Widget

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>Styles:</dt> <dd>(none)</dd> <dt>Events:</dt> <dd>Dispose</dd> </dl> IMPORTANT: This class is intended to be subclassed only 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.

@see #checkSubclass @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>

abstract

class Widget {

GtkWidget* handle;

int style;

int state;

Display display;

EventTable eventTable;

Object data;

int DISPOSED;

int CANVAS;

int KEYED_DATA;

int HANDLE;

int DISABLED;

int MENU;

int OBSCURED;

int MOVED;

int RESIZED;

int ZERO_WIDTH;

int ZERO_HEIGHT;

int HIDDEN;

int FOREGROUND;

int BACKGROUND;

int FONT;

int PARENT_BACKGROUND;

int THEME_BACKGROUND;

int LAYOUT_NEEDED;

int LAYOUT_CHANGED;

int LAYOUT_CHILD;

int RELEASED;

int DISPOSE_SENT;

int FOREIGN_HANDLE;

int DRAG_DETECT;

int DEFAULT_WIDTH;

int DEFAULT_HEIGHT;

int ACTIVATE;

int BUTTON_PRESS_EVENT;

int BUTTON_PRESS_EVENT_INVERSE;

int BUTTON_RELEASE_EVENT;

int BUTTON_RELEASE_EVENT_INVERSE;

int CHANGED;

int CHANGE_VALUE;

int CLICKED;

int COMMIT;

int CONFIGURE_EVENT;

int DELETE_EVENT;

int DELETE_RANGE;

int DELETE_TEXT;

int ENTER_NOTIFY_EVENT;

int EVENT;

int EVENT_AFTER;

int EXPAND_COLLAPSE_CURSOR_ROW;

int EXPOSE_EVENT;

int EXPOSE_EVENT_INVERSE;

int FOCUS;

int FOCUS_IN_EVENT;

int FOCUS_OUT_EVENT;

int GRAB_FOCUS;

int HIDE;

int INPUT;

int INSERT_TEXT;

int KEY_PRESS_EVENT;

int KEY_RELEASE_EVENT;

int LEAVE_NOTIFY_EVENT;

int MAP;

int MAP_EVENT;

int MNEMONIC_ACTIVATE;

int MOTION_NOTIFY_EVENT;

int MOTION_NOTIFY_EVENT_INVERSE;

int MOVE_FOCUS;

int OUTPUT;

int POPULATE_POPUP;

int POPUP_MENU;

int PREEDIT_CHANGED;

int REALIZE;

int ROW_ACTIVATED;

int SCROLL_CHILD;

int SCROLL_EVENT;

int SELECT;

int SHOW;

int SHOW_HELP;

int SIZE_ALLOCATE;

int STYLE_SET;

int SWITCH_PAGE;

int TEST_COLLAPSE_ROW;

int TEST_EXPAND_ROW;

int TEXT_BUFFER_INSERT_TEXT;

int TOGGLED;

int UNMAP;

int UNMAP_EVENT;

int UNREALIZE;

int VALUE_CHANGED;

int VISIBILITY_NOTIFY_EVENT;

int WINDOW_STATE_EVENT;

int ACTIVATE_INVERSE;

int DAY_SELECTED;

int MONTH_CHANGED;

int LAST_SIGNAL;

this();

this(Widget parent, int style);

void addListener(int eventType, Listener listener);

void addDisposeListener(DisposeListener listener);

void checkParent(Widget parent);

void checkSubclass();

void checkWidget();

void dispose();

Object getData();

Object getData(String key);

Display getDisplay();

Listener[] getListeners(int eventType);

int getStyle();

bool isDisposed();

bool isListening(int eventType);

void notifyListeners(int eventType, Event event);

void removeListener(int eventType, Listener handler);

void removeListener(int eventType, SWTEventListener handler);

void removeDisposeListener(DisposeListener listener);

void setData(Object data);

void setData(String key, Object value);

String toString();

}

Constructors

this this(): Prevents uninitialized instances from being created outside the package.
this this(Widget parent, int style): Constructs a new instance of this class given its parent and a style value describing its behavior and appearance. 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 bitwise OR'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.

Members

Functions

addDisposeListener void addDisposeListener(DisposeListener listener): 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.
addListener void addListener(int eventType, Listener listener): 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>.
checkParent void checkParent(Widget parent): Throws an exception if the specified widget can not be used as a parent for the receiver.
checkSubclass void checkSubclass(): Checks that this class can be subclassed. 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. IMPORTANT: 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. 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.
checkWidget void checkWidget(): 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 should be called by widget implementors to enforce the standard SWT invariants. 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. In future releases of SWT, there may be more or fewer error checks and exceptions may be thrown for different reasons.
dispose void dispose(): Disposes of the operating system resources associated with the receiver and all its descendants. After this method has been invoked, the receiver and all descendants 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. NOTE: This method is not called recursively on the descendants 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.
getData Object getData(): Returns the application defined widget data associated with the receiver, or null if it has not been set. The widget data is a single, unnamed field that is stored with every widget. 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.
getData Object getData(String key): Returns the application defined property of the receiver with the specified name, or null if it has not been set. 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.
getDisplay Display getDisplay(): Returns the <code>Display</code> that is associated with the receiver. 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.
getListeners Listener[] getListeners(int eventType): 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>.
getStyle int getStyle(): Returns the receiver's style information. Note that the value which is returned by this method may not match 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.
isDisposed bool isDisposed(): Returns <code>true</code> if the widget has been disposed, and <code>false</code> otherwise. 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.
isListening bool isListening(int eventType): 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>.
notifyListeners void notifyListeners(int eventType, Event event): 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>.
removeDisposeListener void removeDisposeListener(DisposeListener listener): Removes the listener from the collection of listeners who will be notified when the widget is disposed.
removeListener void removeListener(int eventType, Listener handler): 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>.
removeListener void removeListener(int eventType, SWTEventListener handler): Removes the listener from the collection of listeners who will be notified when an event of the given type occurs. IMPORTANT: This method is not part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It should never be referenced from application code.
setData void setData(Object data): Sets the application defined widget data associated with the receiver to be the argument. The widget data is a single, unnamed field that is stored with every widget. 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.
setData void setData(String key, Object value): Sets the application defined property of the receiver with the specified name to the given value. 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.
toString String toString(): Returns a string containing a concise, human-readable description of the receiver.

Variables

handle GtkWidget* handle;: the handle to the OS resource (Warning: This field is platform dependent) IMPORTANT: This field is not part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms and should never be accessed from application code.

Widget

Constructors

Members

Functions

Variables

Meta

Source