Java tutorial
/******************************************************************************* * Copyright (c) 2012 Arapiki Solutions Inc. * 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: * "Peter Smith <psmith@arapiki.com>" - initial API and * implementation and/or initial documentation *******************************************************************************/ package com.buildml.eclipse.utils; import org.eclipse.jface.dialogs.IDialogConstants; import org.eclipse.jface.dialogs.IMessageProvider; import org.eclipse.jface.dialogs.TitleAreaDialog; import org.eclipse.swt.SWT; import org.eclipse.swt.custom.ScrolledComposite; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Label; /** * A general purpose dialog box for reporting information, warnings and errors to the * end user. * * @author "Peter Smith <psmith@arapiki.com>" */ public class AlertDialog extends TitleAreaDialog { /*=====================================================================================* * FIELDS/TYPES *=====================================================================================*/ /** Maximum size of a dialog box is 1/MAX_DIALOG_RATIO of the screen height/width */ private static final int MAX_DIALOG_RATIO = 2; /** The title of the dialog box */ private String title; /** The detailed message to display */ private String message; /** The severity level */ private int severity; /** Should the dialog box provide a "cancel" choice? */ private boolean allowCancel; /*=====================================================================================* * CONSTRUCTORS *=====================================================================================*/ /** * Create a new AlertDialog. This method is private, so can only be invoked by * the static class methods (displayInfoDialog, displayErrorDialog, etc). * @param title The title to display in the dialog box. * @param message The detailed message to display in the dialog box. * @param severity The severity level (e.g. IMessageProvider.ERROR). * @param allowCancel Should the dialog provide a "cancel" option? */ private AlertDialog(String title, String message, int severity, boolean allowCancel) { super(Display.getDefault().getActiveShell()); this.title = title; this.message = message; this.severity = severity; this.allowCancel = allowCancel; /* set the title image to say "BuildML" */ Image iconImage = EclipsePartUtils.getImage("images/buildml_logo_dialog.gif"); if (iconImage != null) { setTitleImage(iconImage); } } /*=====================================================================================* * PUBLIC METHODS *=====================================================================================*/ /** * Display an informational dialog box in the context of the current shell. Both * a general message and an explanatory reason will be display. Given that there's * only an "OK" button, there's no return code needed. * @param title The general informational message to be displayed. * @param message The detailed reason for the event. */ public static void displayInfoDialog(String title, String message) { openDialog(title, message, IMessageProvider.INFORMATION, false); } /*-------------------------------------------------------------------------------------*/ /** * Display an warning dialog box in the context of the current shell. Both * a general message and an explanatory reason will be display. Given that there's * only an "OK" button, there's no return code needed. * @param title The general informational message to be displayed. * @param message The detailed reason for the event. */ public static void displayWarningDialog(String title, String message) { openDialog(title, message, IMessageProvider.WARNING, false); } /*-------------------------------------------------------------------------------------*/ /** * Display an error dialog box in the context of the current shell. Both * a general message and an explanatory reason will be display. Given that there's * only an "OK" button, there's no return code needed. * @param title The general error message to be displayed. * @param message The detailed reason for the event. */ public static void displayErrorDialog(final String title, final String message) { openDialog(title, message, IMessageProvider.ERROR, false); } /*-------------------------------------------------------------------------------------*/ /** * Display an question dialog box in the context of the current shell. The user will * be expected to click on OK or CANCEL to answer the question. * @param message The question to be displayed. * @return The answer to the question (IDialogConstants.OK_ID or IDialogConstants.CANCEL_ID). */ public static int displayOKCancelDialog(final String message) { return openDialog("Question...", message, IMessageProvider.INFORMATION, true); } /*=====================================================================================* * PROTECTED METHODS *=====================================================================================*/ /* (non-Javadoc) * @see org.eclipse.jface.dialogs.Dialog#createDialogArea(org.eclipse.swt.widgets.Composite) */ @Override protected Control createDialogArea(Composite parent) { /* set the dialog's title, or default to "Alert" */ setHelpAvailable(false); if (title == null) { title = "Alert"; } setMessage(title, severity); /* create and format the top-level composite of this dialog */ Composite composite = (Composite) super.createDialogArea(parent); composite.setLayout(new GridLayout()); GridData gd = new GridData(SWT.FILL, SWT.FILL, true, true); composite.setLayoutData(gd); ScrolledComposite sc = new ScrolledComposite(composite, SWT.V_SCROLL | SWT.H_SCROLL); sc.setLayout(new GridLayout()); sc.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true)); /* create a label for the message, and centre it */ if (message != null) { Label label = new Label(sc, SWT.WRAP); label.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true)); label.setText(message); sc.setContent(label); label.setSize(label.computeSize(SWT.DEFAULT, SWT.DEFAULT)); } return parent; } /*-------------------------------------------------------------------------------------*/ /* (non-Javadoc) * @see org.eclipse.jface.dialogs.Dialog#createButton(org.eclipse.swt.widgets.Composite, * int, java.lang.String, boolean) */ @Override protected Button createButton(Composite parent, int id, String label, boolean defaultButton) { /* * Ignore the CANCEL button (if not needed), but display the OK button. */ if (!allowCancel && (id == IDialogConstants.CANCEL_ID)) { return null; } else { return super.createButton(parent, id, label, defaultButton); } } /*-------------------------------------------------------------------------------------*/ /** * When the dialog box is created (based on the size of all the child widgets - particularly * the label), make sure that it never takes up too much of the screen, otherwise it loses * the feeling of being a Dialog. */ @Override protected Point getInitialSize() { Point initialSize = super.getInitialSize(); int screenWidth = EclipsePartUtils.getScreenWidth(); int screenHeight = EclipsePartUtils.getScreenHeight(); if (initialSize.x > (screenWidth / MAX_DIALOG_RATIO)) { initialSize.x = screenWidth / MAX_DIALOG_RATIO; } if (initialSize.y > (screenHeight / MAX_DIALOG_RATIO)) { initialSize.y = screenHeight / MAX_DIALOG_RATIO; } return initialSize; } /*=====================================================================================* * PRIVATE METHODS *=====================================================================================*/ /** * Create and open a dialog box, using the UI thread. This allows non-UI code to * raise an error. * * @param title The title to display in the dialog box. * @param message The detailed message to display in the dialog box. * @param severity The severity level (e.g. IMessageProvider.ERROR). * @param allowCancel Should the dialog provide a "cancel" option? * @return The dialog status (typically IDialogConstants.OK_ID or * IDialogConstants.CANCEL_ID). */ private static int openDialog(final String title, final String message, final int severity, final boolean allowCancel) { /* for returning the dialog code (OK/Cancel/etc) from the UI thread */ final Integer retCode[] = new Integer[1]; /* Open the dialog in the UI thread, blocking until the user presses "OK" */ Display.getDefault().syncExec(new Runnable() { public void run() { AlertDialog dialog = new AlertDialog(title, message, severity, allowCancel); dialog.setBlockOnOpen(true); dialog.open(); /* return response back to our calling thread */ retCode[0] = dialog.getReturnCode(); } }); /* status code? (OK, Cancel, etc) */ return retCode[0]; } /*-------------------------------------------------------------------------------------*/ }