Java tutorial
/******************************************************************************* * Copyright (c) 2002, 2015 Innoopract Informationssysteme GmbH and others. * 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.rap.rwt.internal.lifecycle.WidgetLCA; import org.eclipse.swt.SWT; import org.eclipse.swt.SWTException; import org.eclipse.swt.events.ArmListener; import org.eclipse.swt.events.DisposeEvent; import org.eclipse.swt.events.DisposeListener; import org.eclipse.swt.events.HelpListener; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.events.SelectionListener; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.internal.widgets.IItemHolderAdapter; import org.eclipse.swt.internal.widgets.menuitemkit.MenuItemLCA; /** * Instances of this class represent a selectable user interface object * that issues notification when pressed and released. * <dl> * <dt><b>Styles:</b></dt> * <dd>CHECK, CASCADE, PUSH, RADIO, SEPARATOR</dd> * <dt><b>Events:</b></dt> * <dd>Arm, Help, Selection</dd> * </dl> * <p> * Note: Only one of the styles CHECK, CASCADE, PUSH, RADIO and SEPARATOR * may be specified. * </p><p> * IMPORTANT: This class is <em>not</em> intended to be subclassed. * </p> */ public class MenuItem extends Item { private final Menu parent; private Menu menu; private DisposeListener menuDisposeListener; private boolean selection; private int userId; private AcceleratorBinding acceleratorBinding; /** * Constructs a new instance of this class given its parent * (which must be a <code>Menu</code>) and a style value * describing its behavior and appearance. The item is added * to the end of the items maintained by its parent. * <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 menu control which will be the parent of the new instance (cannot be null) * @param style the style of control to construct * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the parent is null</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#CHECK * @see SWT#CASCADE * @see SWT#PUSH * @see SWT#RADIO * @see SWT#SEPARATOR * @see Widget#checkSubclass * @see Widget#getStyle */ public MenuItem(Menu parent, int style) { super(parent, checkStyle(style)); this.parent = parent; parent.getAdapter(IItemHolderAdapter.class).add(this); } /** * Constructs a new instance of this class given its parent * (which must be a <code>Menu</code>), a style value * describing its behavior and appearance, and the index * at which to place it in the items maintained by its parent. * <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 menu control which will be the parent of the new instance (cannot be null) * @param style the style of control to construct * @param index the zero-relative index to store the receiver in its parent * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the parent is null</li> * <li>ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the parent (inclusive)</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#CHECK * @see SWT#CASCADE * @see SWT#PUSH * @see SWT#RADIO * @see SWT#SEPARATOR * @see Widget#checkSubclass * @see Widget#getStyle */ public MenuItem(Menu parent, int style, int index) { super(parent, checkStyle(style)); this.parent = parent; parent.getAdapter(IItemHolderAdapter.class).insert(this, index); } /** * Returns the receiver's parent, which must be a <code>Menu</code>. * * @return the receiver's parent * * @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 Menu getParent() { checkWidget(); return parent; } /** * Sets the receiver's pull down menu to the argument. * Only <code>CASCADE</code> menu items can have a * pull down menu. The sequence of key strokes, button presses * and/or button releases that are used to request a pull down * menu is platform specific. * <p> * Note: Disposing of a menu item that has a pull down menu * will dispose of the menu. To avoid this behavior, set the * menu to null before the menu item is disposed. * </p> * * @param menu the new pull down menu * * @exception IllegalArgumentException <ul> * <li>ERROR_MENU_NOT_DROP_DOWN - if the menu is not a drop down menu</li> * <li>ERROR_MENUITEM_NOT_CASCADE - if the menu item is not a <code>CASCADE</code></li> * <li>ERROR_INVALID_ARGUMENT - if the menu has been disposed</li> * <li>ERROR_INVALID_PARENT - if the menu is not in the same widget tree</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> */ public void setMenu(Menu menu) { checkWidget(); if (this.menu != menu) { if ((style & SWT.CASCADE) == 0) { SWT.error(SWT.ERROR_MENUITEM_NOT_CASCADE); } if (menu != null) { if (menu.isDisposed()) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } if ((menu.getStyle() & SWT.DROP_DOWN) == 0) { SWT.error(SWT.ERROR_MENU_NOT_DROP_DOWN); } if (menu.getParent() != getParent().getParent()) { SWT.error(SWT.ERROR_INVALID_PARENT); } } removeMenuDisposeListener(); /* Assign the new menu */ if (this.menu != null) { this.menu.cascade = null; } this.menu = menu; if (menu != null) { menu.cascade = this; } addMenuDisposeListener(); } } /** * Returns the receiver's cascade menu if it has one or null * if it does not. Only <code>CASCADE</code> menu items can have * a pull down menu. The sequence of key strokes, button presses * and/or button releases that are used to request a pull down * menu is platform specific. * * @return the receiver's menu * * @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 Menu getMenu() { checkWidget(); return menu; } /** * Sets the identifier associated with the receiver to the argument. * * @param id the new identifier. This must be a non-negative value. System-defined identifiers are negative values. * * @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> * <li>ERROR_INVALID_ARGUMENT - if called with an negative-valued argument.