MediaTracker

Name

Description

The MediaTracker class assists in the loading of multimedia objects across the network. It can be used to wait until an object (or group of objects) has been loaded completely. Tracked objects are assigned to groups; if there is more than one object in a group, you can only track the behavior of the group as a whole (i.e., it isn't possible to track an individual object unless it is the only object in its group). Currently (1.0.2 and 1.1) MediaTracker only works for Image objects; future releases may extend MediaTracker to other multi-media types.

Class Definition

public abstract class java.awt.MediaTracker extends java.lang.Object implements java.io.Serializable {
 // Constants public static final int ABORTED;
public static final int COMPLETE;
public static final int ERRORED;
public static final int LOADING; // Constructors public MediaTracker (Component component); // Instance Methods public void addImage (Image image, int id);
public synchronized void addImage (Image image, int id, int width, int height);
public boolean checkAll();
public synchronized boolean checkAll (boolean load);
public boolean checkID (int id);
public synchronized boolean checkID (int id, boolean load);
public synchronized Object[] getErrorsAny();
public synchronized Object[] getErrorsID (int id);
public synchronized boolean isErrorAny();
public synchronized boolean isErrorID (int id);
public synchronized void removeImage(Image image); public synchronized void removeImage(Image image, int id); public synchronized void removeImage(Image image, int id, int width, int height); public synchronized int statusAll (boolean load);
public synchronized int statusID (int id, boolean load);
public void waitForAll() throws InterruptedException;
public synchronized boolean waitForAll (long ms) throws InterruptedException;
public void waitForID (int id) throws InterruptedException;
public synchronized boolean waitForID (int id, long ms) throws InterruptedException;
}

Constants

ABORTED

public static final int ABORTED

Flag that indicates that the loading process aborted while loading a particular image.

COMPLETE

public static final int COMPLETE

Flag that indicates a particular image loaded successfully.

ERRORED

public static final int ERRORED

Flag that indicates an error occurred while a particular image was loading.

LOADING

public static final int LOADING

Flag that indicates a particular image is still loading.

Constructors

MediaTracker

public MediaTracker (Component component)

• Parameters
• • component
  • Component that eventually renders objects being tracked.
• Description
• Constructs an MediaTracker object.

Instance Methods

addImage

public void addImage (Image image, int id)

• Parameters
• • image
  • Image to track.
  • id
  • ID of a group.
• Description
• Tells a MediaTracker to track the loading of image, placing the image in the group identified by id.

public synchronized void addImage (Image image, int id, int width, int height)

• Parameters
• • image
  • Image to track.
  • id
  • ID of a group.
  • width
  • Eventual rendering width.
  • height
  • Eventual rendering height.
• Description
• Tells a MediaTracker to track the loading of image, which will be scaled to the given height and width, placing the image in the group identified by id.

checkAll

public boolean checkAll()

• Returns
• true if images completed loading (successfully or unsuccessfully), false otherwise.
• Description
• Determines if all images have finished loading.

public synchronized boolean checkAll (boolean load)

• Parameters
• • load
  • Flag to force image loading to start.
• Returns
• true if all images have completed loading (successfully or unsuccessfully), false otherwise.
• Description
• Determines if all images have finished loading; the load parameter may be used to force images to start loading.

checkID

public boolean checkID (int id)

• Parameters
• • id
  • ID of a group.
• Returns
• true if all images have completed loading (successfully or unsuccessfully), false otherwise.
• Description
• Determines if all images with the given ID tag have finished loading.

public synchronized boolean checkID (int id, boolean load)

• Parameters
• • id
  • ID of a group.
  • load
  • Flag to force image loading to start.
• Returns
• true if all images have completed loading (successfully or unsuccessfully), false otherwise.
• Description
• Determines if all images with the given ID tag have finished loading; the load parameter may be used to force images to start loading.

getErrorsAny

public synchronized Object[] getErrorsAny()

• Returns
• An array of objects managed by this media tracker that encountered a loading error.
• Description
• Checks to see if any media encountered an error while loading.

getErrorsID

public synchronized Object[] getErrorsID (int id)

• Parameters
• • id
  • ID of a group.
• Returns
• An array of objects that encountered a loading error.
• Description
• Checks to see if any media with the given ID tag encountered an error while loading.

isErrorAny

public synchronized boolean isErrorAny()

• Returns
• true if an error occurred, false otherwise.
• Description
• Checks to see if any media monitored by this media tracker encountered an error while loading.

isErrorID

public synchronized boolean isErrorID (int id)

• Parameters
• • id
  • ID of a group.
• Returns
• true if error happened, false otherwise.
• Description
• Checks to see if any media in the given group encountered an error while loading.

removeImage

public synchronized void removeImage (Image image)

• Parameters
• • image
  • The image to remove.
• Description
• Removes the specified image from this MediaTracker.

public synchronized void removeImage (Image image, int id)

• Parameters
• • image
  • The image to remove.
  • id
  • ID of a group.
• Description
• Removes the specified image from this MediaTracker. Only instances matching the given id will be removed.

public synchronized void removeImage (Image image, int id, int width, int height)

• Parameters
• • image
  • The image to remove.
  • id
  • ID of a group.
  • width
  • Width of the scaled image, or -1 for unscaled.
  • height
  • Height of the scaled image, or -1 for unscaled.
• Description
• Removes the specified image from this MediaTracker. Only instances matching the given id and scale sizes will be removed.

statusAll

public synchronized int statusAll (boolean load)

• Parameters
• • load
  • Flag to force image loading to start.
• Returns
• MediaTracker status flags ORed together.
• Description
• Checks load status of all the images monitored by this media tracker; the load parameter may be used to force images to start loading.

statusID

public synchronized int statusID (int id, boolean load)

• Parameters
• • id
  • ID of a group.
  • load
  • Flag to force image loading to start.
• Returns
• MediaTracker status flags ORed together.
• Description
• Checks load status of all the images in the given group; the load parameter may be used to force images to start loading.

waitForAll

public void waitForAll() throws InterruptedException

• Throws
• • InterruptedException
  • If waiting interrupted.
• Description
• Waits for all the images monitored by this media tracker to load.

public synchronized boolean waitForAll (long ms) throws InterruptedException

• Parameters
• • ms
  • Time to wait for loading.
• Throws
• • InterruptedException
  • If waiting interrupted.
• Returns
• true if images fully loaded, false otherwise.
• Description
• Waits at most ms milliseconds for all images monitored by this media tracker to load.

waitForID

public void waitForID (int id) throws InterruptedException

• Parameters
• • id
  • ID of a group.
• Throws
• • InterruptedException
  • If waiting interrupted.
• Description
• Waits for images in the given group to load.

public synchronized boolean waitForID (int id, long ms) throws InterruptedException

• Parameters
• • id
  • ID of a group.
  • ms
  • Maximum time to wait for loading.
• Throws
• • InterruptedException
  • If waiting interrupted.
• Returns
• true if images fully loaded, false otherwise.
• Description
• Waits at most ms milliseconds for the images in the given group to load.

See Also

Component, Image, Object