/*******************************************************************************
* Copyright (c) 2002, 2010 Innoopract Informationssysteme GmbH.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Innoopract Informationssysteme GmbH - initial API and implementation
* EclipseSource - ongoing development
******************************************************************************/
package org.eclipse.swt.widgets;
import org.eclipse.rwt.Adaptable;
import org.eclipse.rwt.internal.AdapterManager;
import org.eclipse.rwt.internal.AdapterManagerImpl;
import org.eclipse.rwt.internal.events.EventAdapter;
import org.eclipse.rwt.internal.events.IEventAdapter;
import org.eclipse.rwt.internal.theme.*;
import org.eclipse.rwt.lifecycle.IWidgetAdapter;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.internal.widgets.*;
/**
* This class is the abstract superclass of all user interface objects.
* Widgets are created, disposed and issue notification to listeners
* when events occur which affect them.
* <dl>
* <dt><b>Styles:</b></dt>
* <dd>(none)</dd>
* <dt><b>Events:</b></dt>
* <dd>Dispose</dd>
* </dl>
* <p>
* IMPORTANT: This class is intended to be subclassed <em>only</em>
* within the SWT implementation. However, it has not been marked
* final to allow those outside of the SWT development team to implement
* patched versions of the class in order to get around specific
* limitations in advance of when those limitations can be addressed
* by the team. Any class built using subclassing to access the internals
* of this class will likely fail to compile or run between releases and
* may be strongly platform specific. Subclassing should not be attempted
* without an intimate and detailed understanding of the workings of the
* hierarchy. No support is provided for user-written classes which are
* implemented as subclasses of this class.
* </p>
* <p>Even though this class implements <code>Adaptable</code> this interface
* is <em>not</em> part of the RWT public API. It is only meant to be shared
* within the packages provided by RWT and should never be accessed from
* application code.
* </p>
*
* @see #checkSubclass
* @since 1.0
*/
public abstract class Widget implements Adaptable {
/* Default size for widgets */
static final int DEFAULT_WIDTH = 64;
static final int DEFAULT_HEIGHT = 64;
/* Global state flags */
static final int DISPOSED = 1 << 0;
// static final int CANVAS = 1 << 1;
static final int KEYED_DATA = 1 << 2;
static final int DISABLED = 1 << 3;
static final int HIDDEN = 1 << 4;
/* A layout was requested on this widget */
static final int LAYOUT_NEEDED = 1 << 5;
/* The preferred size of a child has changed */
static final int LAYOUT_CHANGED = 1 << 6;
/* A layout was requested in this widget hierarchy */
static final int LAYOUT_CHILD = 1 << 7;
/* Background flags */
static final int THEME_BACKGROUND = 1 << 8;
static final int PARENT_BACKGROUND = 1 << 10;
/* Dispose and release flags */
static final int RELEASED = 1 << 11;
static final int DISPOSE_SENT = 1 << 12;
/* Notify of the opportunity to skin this widget */
static final int SKIN_NEEDED = 1 << 21;
int style;
int state;
Display display;
private Object data;
private AdapterManager adapterManager;
private IWidgetAdapter widgetAdapter;
private IEventAdapter eventAdapter;
private UntypedEventAdapter untypedAdapter;
private IWidgetGraphicsAdapter widgetGraphicsAdapter;
Widget() {
// prevent instantiation from outside this package
}
/**
* Constructs a new instance of this class given its parent
* and a style value describing its behavior and appearance.
* <p>
* The style value is either one of the style constants defined in
* class <code>SWT</code> which is applicable to instances of this
* class, or must be built by <em>bitwise OR</em>'ing together
* (that is, using the <code>int</code> "|" operator) two or more
* of those <code>SWT</code> style constants. The class description
* lists the style constants that are applicable to the class.
* Style bits are also inherited from superclasses.
* </p>
*
* @param parent a widget which will be the parent of the new instance (cannot be null)
* @param style the style of widget to construct
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
* <li>ERROR_INVALID_ARGUMENT - if the parent is disposed</li>
* </ul>
* @exception SWTException <ul>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
* <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
* </ul>
*
* @see SWT
* @see #checkSubclass
* @see #getStyle
*/
public Widget( final Widget parent, final int style ) {
checkSubclass();
if( parent == null ) {
SWT.error( SWT.ERROR_NULL_ARGUMENT );
}
this.style = style;
this.display = parent.display;
reskinWidget();
}
/**
* Implementation of the <code>Adaptable</code> interface.