</li> * </ul> * * @since 1.4 */ public void setID(int id) { checkWidget(); if (id < 0) { error(SWT.ERROR_INVALID_ARGUMENT); } userId = id; } /** * Gets the identifier associated with the receiver. * * @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 1.4 */ public int getID() { checkWidget(); return userId; } /** * Sets the image the receiver will display to the argument. * <p> * Note: This operation is a hint and is not supported on * platforms that do not have this concept (for example, Windows NT). * </p> * * @param image the image to display * * @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> */ @Override public void setImage(Image image) { checkWidget(); if ((style & SWT.SEPARATOR) == 0) { super.setImage(image); } } /** * Sets the widget accelerator. An accelerator is the bit-wise * OR of zero or more modifier masks and a key. Examples: * <code>SWT.MOD1 | SWT.MOD2 | 'T', SWT.MOD3 | SWT.F2</code>. * <code>SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2</code>. * The default value is zero, indicating that the menu item does * not have an accelerator. * * @param accelerator an integer that is the bit-wise OR of masks and a key * * </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> * * @since 2.1 */ public void setAccelerator(int accelerator) { checkWidget(); if (accelerator != 0) { if (acceleratorBinding == null) { acceleratorBinding = new AcceleratorBinding(this); } acceleratorBinding.setAccelerator(accelerator); } else if (acceleratorBinding != null) { acceleratorBinding.release(); acceleratorBinding = null; } } /** * Returns the widget accelerator. An accelerator is the bit-wise * OR of zero or more modifier masks and a key. Examples: * <code>SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2</code>. * The default value is zero, indicating that the menu item does * not have an accelerator. * * @return the accelerator or 0 * * </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> * * @since 2.1 */ public int getAccelerator() { checkWidget(); return acceleratorBinding != null ? acceleratorBinding.getAccelerator() : 0; } ////////// // Enabled /** * Enables the receiver if the argument is <code>true</code>, * and disables it otherwise. A disabled menu item is typically * not selectable from the user interface and draws with an * inactive or "grayed" look. * * @param enabled the new enabled state * * @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 void setEnabled(boolean enabled) { checkWidget(); removeState(DISABLED); if (!enabled) { addState(DISABLED); } } /** * Returns <code>true</code> if the receiver is enabled, and * <code>false</code> otherwise. A disabled menu item is typically * not selectable from the user interface and draws with an * inactive or "grayed" look. * * @return the receiver's enabled state * * @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 #isEnabled */ public boolean getEnabled() { checkWidget(); return !hasState(DISABLED); } /** * Returns <code>true</code> if the receiver is enabled and all * of the receiver's ancestors are enabled, and <code>false</code> * otherwise. A disabled menu item is typically not selectable from the * user interface and draws with an inactive or "grayed" look. * * @return the receiver's enabled state * * @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 #getEnabled */ public boolean isEnabled() { return getEnabled() && parent.isEnabled(); } //////////// // Selection /** * Returns <code>true</code> if the receiver is selected, * and false otherwise. * <p> * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>, * it is selected when it is checked. * * @return the selection state * * @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 boolean getSelection() { checkWidget(); return selection; } /** * Sets the selection state of the receiver. * <p> * When the receiver is of type <code>CHECK</code> or <code>RADIO</code>, * it is selected when it is checked. * * @param selection the new selection state * * @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 void setSelection(boolean selection) { checkWidget(); if ((style & (SWT.CHECK | SWT.RADIO)) != 0) { this.selection = selection; } } /////////////////////// // Listener maintenance /** * Adds the listener to the collection of listeners who will * be notified when the menu item is selected, by sending * it one of the messages defined in the <code>SelectionListener</code> * interface. * <p> * When <code>widgetSelected</code> is called, the stateMask field of the event object is valid. * <code>widgetDefaultSelected</code> is not called. * </p> * * @param listener the listener which