/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */
package je3.gui;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.List;  // Disambiguate from java.awt.List
import java.util.ArrayList;
import je3.graphics.PolyLine;

/**
 * This custom component allows the user to scribble, and retains the scribbles
 * so that they can be redrawn when needed.  It uses the PolyLine custom Shape
 * implementation defined elsewhere in this book, and demonstrates event
 * handling with low-level event processing methods.
 */
public class ScribblePane extends JComponent {
    List lines;             // The PolyLines that comprise this scribble
    PolyLine currentLine;   // The PolyLine currently being drawn
    Stroke stroke;          // How to draw the lines

    public ScribblePane() {
	setPreferredSize(new Dimension(450,200)); // We need a default size
	lines = new ArrayList();                  // Initialize a list of lines
	stroke = new BasicStroke(3.0f);           // Lines are 3 pixels wide

	// Register interest in mouse button and mouse motion events, so
	// that processMouseEvent() and processMouseMotionEvent() will be 
	// invoked, even if no event listeners are registered.
	enableEvents(AWTEvent.MOUSE_EVENT_MASK |
		     AWTEvent.MOUSE_MOTION_EVENT_MASK);
    }

    /** We override this method to draw ourselves. */
    public void paintComponent(Graphics g) {
	// Let the superclass do its painting first
	super.paintComponent(g);

	// Make a copy of the Graphics context so we can modify it
	// We cast it at the same time so we can use Java2D graphics
	Graphics2D g2 = (Graphics2D) (g.create()); 

	// Our superclass doesn't paint the background, so do this ourselves.
	g2.setColor(getBackground());
	g2.fillRect(0, 0, getWidth(), getHeight());

	// Set the line width and color to use for the foreground
	g2.setStroke(stroke);
	g2.setColor(this.getForeground());

	// Now loop through the PolyLine shapes and draw them all
	int numlines = lines.size();
	for(int i = 0; i < numlines; i++)
	    g2.draw((PolyLine)lines.get(i));
    }

    /**
     * Erase all lines and repaint.  This method is for the convenience of
     * programs that use this component.
     */
    public void clear() {
	lines.clear();
	repaint();
    }

    /**
     * We override this method to receive notification of mouse button events.
     * See also the enableEvents() call in the constructor method.
     */
    public void processMouseEvent(MouseEvent e) {
	// If the type and button are correct, then process it.
	if (e.getButton() == MouseEvent.BUTTON1) {
	    if (e.getID() == MouseEvent.MOUSE_PRESSED) {
		// Start a new line on mouse down
		currentLine = new PolyLine(e.getX(), e.getY());
		lines.add(currentLine);
		e.consume();
	    }
	    else if (e.getID() == MouseEvent.MOUSE_RELEASED) {
		// End the line on mouse up
		currentLine = null;
		e.consume();
	    }
	}

	// The superclass method dispatches to registered event listeners
	super.processMouseEvent(e);
    }

    /**
     * We override this method to receive notification of mouse motion events.
     */
    public void processMouseMotionEvent(MouseEvent e) {
	if (e.getID() == MouseEvent.MOUSE_DRAGGED && // If we're dragging
	    currentLine != null) {                   // and a line exists
	    currentLine.addSegment(e.getX(), e.getY());  // Add a line segment
	    e.consume();

	    // Redraw the whole component.
	    // Exercise: optimize this by passing the bounding box
	    // of the region that needs redrawing to the repaint() method.
	    // Don't forget to take line width into account, however.
	    repaint();
	}

	super.processMouseMotionEvent(e);
    }
}