Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2011 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.widgets; import org.eclipse.swt.*; /** * This class is the abstract superclass of the classes * that represent the built in platform dialogs. * A <code>Dialog</code> typically contains other widgets * that are not accessible. A <code>Dialog</code> is not * a <code>Widget</code>. * <p> * This class can also be used as the abstract superclass * for user-designed dialogs. Such dialogs usually consist * of a Shell with child widgets. The basic template for a * user-defined dialog typically looks something like this:</p> * <pre><code> * public class MyDialog extends Dialog { * Object result; * * public MyDialog (Shell parent, int style) { * super (parent, style); * } * public MyDialog (Shell parent) { * this (parent, 0); // your default style bits go here (not the Shell's style bits) * } * public Object open () { * Shell parent = getParent(); * Shell shell = new Shell(parent, SWT.DIALOG_TRIM | SWT.APPLICATION_MODAL); * shell.setText(getText()); * // Your code goes here (widget creation, set result, etc). * shell.open(); * Display display = parent.getDisplay(); * while (!shell.isDisposed()) { * if (!display.readAndDispatch()) display.sleep(); * } * return result; * } * } * </code></pre> * <p> * Note: The <em>modality</em> styles supported by this class * are treated as <em>HINT</em>s, because not all are supported * by every subclass on every platform. If a modality style is * not supported, it is "upgraded" to a more restrictive modality * style that is supported. For example, if <code>PRIMARY_MODAL</code> * is not supported by a particular dialog, it would be upgraded to * <code>APPLICATION_MODAL</code>. In addition, as is the case * for shells, the window manager for the desktop on which the * instance is visible has ultimate control over the appearance * and behavior of the instance, including its modality. * </p> * <dl> * <dt><b>Styles:</b></dt> * <dd>APPLICATION_MODAL, PRIMARY_MODAL, SYSTEM_MODAL, SHEET</dd> * <dt><b>Events:</b></dt> * <dd>(none)</dd> * </dl> * <p> * Note: Only one of the styles APPLICATION_MODAL, PRIMARY_MODAL, * and SYSTEM_MODAL may be specified. * </p> * * @see Shell * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: ControlExample</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> */ public abstract class Dialog { int style; Shell parent; String title; /** * Constructs a new instance of this class given only its * parent. * * @param parent a shell which will be the parent of the new instance * * @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> * </ul> */ public Dialog(Shell parent) { this(parent, SWT.PRIMARY_MODAL); } /** * 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. * * @param parent a shell which will be the parent of the new instance * @param style the style of dialog 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> * </ul> * * @see SWT#PRIMARY_MODAL * @see SWT#APPLICATION_MODAL * @see SWT#SYSTEM_MODAL */ public Dialog(Shell parent, int style) { checkParent(parent); this.parent = parent; this.style = style; title = ""; } /** * Checks that this class can be subclassed. * <p> * IMPORTANT: See the comment in <code>Widget.checkSubclass()</code>. * </p> * * @exception SWTException <ul> * <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li> * </ul> * * @see Widget#checkSubclass */ protected void checkSubclass() { if (!Display.isValidClass(getClass())) { error(SWT.ERROR_INVALID_SUBCLASS); } } /** * Throws an exception if the specified widget can not be * used as a parent for the receiver. * * @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> * </ul> */ void checkParent(Shell parent) { if (parent == null) error(SWT.ERROR_NULL_ARGUMENT); parent.checkWidget(); } static int checkStyle(Shell parent, int style) { int mask = SWT.PRIMARY_MODAL | SWT.APPLICATION_MODAL | SWT.SYSTEM_MODAL; if ((style & SWT.SHEET) != 0) { style &= ~SWT.SHEET; if ((style & mask) == 0) { style |= parent == null ? SWT.APPLICATION_MODAL : SWT.PRIMARY_MODAL; } } if ((style & mask) == 0) { style |= SWT.APPLICATION_MODAL; } 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; } } return Widget.checkBits(style, SWT.LEFT_TO_RIGHT, SWT.RIGHT_TO_LEFT, 0, 0, 0, 0); } /** * Does whatever dialog specific cleanup is required, and then * uses the code in <code>SWTError.error</code> to handle the error. * * @param code the descriptive error code * * @see SWT#error(int) */ void error(int code) { SWT.error(code); } /** * Returns the receiver's parent, which must be a <code>Shell</code> * or null. * * @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 Shell getParent() { return parent; } /** * 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. * </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() { return style; } /** * Returns the receiver's text, which is the string that the * window manager will typically display as the receiver's * <em>title</em>. If the text has not previously been set, * returns an empty string. * * @return the text * * @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 String getText() { return title; } /** * Sets the receiver's text, which is the string that the * window manager will typically display as the receiver's * <em>title</em>, to the argument, which must not be null. * * @param string the new text * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the text 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> */ public void setText(String string) { if (string == null) error(SWT.ERROR_NULL_ARGUMENT); title = string; } }