* <p><strong>IMPORTANT:</strong> This method is <em>not</em> part of the RWT
* public API. It is marked public only so that it can be shared
* within the packages provided by RWT. It should never be accessed
* from application code.
* </p>
*/
public Object getAdapter( final Class adapter ) {
Object result;
if( adapter == IEventAdapter.class ) {
// Note: This is not implemented via the AdapterManager, since the
// manager's mapping mechanism prevents the component being released
// unless the session is invalidated.
if( eventAdapter == null ) {
eventAdapter = new EventAdapter();
}
result = eventAdapter;
} else if( adapter == IWidgetAdapter.class ) {
// [fappel] Directly return the WidgetAdapter instead of consulting the
// adapter factory. This is done for performance reasons and must not
// be changed without good reason.
if( widgetAdapter == null ) {
widgetAdapter = new WidgetAdapter();
}
result = widgetAdapter;
} else if( adapter == IThemeAdapter.class ) {
// This also bypasses the AdapterManager for the sake of performance.
// ThemeAdapters are requested frequently during size computations.
result = ThemeAdapterUtil.getThemeAdapter( this );
} else if( adapter == IWidgetGraphicsAdapter.class ) {
if( widgetGraphicsAdapter == null ) {
widgetGraphicsAdapter = new WidgetGraphicsAdapter();
}
result = widgetGraphicsAdapter;
} else {
// [fappel] Buffer the adapterManager to improve performance
if( adapterManager == null ) {
adapterManager = AdapterManagerImpl.getInstance();
}
result = adapterManager.getAdapter( this, adapter );
}
return result;
}
///////////////////////////////////////////
// Methods to get/set single and keyed data
/**
* Returns the application defined widget data associated
* with the receiver, or null if it has not been set. The
* <em>widget data</em> is a single, unnamed field that is
* stored with every widget.
* <p>
* Applications may put arbitrary objects in this field. If
* the object stored in the widget data needs to be notified
* when the widget is disposed of, it is the application's
* responsibility to hook the Dispose event on the widget and
* do so.
* </p>
*
* @return the widget data
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - when the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - when called from the wrong thread</li>
* </ul>
*
* @see #setData(Object)
*/
public Object getData() {
checkWidget();
return ( state & KEYED_DATA ) != 0 ? ( ( Object[] )data )[ 0 ] : data;
}
/**
* Sets the application defined widget data associated
* with the receiver to be the argument. The <em>widget
* data</em> is a single, unnamed field that is stored
* with every widget.
* <p>
* Applications may put arbitrary objects in this field. If
* the object stored in the widget data needs to be notified
* when the widget is disposed of, it is the application's
* responsibility to hook the Dispose event on the widget and
* do so.
* </p>
*
* @param data the widget data
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - when the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - when called from the wrong thread</li>
* </ul>
*
* @see #getData()
*/
public void setData( final Object data ) {
checkWidget();
if( ( state & KEYED_DATA ) != 0 ) {
( ( Object[] )this.data )[ 0 ] = data;
} else {
this.data = data;
}
}
/**
* Returns the application defined property of the receiver
* with the specified name, or null if it has not been set.
* <p>
* Applications may have associated arbitrary objects with the
* receiver in this fashion. If the objects stored in the
* properties need to be notified when the widget is disposed
* of, it is the application's responsibility to hook the
* Dispose event on the widget and do so.
* </p>
*
* @param key the name of the property
* @return the value of the property or null if it has not been set
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the key is null</li>
* </ul>
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see #setData(String, Object)
*/
public Object getData( final String key ) {
// Must not call checkWidget() here to allow to obtain the custom id after
// the widget has been disposed of (see WidgetUtil#getId). Only validate
// thread.
if( !isValidThread() ) {
error( SWT.ERROR_THREAD_INVALID_ACCESS );
}
if( key == null ) {
error( SWT.ERROR_NULL_ARGUMENT );
}
Object result = null;
if( ( state & KEYED_DATA ) != 0 ) {
Object[] table = ( Object[] )data;
for( int i = 1; result == null && i < table.length; i += 2 ) {
if( key.equals( table[ i ] ) ) {
result = table[ i + 1 ];
}
}
}
return result;
}
/**
* Sets the application defined property of the receiver
* with the specified name to the given value.
