FreeFormEdit.java

package macrolanguage;
import java.awt.*;
import java.awt.event.*;
import macrolanguage.EditToolbar;
import macrolanguage.NotAContainerException;

public class FreeFormEdit extends Frame
      implements  KeyListener, WindowListener
{
  /**
   * The constructor creates the listeners with the correct layout
   * for the free form design.
  **/
  public FreeFormEdit()
  {
    super();

    addWindowListener(this);
    addKeyListener(this);
    addMouseListener(mouseManager);

    setLayout(new FlowLayout());

    // default size.
    setSize(100,100);

    show();
  }

  /**
   * Add a component to an x and y location.
   * This method will be called by the user putting a component on
   * the form or an embedded container. This method throws a
   * NotAContainerException when the x and y location points at a
   * component, since components cannot be placed on other components
   * in Java (this is untrue with regarding lightweight components).
  **/
  public void add(Component c, int x, int y) throws NotAContainerException
  {
    // Check whether there is a component at the x and y location
    // and if so throw NotAContainerException.
    Component temp = getComponentAt(x,y);
    if(!(temp instanceof Container))
      throw (new NotAContainerException("Tried to add a component to something other than a container."));

    // Add listeners to events regarding these componenets.
    // The listening is performed in the MouseManager class to avoid
    // bloating this class.
    c.addMouseMotionListener(mouseManager);
    c.addMouseListener(mouseManager);

    // Add the component to the container.
    ((Container)temp).add(c);

    // Set the relative x and y location.
    c.setLocation(x, y);
  }

  /**
   * Set the selection Component to be the selected Component.
  **/
  public void setSelection(Component selection)
  {
    if (this.selection != selection)
    {
      this.selection = selection;
      repaint();
    }
  }

  /**
   * Places the component comp on the next click on the free form
   * edit surface.
  **/
  public void placeComponentOnNextClick(Component comp)
  {
    // Change the cursor so it will be evident we are in the middle
    // of a drop operation.
    setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
    mouseManager.placeComponentOnNextClick(comp);
  }

  /**
   *
  **/
  public void removeSelection()
  {
    if(selection != this)
    {
      remove(selection);
      selection = this;
      repaint();
    }
  }

  /**
   * This method is a part of the keylistener interface used
   * to listen to keyboard events.
  **/
  public void keyTyped(java.awt.event.KeyEvent ev)
  {
  }

  /**
   * This method is a part of the keylistener interface used
   * to listen to keyboard events.
  **/
  public void keyPressed(java.awt.event.KeyEvent ev)
  {
  }

  /**
   * This method is a part of the keylistener interface used
   * to listen to keyboard events.
  **/
  public void keyReleased(java.awt.event.KeyEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowOpened(java.awt.event.WindowEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowClosing(java.awt.event.WindowEvent ev)
  {
    System.exit(0);
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowClosed(java.awt.event.WindowEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowIconified(java.awt.event.WindowEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowDeiconified(java.awt.event.WindowEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowActivated(java.awt.event.WindowEvent ev)
  {
  }

  /**
   * This method is a part of the Windowlistener interface used
   * to listen to window events.
  **/
  public void windowDeactivated(java.awt.event.WindowEvent ev)
  {
  }


  /**
   * The paint method draws the marking around the selection.
  **/
  public void paint(Graphics g)
  {
    super.paint(g);

    // If the frame is selected do nothing.
    if(selection != this)
    {
      // If the selection is not in this container.
      if(selection.getParent() != this)
        // Draw little squares around the four corners of the selected component.
        drawSelection(selection,
                      selection.getParent().getGraphics());
      else
        // Draw little squares around the four corners of the selected component.
        drawSelection(selection, g);
    }
  }

  /**
   * Draw a thin line around the selected component.
   **/
  private void drawSelection(Component select, Graphics g)
  {
    g.setColor(Color.black);

    g.fillRect(select.getLocation().x - SQUARE_SIZE,
               select.getLocation().y - SQUARE_SIZE,
               select.getSize().width + SQUARE_SIZE,
               select.getSize().height + SQUARE_SIZE);
  }

  // The currently selected component. By default this frame.
  private Component selection = this;

  // The MouseManager takes over the full responsibility of manageing the
  // mouse events for the form designing.
  private MouseManager mouseManager = new MouseManager(this);

  // The default width of the line surrounding selected components.
  private static final int SQUARE_SIZE = 2;
}