/**

@author John M (http://sourceforge.net/users/nextdesign)

<b>Changelog:</b>
<ul>
	<li>2010/01/16 by Nicolás Carranza: - changed to make it work with the mouse too - draw always when pressure &gt; 0</li>
	<li>2011/06/23 by Nicolás Carranza: - changed to use the AwtPenToolkit - added note about technique to get better performance</li>
</ul>
*/

import java.awt.*;
import jpen.event.*;
import jpen.*;
import jpen.owner.multiAwt.AwtPenToolkit;
import java.awt.geom.*;
import javax.swing.*;

public class DrawingSurface extends PenAdapter
{
	private static final long serialVersionUID = 1L;

	public static void main(String... args) throws Throwable{
		new DrawingSurface();
	}

	JFrame frame=new JFrame("Drawing Surface");;
	JPanel panel=new JPanel();
	Graphics2D g2d;

	Point2D.Float prevLoc=new Point2D.Float();// previous location of cursor
	Point2D.Float loc=new Point2D.Float();// current location of cursor

	/* brush dynamics */
	float       brushSize;
	float       opacity;
	BasicStroke stroke;

	{
		// setup the window and the panel
		panel.setBackground(Color.white);
		/* set the cursor to the crosshair so we can see
		 what we're drawing 
		 underneath */
		panel.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
		frame.setContentPane(panel);
		frame.setSize(new Dimension(800, 600));
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		// Use the AwtPenToolkit to register a PenListener on the panel:
		AwtPenToolkit.addPenListener(panel, this);
		// setup the mouse to cause a pressure level event when the left button is pressed:
		PenManager pm=AwtPenToolkit.getPenManager();
		pm.pen.levelEmulator.setPressureTriggerForLeftCursorButton(0.5f);

		// show the window and setup the g2d
		frame.setVisible(true);
		g2d = (Graphics2D)panel.getGraphics();
		// make the lines smooth
		g2d.setRenderingHint(RenderingHints.KEY_RENDERING,
				RenderingHints.VALUE_RENDER_QUALITY);
		g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,
				RenderingHints.VALUE_STROKE_PURE);
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
				RenderingHints.VALUE_ANTIALIAS_ON);
	}

	@Override
	public void penLevelEvent(PLevelEvent ev)
	{
		// if this event was not a movement, do nothing
		if(!ev.isMovement())
			return;

		// set the brush's size, and opacity relative to the pressure
		float pressure=ev.pen.getLevelValue(PLevel.Type.PRESSURE);
		brushSize = pressure * 10;
		opacity = pressure * 255;
		/* since getLevelValue(PLevel.Type.PRESSURE) returns 0 -> 1,
		 we need to multiply that by 255 to
		 get the correct amount of color
		 (0 -> 255). When then subtract it
		 from 255 so we start with a black line
		 with full pressure */

		// get the current cursor location
		loc.x = ev.pen.getLevelValue(PLevel.Type.X);
		loc.y = ev.pen.getLevelValue(PLevel.Type.Y);

		if (brushSize>0)
		{
			if (ev.pen.getKind() == PKind.valueOf(PKind.Type.ERASER))	// using the eraser, create a white line, effectively "erasing" the black line
			{
				// set the color to white, and create the stroke
				g2d.setColor(Color.white);
				stroke = new BasicStroke(brushSize * 2); // make it a bit more sensitive
			}else// default, we want to draw a black line onto the screen.
			{
				// set the opacity, and create the stroke
				g2d.setColor(new Color((int)opacity, (int)opacity, 255, 255));
				stroke=new BasicStroke(brushSize,
							 BasicStroke.CAP_ROUND, // round line endings
							 BasicStroke.JOIN_MITER
															);
			}

			// draw a line between the current and previous locations
			g2d.setStroke(stroke);
			g2d.draw(new Line2D.Float(prevLoc, loc));
		}

		// set the current position to the previous position
		prevLoc.setLocation(loc);

		// paint pane to draw brush info on
		g2d.setColor(Color.white);
		g2d.fillRect(0, 5, 155, 35);

		// draw the brush info in the top-left corner
		g2d.setColor(Color.black);
		g2d.drawString(("Brush size: " + brushSize), 5, 20);
		g2d.drawString(("Opacity: " + opacity), 5, 35);
		
		//NOTE: if performance is an issue, you can get better performance by painting on an off-screen image and requesting a paint of the dirty region when penTock() is called, check the jpen.demo.PenCanvas source code for an example of this technique.
	}
}