* <p>
* Applications may associate arbitrary objects with the
* receiver in this fashion. If the objects stored in the
* properties need to be notified when the widget is disposed
* of, it is the application's responsibility to hook the
* Dispose event on the widget and do so.
* </p>
*
* @param key the name of the property
* @param value the new value for the property
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the key is null</li>
* </ul>
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see #getData(String)
*/
public void setData( final String key, final Object value ) {
checkWidget();
if( key == null ) {
error( SWT.ERROR_NULL_ARGUMENT );
}
int index = 1;
Object[] table = null;
if( ( state & KEYED_DATA ) != 0 ) {
table = ( Object[] )data;
while( index < table.length ) {
if( key.equals( table[ index ] ) ) {
break;
}
index += 2;
}
}
if( value != null ) {
if( ( state & KEYED_DATA ) != 0 ) {
if( index == table.length ) {
Object[] newTable = new Object[ table.length + 2 ];
System.arraycopy( table, 0, newTable, 0, table.length );
data = table = newTable;
}
} else {
table = new Object[ 3 ];
table[ 0 ] = data;
data = table;
state |= KEYED_DATA;
}
table[ index ] = key;
table[ index + 1 ] = value;
} else {
if( ( state & KEYED_DATA ) != 0 ) {
if( index != table.length ) {
int length = table.length - 2;
if( length == 1 ) {
data = table[ 0 ];
state &= ~KEYED_DATA;
} else {
Object[] newTable = new Object[ length ];
System.arraycopy( table, 0, newTable, 0, index );
System.arraycopy( table, index + 2, newTable, index, length - index );
data = newTable;
}
}
}
}
if( key.equals( SWT.SKIN_CLASS ) || key.equals( SWT.SKIN_ID ) ) {
reskin( SWT.ALL );
}
}
/**
* Returns the <code>Display</code> that is associated with
* the receiver.
* <p>
* A widget's display is either provided when it is created
* (for example, top level <code>Shell</code>s) or is the
* same as its parent's display.
* </p>
*
* @return the receiver's display
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* </ul>
*/
public Display getDisplay() {
// do not check control for UI Thread, see bug #193389
Display display = this.display;
// if( display == null )
// error( SWT.ERROR_WIDGET_DISPOSED );
return display;
}
/**
* Returns the receiver's style information.
* <p>
* Note that the value which is returned by this method <em>may
* not match</em> the value which was provided to the constructor
* when the receiver was created. This can occur when the underlying
* operating system does not support a particular combination of
* requested styles. For example, if the platform widget used to
* implement a particular SWT widget always has scroll bars, the
* result of calling this method would always have the
* <code>SWT.H_SCROLL</code> and <code>SWT.V_SCROLL</code> bits set.
* </p>
*
* @return the style bits
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*/
public int getStyle() {
checkWidget();
return style;
}
///////////////////////////////////////////////
// Registration and deregistration of listeners
/**
* Adds the listener to the collection of listeners who will
* be notified when the widget is disposed. When the widget is
* disposed, the listener is notified by sending it the
* <code>widgetDisposed()</code> message.
*
* @param listener the listener which should be notified when the receiver is disposed
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see DisposeListener
* @see #removeDisposeListener
*/
public void addDisposeListener( final DisposeListener listener ) {
checkWidget();
DisposeEvent.addListener( this, listener );
}
/**
* Removes the listener from the collection of listeners who will
* be notified when the widget is disposed.