should be notified * * @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 SelectionListener * @see #removeSelectionListener * @see SelectionEvent */ public void addSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) { SWT.error(SWT.ERROR_NULL_ARGUMENT); } TypedListener typedListener = new TypedListener(listener); addListener(SWT.Selection, typedListener); addListener(SWT.DefaultSelection, typedListener); } /** * Removes the listener from the collection of listeners who will * be notified when the control is selected. * * @param listener the listener which should no longer be notified * * @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 SelectionListener * @see #addSelectionListener */ public void removeSelectionListener(SelectionListener listener) { checkWidget(); if (listener == null) { SWT.error(SWT.ERROR_NULL_ARGUMENT); } removeListener(SWT.Selection, listener); removeListener(SWT.DefaultSelection, listener); } /** * Adds the listener to the collection of listeners who will * be notified when the help events are generated for the control, by sending * it one of the messages defined in the <code>HelpListener</code> * interface. * * @param listener the listener which should be notified * * @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 HelpListener * @see #removeHelpListener * @since 1.3 */ public void addHelpListener(HelpListener listener) { checkWidget(); if (listener == null) { error(SWT.ERROR_NULL_ARGUMENT); } TypedListener typedListener = new TypedListener(listener); addListener(SWT.Help, typedListener); } /** * Removes the listener from the collection of listeners who will * be notified when the help events are generated for the control. * * @param listener the listener which should no longer be notified * * @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 HelpListener * @see #addHelpListener * @since 1.3 */ public void removeHelpListener(HelpListener listener) { checkWidget(); if (listener == null) { error(SWT.ERROR_NULL_ARGUMENT); } removeListener(SWT.Help, listener); } /** * Adds the listener to the collection of listeners who will * be notified when the arm events are generated for the control, by sending * it one of the messages defined in the <code>ArmListener</code> * interface. * * @param listener the listener which should be notified * * @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 ArmListener * @see #removeArmListener * @since 1.3 */ public void addArmListener(ArmListener listener) { checkWidget(); if (listener == null) { error(SWT.ERROR_NULL_ARGUMENT); } TypedListener typedListener = new TypedListener(listener); addListener(SWT.Arm, typedListener); } /** * Removes the listener from the collection of listeners who will * be notified when the arm events are generated for the control. * * @param listener the listener which should no longer be notified * * @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 ArmListener * @see #addArmListener * @since 1.3 */ public void removeArmListener(ArmListener listener) { checkWidget(); removeListener(SWT.Arm, listener); } @Override @SuppressWarnings("unchecked") public <T> T getAdapter(Class<T> adapter) { if (adapter == WidgetLCA.class) { return (T) MenuItemLCA.INSTANCE; } return super.getAdapter(adapter); } ////////////////// // Item overrides @Override void releaseWidget() { super.releaseWidget(); if (acceleratorBinding != null) { acceleratorBinding.release(); acceleratorBinding = null; } } @Override final void releaseChildren() { if (menu != null) { removeMenuDisposeListener(); menu.dispose(); menu = null; } } @Override final void releaseParent() { super.releaseParent(); parent.getAdapter(IItemHolderAdapter.class).remove(this); } @Override String getNameText() { String result; if ((style & SWT.SEPARATOR) != 0) { result = "|"; } else { result = super.getNameText(); } return result; } /////////////////////////////////////////////////////// // Helping methods to observe the disposal of the menu private void addMenuDisposeListener() { if (menu != null) { if (menuDisposeListener == null) { menuDisposeListener = new DisposeListener() { @Override public void widgetDisposed(DisposeEvent event) { menu = null; } }; } menu.addDisposeListener(menuDisposeListener); } } private void removeMenuDisposeListener() { if (menu != null) { menu.removeDisposeListener(menuDisposeListener); } } void handleAcceleratorActivation() { if ((style & SWT.CHECK) != 0) { selection = !selection; } else if ((style & SWT.RADIO) != 0) { deselectOtherRadios(); selection = true; } notifyListeners(SWT.Selection, new Event()); } private void deselectOtherRadios() { for (MenuItem item : parent.getItems()) { if (item != this && (item.getStyle() & SWT.RADIO) != 0 && item.getSelection()) { item.setSelection(false); item.notifyListeners(SWT.Selection, new Event()); } } } /////////////////////////////////////// // Helping methods to verify arguments private static int checkStyle(int style) { return checkBits(style, SWT.PUSH, SWT.CHECK, SWT.RADIO, SWT.SEPARATOR, SWT.CASCADE, 0); } /////////////////// // Skinning support @Override void reskinChildren(int flags) { if (menu != null) { menu.reskin(flags); } super.reskinChildren(flags); } }