org.eclipse.swt.snippets.Snippet363.java Source code

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Here is the source code for org.eclipse.swt.snippets.Snippet363.java

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/*******************************************************************************
 * Copyright (c) 2012, 2016 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.snippets;

/*
 * Accessibility example snippet: Declare a message area to be a "live region",
 * and send "changed" events to a screen reader when the message area is updated.
 * Note: This snippet will only work with Windows screen readers.
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.swt.*;
import org.eclipse.swt.accessibility.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class Snippet363 {
    static final String errorMessage = "Error: Number expected.";
    static Label icon;
    static Image errorIcon;
    static Text liveLabel;

    public static void main(String[] args) {
        Display display = new Display();
        errorIcon = display.getSystemImage(SWT.ICON_ERROR);
        Shell shell = new Shell(display);
        shell.setText("Snippet 363");
        shell.setLayout(new GridLayout(2, false));
        shell.setText("LiveRegion Test");

        icon = new Label(shell, SWT.NONE);
        icon.setLayoutData(new GridData(32, 32));

        liveLabel = new Text(shell, SWT.READ_ONLY);
        GC gc = new GC(liveLabel);
        Point pt = gc.textExtent(errorMessage);
        GridData data = new GridData(SWT.FILL, SWT.CENTER, true, false);
        data.minimumWidth = (int) (pt.x + gc.getFontMetrics().getAverageCharacterWidth() * 2);
        gc.dispose();
        liveLabel.setLayoutData(data);
        liveLabel.setText("");
        liveLabel.getAccessible().addAccessibleAttributeListener(new AccessibleAttributeAdapter() {
            @Override
            public void getAttributes(AccessibleAttributeEvent e) {
                e.attributes = new String[] { "container-live", "polite", "live", "polite", "container-live-role",
                        "status", };
            }
        });

        final Label textFieldLabel = new Label(shell, SWT.NONE);
        textFieldLabel.setText("Type a number:");
        textFieldLabel.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 2, 1));

        final Text textField = new Text(shell, SWT.SINGLE | SWT.BORDER);
        textField.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 2, 1));

        final Button okButton = new Button(shell, SWT.PUSH);
        okButton.setText("OK");
        okButton.setLayoutData(new GridData(SWT.END, SWT.CENTER, false, false, 2, 1));
        okButton.setEnabled(false);

        textField.addModifyListener(e -> {
            boolean isNumber = false;
            String textValue = textField.getText();
            try {
                Integer.parseInt(textValue);
                isNumber = true;
                setMessageText(false, "Thank-you");
            } catch (NumberFormatException ex) {
                if (textValue.isEmpty()) {
                    setMessageText(false, "");
                } else {
                    setMessageText(true, "Error: Number expected.");
                }
            }
            okButton.setEnabled(isNumber);
        });

        textField.setFocus();
        shell.pack();
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        display.dispose();
    }

    static void setMessageText(boolean error, String newMessage) {
        String oldMessage = liveLabel.getText();
        icon.setImage(error ? errorIcon : null);
        liveLabel.setText(newMessage);
        liveLabel.getAccessible().sendEvent(ACC.EVENT_ATTRIBUTE_CHANGED, null);
        liveLabel.getAccessible().sendEvent(ACC.EVENT_TEXT_CHANGED,
                new Object[] { ACC.TEXT_DELETE, 0, oldMessage.length(), oldMessage });
        liveLabel.getAccessible().sendEvent(ACC.EVENT_TEXT_CHANGED,
                new Object[] { ACC.TEXT_INSERT, 0, newMessage.length(), newMessage });
    }

}