*
* @param listener the listener which should no longer be notified when the receiver is disposed
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see DisposeListener
* @see #addDisposeListener
*/
public void removeDisposeListener( final DisposeListener listener ) {
checkWidget();
DisposeEvent.removeListener( this, listener );
}
////////////////////////////////////////
// Methods for untyped listener handling
/**
* Adds the listener to the collection of listeners who will be notified when
* an event of the given type occurs. When the event does occur in the widget,
* the listener is notified by sending it the <code>handleEvent()</code>
* message. The event type is one of the event constants defined in class
* <code>SWT</code>.
*
* @param eventType the type of event to listen for
* @param listener the listener which should be notified when the event occurs
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
* @see Listener
* @see SWT
* @see #removeListener
* @see #notifyListeners
*/
public void addListener( final int eventType, final Listener listener ) {
checkWidget();
if( listener == null ) {
error( SWT.ERROR_NULL_ARGUMENT );
}
if( untypedAdapter == null ) {
untypedAdapter = new UntypedEventAdapter();
}
untypedAdapter.addListener( this, eventType, listener );
}
/**
* Removes the listener from the collection of listeners who will be notified
* when an event of the given type occurs. The event type is one of the event
* constants defined in class <code>SWT</code>.
*
* @param eventType the type of event to listen for
* @param listener the listener which should no longer be notified when the
* event occurs
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
* @see Listener
* @see SWT
* @see #addListener
* @see #notifyListeners
*/
public void removeListener( final int eventType, final Listener listener ) {
checkWidget();
if( listener == null ) {
error( SWT.ERROR_NULL_ARGUMENT );
}
if( untypedAdapter != null ) {
untypedAdapter.removeListener( this, eventType, listener );
if( untypedAdapter.isEmpty() ) {
untypedAdapter = null;
}
}
}
/**
* Notifies all of the receiver's listeners for events
* of the given type that one such event has occurred by
* invoking their <code>handleEvent()</code> method. The
* event type is one of the event constants defined in class
* <code>SWT</code>.
*
* @param eventType the type of event which has occurred
* @param event the event data
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see SWT
* @see #addListener
* @see #getListeners(int)
* @see #removeListener(int, Listener)
* @since 1.2
*/
public void notifyListeners( final int eventType, final Event event ) {
checkWidget();
Event newEvent = event == null ? new Event() : event;
newEvent.widget = this;
newEvent.type = eventType;
newEvent.display = display;
UntypedEventAdapter.notifyListeners( eventType, newEvent );
}
/**
* Returns <code>true</code> if there are any listeners
* for the specified event type associated with the receiver,
* and <code>false</code> otherwise. The event type is one of
* the event constants defined in class <code>SWT</code>.
*
* @param eventType the type of event
* @return true if the event is hooked
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see SWT
* @since 1.3
*/
public boolean isListening( final int eventType ) {
checkWidget();
boolean result = false;
if( untypedAdapter != null ) {
result = untypedAdapter.hasUntypedListener( eventType );
}
if( !result ) {
result = UntypedEventAdapter.hasTypedListener( this, eventType );
}
return result;
}
/**
* Returns an array of listeners who will be notified when an event
* of the given type occurs. The event type is one of the event constants
* defined in class <code>SWT</code>.
*
* @param eventType the type of event to listen for
* @return an array of listeners that will be notified when the event occurs
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see Listener
* @see SWT
* @see #addListener(int, Listener)
* @see #removeListener(int, Listener)
* @see #notifyListeners
*
* @since 1.3
*/
public Listener[] getListeners( final int eventType ) {
checkWidget();
Listener[] listeners;
if( untypedAdapter == null ) {
listeners = new Listener[ 0 ];
} else {
listeners = untypedAdapter.getListeners( eventType );
}
return listeners;
}
///////////////////
// Skinning support
/**
* Marks the widget to be skinned.
* <p>
* The skin event is sent to the receiver's display when appropriate (usually before the next event
* is handled). Widgets are automatically marked for skinning upon creation as well as when its skin
* id or class changes. The skin id and/or class can be changed by calling <code>Display.setData(String, Object)</code>
* with the keys SWT.SKIN_ID and/or SWT.SKIN_CLASS. Once the skin event is sent to a widget, it
* will not be sent again unless <code>reskin(int)</code> is called on the widget or on an ancestor
* while specifying the <code>SWT.ALL</code> flag.
