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*
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* accompanied this code).
*
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package java.awt.event;
import java.awt.AWTEvent;
import java.awt.Component;
import java.awt.Container;
/**
* An event which indicates a change to the {@code Component}
* hierarchy to which {@code Component} belongs.
* <ul>
* <li>Hierarchy Change Events (HierarchyListener)
* <ul>
* <li> addition of an ancestor
* <li> removal of an ancestor
* <li> hierarchy made displayable
* <li> hierarchy made undisplayable
* <li> hierarchy shown on the screen (both visible and displayable)
* <li> hierarchy hidden on the screen (either invisible or undisplayable)
* </ul>
* <li>Ancestor Reshape Events (HierarchyBoundsListener)
* <ul>
* <li> an ancestor was resized
* <li> an ancestor was moved
* </ul>
* </ul>
* <p>
* Hierarchy events are provided for notification purposes ONLY.
* The AWT will automatically handle changes to the hierarchy internally so
* that GUI layout and displayability works properly regardless of whether a
* program is receiving these events or not.
* <p>
* This event is generated by a Container object (such as a Panel) when the
* Container is added, removed, moved, or resized, and passed down the
* hierarchy. It is also generated by a Component object when that object's
* {@code addNotify}, {@code removeNotify}, {@code show}, or
* {@code hide} method is called. The {@code ANCESTOR_MOVED} and
* {@code ANCESTOR_RESIZED}
* events are dispatched to every {@code HierarchyBoundsListener} or
* {@code HierarchyBoundsAdapter} object which registered to receive
* such events using the Component's {@code addHierarchyBoundsListener}
* method. ({@code HierarchyBoundsAdapter} objects implement the
* {@code HierarchyBoundsListener} interface.) The {@code HIERARCHY_CHANGED} events are
* dispatched to every {@code HierarchyListener} object which registered
* to receive such events using the Component's {@code addHierarchyListener}
* method. Each such listener object gets this {@code HierarchyEvent}
* when the event occurs.
* <p>
* An unspecified behavior will be caused if the {@code id} parameter
* of any particular {@code HierarchyEvent} instance is not
* in the range from {@code HIERARCHY_FIRST} to {@code HIERARCHY_LAST}.
* <br>
* The {@code changeFlags} parameter of any {@code HierarchyEvent} instance takes one of the following
* values:
* <ul>
* <li> {@code HierarchyEvent.PARENT_CHANGED}
* <li> {@code HierarchyEvent.DISPLAYABILITY_CHANGED}
* <li> {@code HierarchyEvent.SHOWING_CHANGED}
* </ul>
* Assigning the value different from listed above will cause unspecified behavior.
*
* @author David Mendenhall
* @see HierarchyListener
* @see HierarchyBoundsAdapter
* @see HierarchyBoundsListener
* @since 1.3
*/
public class HierarchyEvent extends AWTEvent {
/*
* serialVersionUID
*/
private static final long serialVersionUID = -5337576970038043990L;
/**
* Marks the first integer id for the range of hierarchy event ids.
*/
public static final int HIERARCHY_FIRST = 1400; // 1300 used by sun.awt.windows.ModalityEvent
/**
* The event id indicating that modification was made to the
* entire hierarchy tree.
*/
public static final int HIERARCHY_CHANGED = HIERARCHY_FIRST;
/**
* The event id indicating an ancestor-Container was moved.
*/
public static final int ANCESTOR_MOVED = 1 + HIERARCHY_FIRST;
/**
* The event id indicating an ancestor-Container was resized.
*/
public static final int ANCESTOR_RESIZED = 2 + HIERARCHY_FIRST;
/**
* Marks the last integer id for the range of ancestor event ids.
*/
public static final int HIERARCHY_LAST = ANCESTOR_RESIZED;
/**
* A change flag indicates that the {@code HIERARCHY_CHANGED} event
* was generated by a reparenting operation.
*/
public static final int PARENT_CHANGED = 0x1;
/**
* A change flag indicates that the {@code HIERARCHY_CHANGED} event
* was generated due to the changing of the hierarchy displayability.
* To discern the
* current displayability of the hierarchy, call the
* {@code Component.isDisplayable} method. Displayability changes occur
* in response to explicit or implicit calls of the
* {@code Component.addNotify} and
* {@code Component.removeNotify} methods.
*
* @see java.awt.Component#isDisplayable()
* @see java.awt.Component#addNotify()
* @see java.awt.Component#removeNotify()
*/
public static final int DISPLAYABILITY_CHANGED = 0x2;
/**
* A change flag indicates that the {@code HIERARCHY_CHANGED} event
* was generated due to the changing of the hierarchy showing state.
* To discern the
* current showing state of the hierarchy, call the
* {@code Component.isShowing} method. Showing state changes occur
* when either the displayability or visibility of the
* hierarchy occurs. Visibility changes occur in response to explicit
* or implicit calls of the {@code Component.show} and
* {@code Component.hide} methods.
