DrawingFrame.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.felix.example.extenderbased.host;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import org.apache.felix.example.extenderbased.host.extension.SimpleShape;

/**
 * This class represents the main application class, which is a JFrame subclass
 * that manages a toolbar of shapes and a drawing canvas. This class does not
 * directly interact with the underlying OSGi framework; instead, it is injected
 * with the available <tt>SimpleShape</tt> instances to eliminate any
 * dependencies on the OSGi application programming interfaces.
**/
public class DrawingFrame extends JFrame
    implements MouseListener, MouseMotionListener
{
    private static final long serialVersionUID = 1L;
    private static final int BOX = 54;
    private final JToolBar m_toolbar;
    private String m_selected;
    private final JPanel m_panel;
    private ShapeComponent m_selectedComponent;
    private final Map<String, ShapeInfo> m_shapes = new HashMap<String, ShapeInfo>();
    private final SimpleShape m_defaultShape = new DefaultShape();
    private final ActionListener m_reusableActionListener = new ShapeActionListener();

    /**
     * Default constructor that populates the main window.
    **/
    public DrawingFrame()
    {
        super("Extender-Based Host");

        m_toolbar = new JToolBar("Toolbar");
        m_panel = new JPanel();
        m_panel.setBackground(Color.WHITE);
        m_panel.setLayout(null);
        m_panel.setMinimumSize(new Dimension(400, 400));
        m_panel.addMouseListener(this);
        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(m_toolbar, BorderLayout.NORTH);
        getContentPane().add(m_panel, BorderLayout.CENTER);
        setSize(400, 400);
    }

    /**
     * This method sets the currently selected shape to be used for drawing
     * on the canvas.
     * @param name The name of the shape to use for drawing on the canvas.
    **/
    public void selectShape(String name)
    {
        m_selected = name;
    }

    /**
     * Retrieves the available <tt>SimpleShape</tt> associated with the given name.
     * @param name The name of the <tt>SimpleShape</tt> to retrieve.
     * @return The corresponding <tt>SimpleShape</tt> instance if available or
     *         <tt>null</tt>.
    **/
    public SimpleShape getShape(String name)
    {
        ShapeInfo info = m_shapes.get(name);
        if (info == null)
        {
            return m_defaultShape;
        }
        else
        {
            return info.m_shape;
        }
    }

    /**
     * Injects an available <tt>SimpleShape</tt> into the drawing frame.
     * @param name The name of the injected <tt>SimpleShape</tt>.
     * @param icon The icon associated with the injected <tt>SimpleShape</tt>.
     * @param shape The injected <tt>SimpleShape</tt> instance.
    **/
    public void addShape(String name, Icon icon, SimpleShape shape)
    {
        m_shapes.put(name, new ShapeInfo(name, icon, shape));
        JButton button = new JButton(icon);
        button.setActionCommand(name);
        button.addActionListener(m_reusableActionListener);

        if (m_selected == null)
        {
            button.doClick();
        }

        m_toolbar.add(button);
        m_toolbar.validate();
        repaint();
    }

    /**
     * Removes a no longer available <tt>SimpleShape</tt> from the drawing frame.
     * @param name The name of the <tt>SimpleShape</tt> to remove.
    **/
    public void removeShape(String name)
    {
        m_shapes.remove(name);

        if ((m_selected != null) && m_selected.equals(name))
        {
            m_selected = null;
        }

        for (int i = 0; i < m_toolbar.getComponentCount(); i++)
        {
            JButton sb = (JButton) m_toolbar.getComponent(i);
            if (sb.getActionCommand().equals(name))
            {
                m_toolbar.remove(i);
                m_toolbar.invalidate();
                validate();
                repaint();
                break;
            }
        }

        if ((m_selected == null) && (m_toolbar.getComponentCount() > 0))
        {
            ((JButton) m_toolbar.getComponent(0)).doClick();
        }
    }

    /**
     * Implements method for the <tt>MouseListener</tt> interface to
     * draw the selected shape into the drawing canvas.
     * @param evt The associated mouse event.
    **/
    public void mouseClicked(MouseEvent evt)
    {
        if (m_selected == null)
        {
            return;
        }

        if (m_panel.contains(evt.getX(), evt.getY()))
        {
            ShapeComponent sc = new ShapeComponent(this, m_selected);
            sc.setBounds(evt.getX() - BOX / 2, evt.getY() - BOX / 2, BOX, BOX);
            m_panel.add(sc, 0);
            m_panel.validate();
            m_panel.repaint(sc.getBounds());
        }
    }

    /**
     * Implements an empty method for the <tt>MouseListener</tt> interface.
     * @param evt The associated mouse event.
    **/
    public void mouseEntered(MouseEvent evt)
    {
    }

    /**
     * Implements an empty method for the <tt>MouseListener</tt> interface.
     * @param evt The associated mouse event.
    **/
    public void mouseExited(MouseEvent evt)
    {
    }

    /**
     * Implements method for the <tt>MouseListener</tt> interface to initiate
     * shape dragging.
     * @param evt The associated mouse event.
    **/
    public void mousePressed(MouseEvent evt)
    {
        Component c = m_panel.getComponentAt(evt.getPoint());
        if (c instanceof ShapeComponent)
        {
            m_selectedComponent = (ShapeComponent) c;
            m_panel.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
            m_panel.addMouseMotionListener(this);
            m_selectedComponent.repaint();
        }
    }

    /**
     * Implements method for the <tt>MouseListener</tt> interface to complete
     * shape dragging.
     * @param evt The associated mouse event.
    **/
    public void mouseReleased(MouseEvent evt)
    {
        if (m_selectedComponent != null)
        {
            m_panel.removeMouseMotionListener(this);
            m_panel.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
            m_selectedComponent.setBounds(
                evt.getX() - BOX / 2, evt.getY() - BOX / 2, BOX, BOX);
            m_selectedComponent.repaint();
            m_selectedComponent = null;
        }
    }

    /**
     * Implements method for the <tt>MouseMotionListener</tt> interface to
     * move a dragged shape.
     * @param evt The associated mouse event.
    **/
    public void mouseDragged(MouseEvent evt)
    {
        m_selectedComponent.setBounds(
            evt.getX() - BOX / 2, evt.getY() - BOX / 2, BOX, BOX);
    }

    /**
     * Implements an empty method for the <tt>MouseMotionListener</tt>
     * interface.
     * @param evt The associated mouse event.
    **/
    public void mouseMoved(MouseEvent evt)
    {
    }

    /**
     * Simple action listener for shape tool bar buttons that sets
     * the drawing frame's currently selected shape when receiving
     * an action event.
    **/
    private class ShapeActionListener implements ActionListener
    {
        public void actionPerformed(ActionEvent evt)
        {
            selectShape(evt.getActionCommand());
        }
    }

    /**
     * This class is used to record the various information pertaining to
     * an available shape.
    **/
    private static class ShapeInfo
    {
        public String m_name;
        public Icon m_icon;
        public SimpleShape m_shape;
        public ShapeInfo(String name, Icon icon, SimpleShape shape)
        {
            m_name = name;
            m_icon = icon;
            m_shape = shape;
        }
    }
}