* </p>
* <p>
* The parameter <code>flags</code> may be either:
* <dl>
* <dt><b>SWT.ALL</b></dt>
* <dd>all children in the receiver's widget tree should be skinned</dd>
* <dt><b>SWT.NONE</b></dt>
* <dd>only the receiver should be skinned</dd>
* </dl>
* </p>
* @param flags the flags specifying how to reskin
*
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
* @since 1.3
*/
public void reskin( final int flags ) {
checkWidget();
reskinWidget();
if( ( flags & SWT.ALL ) != 0 ) {
reskinChildren( flags );
}
}
void reskinChildren( final int flags ) {
}
void reskinWidget() {
if( ( state & SKIN_NEEDED ) != SKIN_NEEDED ) {
this.state |= SKIN_NEEDED;
display.addSkinnableWidget( this );
}
}
///////////////////////
// toString and helpers
/**
* Returns a string containing a concise, human-readable
* description of the receiver.
*
* @return a string representation of the receiver
*/
public String toString() {
String string = "*Disposed*";
if( !isDisposed() ) {
string = "*Wrong Thread*";
if( isValidThread() ) {
string = getNameText();
}
}
return getName() + " {" + string + "}";
}
/**
* Returns the name of the widget. This is the name of
* the class without the package name.
*
* @return the name of the widget
*/
String getName() {
String string = getClass().getName();
int index = string.lastIndexOf( '.' );
if( index != -1 ) {
string = string.substring( index + 1, string.length() );
}
return string;
}
/*
* Returns a short printable representation for the contents
* of a widget. For example, a button may answer the label
* text. This is used by <code>toString</code> to provide a
* more meaningful description of the widget.
*
* @return the contents string for the widget
*
* @see #toString
*/
String getNameText() {
return "";
}
///////////////////////////////////
// Methods to dispose of the widget
/**
* Disposes of the operating system resources associated with
* the receiver and all its descendents. After this method has
* been invoked, the receiver and all descendents will answer
* <code>true</code> when sent the message <code>isDisposed()</code>.
* Any internal connections between the widgets in the tree will
* have been removed to facilitate garbage collection.
* <p>
* NOTE: This method is not called recursively on the descendents
* of the receiver. This means that, widget implementers can not
* detect when a widget is being disposed of by re-implementing
* this method, but should instead listen for the <code>Dispose</code>
* event.
* </p>
*
* @exception SWTException <ul>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*
* @see #addDisposeListener
* @see #removeDisposeListener
* @see #checkWidget
*/
// TODO [rh] ensure that this implementation aligns with SWT rules for
// disposing (see The Standard Widget Toolkit, p 13)
public void dispose() {
if( !isDisposed() ) {
if( !isValidThread() ) {
error( SWT.ERROR_THREAD_INVALID_ACCESS );
}
if( ( state & DISPOSE_SENT ) == 0 ) {
state |= DISPOSE_SENT;
DisposeEvent disposeEvent = new DisposeEvent( this );
disposeEvent.processEvent();
}
releaseChildren();
releaseParent();
releaseWidget();
// TODO [rh] think about a better solution to propagate widget disposal
// to the LCA
IWidgetAdapter adapter
= ( IWidgetAdapter )getAdapter( IWidgetAdapter.class );
adapter.markDisposed( this );
}
}
/**
* Returns <code>true</code> if the widget has been disposed,
* and <code>false</code> otherwise.
* <p>
* This method gets the dispose state for the widget.
* When a widget has been disposed, it is an error to
* invoke any other method using the widget.
* </p>
*
* @return <code>true</code> when the widget is disposed and <code>false</code> otherwise
*/
public boolean isDisposed() {
return ( state & DISPOSED ) != 0;
}
boolean isInDispose() {
return ( state & Widget.DISPOSE_SENT ) != 0;
}
void releaseChildren() {
// do nothing - derived classes may override
}
void releaseParent() {
// do nothing - derived classes may override
}
void releaseWidget() {
adapterManager = null;
untypedAdapter = null;
state |= DISPOSED;
}
/**
* Checks that this class can be subclassed.
* <p>
* The SWT class library is intended to be subclassed
* only at specific, controlled points (most notably,
* <code>Composite</code> and <code>Canvas</code> when
* implementing new widgets). This method enforces this
* rule unless it is overridden.