*
* @see java.awt.Component#isShowing()
* @see java.awt.Component#addNotify()
* @see java.awt.Component#removeNotify()
* @see java.awt.Component#show()
* @see java.awt.Component#hide()
*/
public static final int SHOWING_CHANGED = 0x4;
Component changed;
Container changedParent;
long changeFlags;
/**
* Constructs an {@code HierarchyEvent} object to identify a
* change in the {@code Component} hierarchy.
* <p>This method throws an
* {@code IllegalArgumentException} if {@code source}
* is {@code null}.
*
* @param source The {@code Component} object that
* originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @param changed The {@code Component} at the top of
* the hierarchy which was changed
* @param changedParent The parent of the {@code changed} component.
* This
* may be the parent before or after the
* change, depending on the type of change
* @throws IllegalArgumentException if {@code source} is {@code null}
* @see #getSource()
* @see #getID()
* @see #getChanged()
* @see #getChangedParent()
*/
public HierarchyEvent(Component source, int id, Component changed,
Container changedParent) {
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
}
/**
* Constructs an {@code HierarchyEvent} object to identify
* a change in the {@code Component} hierarchy.
* <p> This method throws an
* {@code IllegalArgumentException} if {@code source}
* is {@code null}.
*
* @param source The {@code Component} object that
* originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @param changed The {@code Component} at the top
* of the hierarchy which was changed
* @param changedParent The parent of the {@code changed} component.
* This
* may be the parent before or after the
* change, depending on the type of change
* @param changeFlags A bitmask which indicates the type(s) of
* the {@code HIERARCHY_CHANGED} events
* represented in this event object.
* For information on allowable values, see
* the class description for {@link HierarchyEvent}
* @throws IllegalArgumentException if {@code source} is null
* @see #getSource()
* @see #getID()
* @see #getChanged()
* @see #getChangedParent()
* @see #getChangeFlags()
*/
public HierarchyEvent(Component source, int id, Component changed,
Container changedParent, long changeFlags) {
super(source, id);
this.changed = changed;
this.changedParent = changedParent;
this.changeFlags = changeFlags;
}
/**
* Returns the originator of the event.
*
* @return the {@code Component} object that originated
* the event, or {@code null} if the object is not a
* {@code Component}.
*/
public Component getComponent() {
return (source instanceof Component) ? (Component)source : null;
}
/**
* Returns the Component at the top of the hierarchy which was
* changed.
*
* @return the changed Component
*/
public Component getChanged() {
return changed;
}
/**
* Returns the parent of the Component returned by
* {@code getChanged()}. For a HIERARCHY_CHANGED event where the
* change was of type PARENT_CHANGED via a call to
* {@code Container.add}, the parent returned is the parent
* after the add operation. For a HIERARCHY_CHANGED event where
* the change was of type PARENT_CHANGED via a call to
* {@code Container.remove}, the parent returned is the parent
* before the remove operation. For all other events and types,
* the parent returned is the parent during the operation.
*
* @return the parent of the changed Component
*/
public Container getChangedParent() {
return changedParent;
}
/**
* Returns a bitmask which indicates the type(s) of
* HIERARCHY_CHANGED events represented in this event object.
* The bits have been bitwise-ored together.
*
* @return the bitmask, or 0 if this is not an HIERARCHY_CHANGED
* event
*/
public long getChangeFlags() {
return changeFlags;
}
/**
* Returns a parameter string identifying this event.
* This method is useful for event-logging and for debugging.
*
* @return a string identifying the event and its attributes
*/
public String paramString() {
String typeStr;
switch(id) {
case ANCESTOR_MOVED:
typeStr = "ANCESTOR_MOVED ("+changed+","+changedParent+")";
break;
case ANCESTOR_RESIZED:
typeStr = "ANCESTOR_RESIZED ("+changed+","+changedParent+")";
break;
case HIERARCHY_CHANGED: {
typeStr = "HIERARCHY_CHANGED (";
boolean first = true;
if ((changeFlags & PARENT_CHANGED) != 0) {
first = false;
typeStr += "PARENT_CHANGED";
}
if ((changeFlags & DISPLAYABILITY_CHANGED) != 0) {
if (first) {
first = false;
} else {
typeStr += ",";
}
typeStr += "DISPLAYABILITY_CHANGED";
}
if ((changeFlags & SHOWING_CHANGED) != 0) {
if (first) {
first = false;
} else {
typeStr += ",";
}
typeStr += "SHOWING_CHANGED";
}
if (!first) {
typeStr += ",";
}
typeStr += changed + "," + changedParent + ")";
break;
}
default:
typeStr = "unknown type";
}
return typeStr;
}
}