org.eclipse.swt.examples.javaviewer.JavaViewer.java Source code

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Here is the source code for org.eclipse.swt.examples.javaviewer.JavaViewer.java

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/*******************************************************************************
 * Copyright (c) 2000, 2017 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.examples.javaviewer;

import static org.eclipse.swt.events.SelectionListener.widgetSelectedAdapter;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.text.MessageFormat;
import java.util.ResourceBundle;

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.ShellListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.MenuItem;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.widgets.Shell;

public class JavaViewer {
    Shell shell;
    StyledText text;
    JavaLineStyler lineStyler = new JavaLineStyler();
    FileDialog fileDialog;
    static ResourceBundle resources = ResourceBundle.getBundle("examples_javaviewer");

    Menu createFileMenu() {
        Menu bar = shell.getMenuBar();
        Menu menu = new Menu(bar);
        MenuItem item;

        // Open
        item = new MenuItem(menu, SWT.PUSH);
        item.setText(resources.getString("Open_menuitem"));
        item.setAccelerator(SWT.MOD1 + 'O');
        item.addSelectionListener(widgetSelectedAdapter(event -> openFile()));

        // Exit
        item = new MenuItem(menu, SWT.PUSH);
        item.setText(resources.getString("Exit_menuitem"));
        item.addSelectionListener(widgetSelectedAdapter(e -> menuFileExit()));
        return menu;
    }

    void createMenuBar() {
        Menu bar = new Menu(shell, SWT.BAR);
        shell.setMenuBar(bar);

        MenuItem fileItem = new MenuItem(bar, SWT.CASCADE);
        fileItem.setText(resources.getString("File_menuitem"));
        fileItem.setMenu(createFileMenu());

    }

    void createShell(Display display) {
        shell = new Shell(display);
        shell.setText(resources.getString("Window_title"));
        GridLayout layout = new GridLayout();
        layout.numColumns = 1;
        shell.setLayout(layout);
        shell.addShellListener(ShellListener.shellClosedAdapter(e -> {
            lineStyler.disposeColors();
            text.removeLineStyleListener(lineStyler);
        }));
    }

    void createStyledText() {
        text = new StyledText(shell, SWT.BORDER | SWT.MULTI | SWT.V_SCROLL | SWT.H_SCROLL);
        GridData spec = new GridData();
        spec.horizontalAlignment = GridData.FILL;
        spec.grabExcessHorizontalSpace = true;
        spec.verticalAlignment = GridData.FILL;
        spec.grabExcessVerticalSpace = true;
        text.setLayoutData(spec);
        text.addLineStyleListener(lineStyler);
        text.setEditable(false);
        Color bg = Display.getDefault().getSystemColor(SWT.COLOR_GRAY);
        text.setBackground(bg);
    }

    void displayError(String msg) {
        MessageBox box = new MessageBox(shell, SWT.ICON_ERROR);
        box.setMessage(msg);
        box.open();
    }

    public static void main(String[] args) {
        Display display = new Display();
        JavaViewer example = new JavaViewer();
        Shell shell = example.open(display);
        while (!shell.isDisposed())
            if (!display.readAndDispatch())
                display.sleep();
        display.dispose();
    }

    public Shell open(Display display) {
        createShell(display);
        createMenuBar();
        createStyledText();
        shell.setSize(500, 400);
        shell.open();
        return shell;
    }

    void openFile() {
        if (fileDialog == null) {
            fileDialog = new FileDialog(shell, SWT.OPEN);
        }

        fileDialog.setFilterExtensions(new String[] { "*.java", "*.*" });
        String name = fileDialog.open();

        open(name);
    }

    void open(String name) {
        final String textString;

        if ((name == null) || (name.length() == 0))
            return;

        File file = new File(name);
        if (!file.exists()) {
            String message = MessageFormat.format(resources.getString("Err_file_no_exist"), file.getName());
            displayError(message);
            return;
        }

        try {
            FileInputStream stream = new FileInputStream(file.getPath());
            try (Reader in = new BufferedReader(new InputStreamReader(stream))) {

                char[] readBuffer = new char[2048];
                StringBuilder buffer = new StringBuilder((int) file.length());
                int n;
                while ((n = in.read(readBuffer)) > 0) {
                    buffer.append(readBuffer, 0, n);
                }
                textString = buffer.toString();
                stream.close();
            } catch (IOException e) {
                // Err_file_io
                String message = MessageFormat.format(resources.getString("Err_file_io"), file.getName());
                displayError(message);
                return;
            }
        } catch (FileNotFoundException e) {
            String message = MessageFormat.format(resources.getString("Err_not_found"), file.getName());
            displayError(message);
            return;
        }
        // Guard against superfluous mouse move events -- defer action until later
        Display display = text.getDisplay();
        display.asyncExec(() -> text.setText(textString));

        // parse the block comments up front since block comments can go across
        // lines - inefficient way of doing this
        lineStyler.parseBlockComments(textString);
    }

    void menuFileExit() {
        shell.close();
    }
}