* </p><p>
* <em>IMPORTANT:</em> By providing an implementation of this
* method that allows a subclass of a class which does not
* normally allow subclassing to be created, the implementer
* agrees to be fully responsible for the fact that any such
* subclass will likely fail between SWT releases and will be
* strongly platform specific. No support is provided for
* user-written classes which are implemented in this fashion.
* </p><p>
* The ability to subclass outside of the allowed SWT classes
* is intended purely to enable those not on the SWT development
* team to implement patches in order to get around specific
* limitations in advance of when those limitations can be
* addressed by the team. Subclassing should not be attempted
* without an intimate and detailed understanding of the hierarchy.
* </p>
*
* @exception SWTException <ul>
* <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
* </ul>
*/
protected void checkSubclass() {
if( !isValidSubclass() ) {
error( SWT.ERROR_INVALID_SUBCLASS );
}
}
/*
* Returns <code>true</code> when subclassing is
* allowed and <code>false</code> otherwise
*
* @return <code>true</code> when subclassing is allowed and <code>false</code> otherwise
*/
boolean isValidSubclass() {
return Display.isValidClass( getClass() );
}
/**
* Throws an <code>SWTException</code> if the receiver can not
* be accessed by the caller. This may include both checks on
* the state of the receiver and more generally on the entire
* execution context. This method <em>should</em> be called by
* widget implementors to enforce the standard SWT invariants.
* <p>
* Currently, it is an error to invoke any method (other than
* <code>isDisposed()</code>) on a widget that has had its
* <code>dispose()</code> method called. It is also an error
* to call widget methods from any thread that is different
* from the thread that created the widget.
* </p><p>
* In future releases of SWT, there may be more or fewer error
* checks and exceptions may be thrown for different reasons.
* </p>
*
* @exception SWTException <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
* </ul>
*/
protected void checkWidget() {
if( !isValidThread() ) {
error( SWT.ERROR_THREAD_INVALID_ACCESS );
}
if( ( state & DISPOSED ) != 0 ) {
error( SWT.ERROR_WIDGET_DISPOSED );
}
}
/*
* Returns <code>true</code> when the current thread is
* the thread that created the widget and <code>false</code>
* otherwise.
*
* @return <code>true</code> when the current thread is the thread that
* created the widget and <code>false</code> otherwise
*/
boolean isValidThread() {
return getDisplay().getThread() == Thread.currentThread();
}
static int checkBits( final int style,
final int int0,
final int int1,
final int int2,
final int int3,
final int int4,
final int int5 )
{
int mask = int0 | int1 | int2 | int3 | int4 | int5;
int result = style;
if( ( result & mask ) == 0 ) {
result |= int0;
}
if( ( result & int0 ) != 0 ) {
result = ( result & ~mask ) | int0;
}
if( ( result & int1 ) != 0 ) {
result = ( result & ~mask ) | int1;
}
if( ( result & int2 ) != 0 ) {
result = ( result & ~mask ) | int2;
}
if( ( result & int3 ) != 0 ) {
result = ( result & ~mask ) | int3;
}
if( ( result & int4 ) != 0 ) {
result = ( result & ~mask ) | int4;
}
if( ( result & int5 ) != 0 ) {
result = ( result & ~mask ) | int5;
}
return result;
}
// verbatim copy of SWT code
void checkOrientation (Widget parent) {
//style &= ~SWT.MIRRORED;
if ((style & (SWT.LEFT_TO_RIGHT /*| SWT.RIGHT_TO_LEFT*/)) == 0) {
if (parent != null) {
if ((parent.style & SWT.LEFT_TO_RIGHT) != 0) style |= SWT.LEFT_TO_RIGHT;
/*if ((parent.style & SWT.RIGHT_TO_LEFT) != 0) style |= SWT.RIGHT_TO_LEFT;*/
}
}
style = checkBits (style, SWT.LEFT_TO_RIGHT, 0 /*SWT.RIGHT_TO_LEFT*/, 0, 0, 0, 0);
}
void error( final int code ) {
SWT.error( code );
}
}