.
protected int	tryModify(java.util.List objects, GroundFrame frame) Looks to see if exactly one item was modified since the last send.
protected int	tryRemove(java.util.List objects, GroundFrame frame) The new list has one less item than the previous list.
boolean	updateClient(DisplayPolicy frame) Sends the current set of map changes to the client.
boolean	updateGroundDisplay(GroundFrame frame) Shows what's beneath the player.
void	validate(MapDirtyRegions changes) CameraManager tells camera to update itself.

Methods inherited from class wyvern.kernel.maps.AbstractCamera

forceInvalidate, getCenter, getFrame, getMap, getOwner, getPosition, getViewRect, getViewSize, hasBeenMoved, invalidate, invalidateNoRayCast, isHandheld, isInvalid, isShutDown, markReady, markValid, moveFrame, setHandheld, setMap, setMoved, setPosition, shutDown, toString, tryUpdate

Methods inherited from class java.lang.Object

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

Field Detail

lastFrame_

protected java.util.List lastFrame_

Constructor Detail

GroundCamera

public GroundCamera(RemoteClient client,
                    Player player)
             throws java.lang.Exception

Constructs a new GroundCamera for the specified player.

Method Detail

validate

public void validate(MapDirtyRegions changes)

CameraManager tells camera to update itself.

Specified by:

validate in interface Camera

Overrides:

validate in class AbstractCamera

changesNotVisible

public boolean changesNotVisible(MapDirtyRegions changes)

Returns true if none of the map changes were visible to us.

updateClient

public boolean updateClient(DisplayPolicy frame)

Sends the current set of map changes to the client.

Specified by:

updateClient in class AbstractCamera

Parameters:

frame - the frame to gather the data

Returns:

true if any data was sent. It's essential that subclasses set this flag correctly for the camera to work properly. If the subclass determines that nothing has changed within the view of the camera, and doesn't make any calls to the RemoteClient as a result, then it should return false.

makeFrame

public DisplayPolicy makeFrame()

Creates an AbstractFrame subclass to use as our DisplayPolicy.

Returns:

the frame implementation we want to use

updateGroundDisplay

public boolean updateGroundDisplay(GroundFrame frame)
                            throws java.lang.Exception

Shows what's beneath the player. Called by updateClient().

Parameters:

frame - the frame this camera has opted to use

Returns:

true if any data was sent

Throws:

java.lang.Exception

sendInfo

public boolean sendInfo(GroundFrame frame)
                 throws java.lang.Exception

Sends the information gathered by the GroundViewer to the client.

Parameters:

frame - the frame we're using

Returns:

true if we actually sent any data

Throws:

java.lang.Exception

resendAll

protected void resendAll(GroundFrame frame)
                  throws java.lang.Exception

Resends the entire new frame to the client.

Parameters:

frame - the new frame

Throws:

java.lang.Exception

examineChanges

protected int examineChanges(GroundFrame frame)
                      throws java.lang.Exception

Figures out what's changed since the last frame. If nothing has changed, we return NO_CHANGE , and don't resend anything. If more than one item has changed, we return RESEND_ALL and resend the whole frame.

If exactly one item has changed, we just resend that one, and we do it from this method (actually from a helper that knows how to add, remove, or modify an item in the list). This situation happens whenever someone drops something or picks it up, so it greatly increases the refresh speed for buying, selling, repairing, and so on, particularly on handheld devices.

Parameters:

frame - the GroundFrame to send

Returns:

NO_CHANGE, RESEND_ALL, or MODIFY

Throws:

java.lang.Exception

tryModify

protected int tryModify(java.util.List objects,
                        GroundFrame frame)
                 throws java.lang.Exception

Looks to see if exactly one item was modified since the last send.

Parameters:

objects - the new list of GroundObjDescriptors in the frame

Returns:

NO_CHANGE if the list hasn't changed. RESEND_ALL if more than one item changed. MODIFY if we modified an item in place.

Throws:

java.lang.Exception

modify

protected void modify(GroundFrame frame,
                      int index)
               throws java.lang.Exception

Modifies an item in place.

Parameters:

frame - the frame containing the new objects in the window

index - the index of the item to resend

Throws:

java.lang.Exception

tryAdd

protected int tryAdd(java.util.List objects,
                     GroundFrame frame)
              throws java.lang.Exception

The new list has one more item than the previous list. Check to see if we just added a single item somewhere in the list.

Parameters:

objects - the new list of GroundObjDescriptors in the frame

Returns:

NO_CHANGE if the list hasn't changed. RESEND_ALL if more than one item changed. MODIFY if we added an item.

Throws:

java.lang.Exception

add

protected void add(GroundFrame frame,
                   int index)
            throws java.lang.Exception

Adds an item from the new frame at the specified index.

Parameters:

frame - the new frame

index - the index at which to add the item

Throws:

java.lang.Exception

tryRemove

protected int tryRemove(java.util.List objects,
                        GroundFrame frame)
                 throws java.lang.Exception

The new list has one less item than the previous list. Check to see if we just removed a single item somewhere in the list.

Parameters:

objects - the new list of GroundObjDescriptors in the frame

Returns:

NO_CHANGE if the list hasn't changed. RESEND_ALL if more than one item changed. MODIFY if we removed an item.

Throws:

java.lang.Exception

sendEmptyList

public void sendEmptyList()
                   throws java.lang.Exception

Sends a blank screen.

Throws:

java.lang.Exception

setMap

public void setMap(GameMap map,
                   int x,
                   int y)

Sets the map for the camera.

Specified by:

setMap in interface Camera

Overrides:

setMap in class AbstractCamera

move

public void move(int xoffset,
                 int yoffset)

Makes sure the GroundCamera is invalidated when it moves.

Specified by:

move in interface Camera

Overrides:

move in class AbstractCamera

Parameters:

xoffset - the map x offset to move by

yoffset - the map y offset to move by

setViewRect

public void setViewRect(Rectangle r)

Resets the view rectangle; dumps the saved-object list.

Specified by:

setViewRect in interface Camera

Overrides:

setViewRect in class AbstractCamera

Parameters:

r - the view rectangle

setViewSize

public void setViewSize(int w,
                        int h)

Changes the view size; dumps the saved-object list.

Specified by:

setViewSize in interface Camera

Overrides:

setViewSize in class AbstractCamera

Parameters:

w - new width

h - new height

getLastFrame

public java.util.List getLastFrame()

Returns the list of objects that were last sent to the client.

Returns:

a list of GroundObjDescriptor objects corresponding to the images & descriptions that were last sent over, in the same order they were sent.

clearLastFrame

public void clearLastFrame()

Nulls out the lastFrame_ field, which forces the next refresh request to go through, even if the contents haven't changed. Used when the client asks to refresh their views.

setShowingSpells

public void setShowingSpells(boolean show)

Turns the display of spells on or off in the Ground View.

Parameters:

show - to show spells in the view.

showingSpells

public boolean showingSpells()

Returns true if we're displaying spells in the ground view. Default is OFF. Settable by the client, by sending a #ground-spells command.

Returns:

true if showing spells.