Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2015 IBM Corporation 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: * IBM Corporation - initial API and implementation * Stefan Xenos, IBM - bug 156790: Adopt GridLayoutFactory within JFace *******************************************************************************/ package org.eclipse.jface.dialogs; import org.eclipse.core.runtime.Assert; import org.eclipse.jface.layout.GridDataFactory; import org.eclipse.jface.layout.GridLayoutFactory; import org.eclipse.jface.layout.LayoutConstants; import org.eclipse.jface.resource.JFaceResources; import org.eclipse.swt.SWT; import org.eclipse.swt.accessibility.AccessibleAdapter; import org.eclipse.swt.accessibility.AccessibleEvent; import org.eclipse.swt.graphics.Image; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.Control; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Label; import org.eclipse.swt.widgets.Shell; /** * The IconAndMessageDialog is the abstract superclass of dialogs that have an * icon and a message as the first two widgets. In this dialog the icon and * message are direct children of the shell in order that they can be read by * accessibility tools more easily. * <p> * <strong>Note:</strong> Clients are expected to call {@link #createMessageArea(Composite)}, * otherwise neither the icon nor the message will appear. * </p> */ public abstract class IconAndMessageDialog extends Dialog { /** * Message (a localized string). */ protected String message; /** * Message label is the label the message is shown on. */ protected Label messageLabel; /** * Return the label for the image. */ protected Label imageLabel; /** * Constructor for IconAndMessageDialog. * * @param parentShell * the parent shell, or <code>null</code> to create a top-level * shell */ public IconAndMessageDialog(Shell parentShell) { super(parentShell); } /** * Create the area the message will be shown in. * <p> * The parent composite is assumed to use GridLayout as its layout manager, * since the parent is typically the composite created in * {@link Dialog#createDialogArea}. * </p> * <p> * <strong>Note:</strong> Clients are expected to call this method, otherwise * neither the icon nor the message will appear. * </p> * * @param composite * The composite to parent from. * @return Control */ protected Control createMessageArea(Composite composite) { // create composite // create image Image image = getImage(); if (image != null) { imageLabel = new Label(composite, SWT.NULL); image.setBackground(imageLabel.getBackground()); imageLabel.setImage(image); addAccessibleListeners(imageLabel, image); GridDataFactory.fillDefaults().align(SWT.CENTER, SWT.BEGINNING).applyTo(imageLabel); } // create message if (message != null) { messageLabel = new Label(composite, getMessageLabelStyle()); messageLabel.setText(message); GridDataFactory.fillDefaults().align(SWT.FILL, SWT.BEGINNING).grab(true, false) .hint(convertHorizontalDLUsToPixels(IDialogConstants.MINIMUM_MESSAGE_AREA_WIDTH), SWT.DEFAULT) .applyTo(messageLabel); } return composite; } private String getAccessibleMessageFor(Image image) { if (image.equals(getErrorImage())) { return JFaceResources.getString("error");//$NON-NLS-1$ } if (image.equals(getWarningImage())) { return JFaceResources.getString("warning");//$NON-NLS-1$ } if (image.equals(getInfoImage())) { return JFaceResources.getString("info");//$NON-NLS-1$ } if (image.equals(getQuestionImage())) { return JFaceResources.getString("question"); //$NON-NLS-1$ } return null; } /** * Add an accessible listener to the label if it can be inferred from the * image. * * @param label * @param image */ private void addAccessibleListeners(Label label, final Image image) { label.getAccessible().addAccessibleListener(new AccessibleAdapter() { @Override public void getName(AccessibleEvent event) { final String accessibleMessage = getAccessibleMessageFor(image); if (accessibleMessage == null) { return; } event.result = accessibleMessage; } }); } /** * Returns the style for the message label. * * @return the style for the message label * * @since 3.0 */ protected int getMessageLabelStyle() { return SWT.WRAP; } /* * @see Dialog.createButtonBar() */ @Override protected Control createButtonBar(Composite parent) { Composite composite = new Composite(parent, SWT.NONE); GridLayoutFactory.fillDefaults().numColumns(0) // this is incremented // by createButton .equalWidth(true).applyTo(composite); GridDataFactory.fillDefaults().align(SWT.END, SWT.CENTER).span(2, 1).applyTo(composite); composite.setFont(parent.getFont()); // Add the buttons to the button bar. createButtonsForButtonBar(composite); return composite; } /** * Returns the image to display beside the message in this dialog. * <p> * Subclasses may override. * </p> * * @return the image to display beside the message * @since 2.0 */ protected abstract Image getImage(); /* * @see Dialog.createContents(Composite) */ @Override protected Control createContents(Composite parent) { // initialize the dialog units initializeDialogUnits(parent); Point defaultSpacing = LayoutConstants.getSpacing(); GridLayoutFactory.fillDefaults().margins(LayoutConstants.getMargins()) .spacing(defaultSpacing.x * 2, defaultSpacing.y).numColumns(getColumnCount()).applyTo(parent); GridDataFactory.fillDefaults().grab(true, true).applyTo(parent); createDialogAndButtonArea(parent); return parent; } /** * Get the number of columns in the layout of the Shell of the dialog. * * @return int * @since 3.3 */ int getColumnCount() { return 2; } /** * Create the dialog area and the button bar for the receiver. * * @param parent */ protected void createDialogAndButtonArea(Composite parent) { // create the dialog area and button bar dialogArea = createDialogArea(parent); buttonBar = createButtonBar(parent); // Apply to the parent so that the message gets it too. applyDialogFont(parent); } /** * Return the <code>Image</code> to be used when displaying an error. * * @return image the error image */ public Image getErrorImage() { return getSWTImage(SWT.ICON_ERROR); } /** * Return the <code>Image</code> to be used when displaying a warning. * * @return image the warning image */ public Image getWarningImage() { return getSWTImage(SWT.ICON_WARNING); } /** * Return the <code>Image</code> to be used when displaying information. * * @return image the information image */ public Image getInfoImage() { return getSWTImage(SWT.ICON_INFORMATION); } /** * Return the <code>Image</code> to be used when displaying a question. * * @return image the question image */ public Image getQuestionImage() { return getSWTImage(SWT.ICON_QUESTION); } /** * Get an <code>Image</code> from the provide SWT image constant. * * @param imageID * the SWT image constant * @return image the image */ private Image getSWTImage(final int imageID) { Shell shell = getShell(); final Display display; if (shell == null || shell.isDisposed()) { shell = getParentShell(); } if (shell == null || shell.isDisposed()) { display = Display.getCurrent(); // The dialog should be always instantiated in UI thread. // However it was possible to instantiate it in other threads // (the code worked in most cases) so the assertion covers // only the failing scenario. See bug 107082 for details. Assert.isNotNull(display, "The dialog should be created in UI thread"); //$NON-NLS-1$ } else { display = shell.getDisplay(); } final Image[] image = new Image[1]; display.syncExec(() -> image[0] = display.getSystemImage(imageID)); return image[0]; } }