LinePrinter.java

package org.reprap.devices.pseudo;

import java.io.IOException;

import org.reprap.Extruder;
import org.reprap.devices.GenericStepperMotor;

/**
 * This is a pseudo device that provides an apparent single device
 * for plotting lines.
 */
public class LinePrinter {

	
	/**
	 * Stepper motors
	 */
	private GenericStepperMotor motorX;
	private GenericStepperMotor motorY;
	private Extruder extruder;

	/**
	 * 
	 */
	private boolean initialisedXY = false;
	
	/**
	 * 
	 */
	private int currentX, currentY;
	
	/**
	 * @param motorX
	 * @param motorY
	 * @param extruder
	 */
	public LinePrinter(GenericStepperMotor motorX, GenericStepperMotor motorY, Extruder extruder) {
		this.motorX = motorX;
		this.motorY = motorY;
		this.extruder = extruder;
	}
	
	public void changeExtruder(Extruder e)
	{
		extruder = e;
	}
	
	/**
	 * @throws IOException
	 */
	public void initialiseXY() throws IOException {
		if (!initialisedXY) {
			currentX = motorX.getPosition();
			currentY = motorY.getPosition();
			initialisedXY = true;
		}
	}
	
	/**
	 * Only call these when you know what you're doing...
	 */
	public void zeroX()
	{
		currentX = 0;
	}
	public void zeroY()
	{
		currentY = 0;
	}

	/**
	 * Move to a 2-space point in a direct line.  At the moment this is just the pure 2D Bresenham algorithm.
	 * It would be good to generalise this to a 3D DDA.
	 * @param endX
	 * @param endY
	 * @param movementSpeed
	 * @throws IOException
	 */
	public void moveTo(int endX, int endY, int movementSpeed) throws IOException {
		initialiseXY();

		if (currentX == endX && currentY == endY)
			return;
		
		GenericStepperMotor master, slave;

		int x0, x1, y0, y1;
		
		// Whichever is the greater distance will be the master
		// From an algorithmic point of view, we'll just consider
		// the master to be X and the slave to be Y, which eliminates
		// the need for mapping quadrants.
		if (Math.abs(endX - currentX) > Math.abs(endY - currentY)) {
			master = motorX;
			slave = motorY;
			x0 = currentX;
			x1 = endX;
			y0 = currentY;
			y1 = endY;
		} else {
			master = motorY;
			slave = motorX;
			x0 = currentY;
			x1 = endY;
			y0 = currentX;
			y1 = endX;
		}
				
		master.setSync(GenericStepperMotor.SYNC_NONE);
		if (y0 < y1)
			slave.setSync(GenericStepperMotor.SYNC_INC);
		else
			slave.setSync(GenericStepperMotor.SYNC_DEC);

		int deltaY = Math.abs(y1 - y0); 
		//int deltaX = Math.abs(x1 - x0); 
				
		master.dda(movementSpeed, x1, deltaY);
		
		slave.setSync(GenericStepperMotor.SYNC_NONE);

		currentX = endX;
		currentY = endY;
	}
	
	/**
	 * Correct a speed change (in (0, 1]) for the fact that it's click times that get
	 * send to the controller.
	 * @param oldSpeed
	 * @param factor
	 * @return
	 */
	
	public static int speedFix(int oldSpeed, double factor)
	{
		if(factor <= 0 || factor > 1)
			return oldSpeed;
		
		double x = 256 + (oldSpeed - 256)/factor;
		int speed = (int)Math.round(x);
		if(speed < 1)
			speed = 1;
		if(speed > 255)
			speed = 255;
		return speed;		
	}
	

	/**
	 * Correct the speed for the angle of the line to the axes
	 * @param movementSpeed
	 * @param dx
	 * @param dy
	 * @return
	 */
	private int angleSpeed(int movementSpeed, double dx, double dy)	{
		double length = Math.sqrt(dx*dx + dy*dy);
		if(length == 0)
			return movementSpeed;
		double longSide = Math.max(Math.abs(dx), Math.abs(dy));
		return speedFix(movementSpeed, longSide/length);
	}

	/**
	 * @param endX
	 * @param endY
	 * @param movementSpeed
	 * @param extruderSpeed
	 * @param turnOff True if extruder should be turned off after this segment is printed.
	 * @throws IOException
	 */
	public void printTo(int endX, int endY, int movementSpeed, 
			int extruderSpeed, boolean turnOff) throws IOException {
		// Determine the extruder speed, based on the geometry of the line
		// to be printed
		double dx = endX - currentX;
		double dy = endY - currentY;
		extruder.setExtrusion(extruderSpeed);
		moveTo(endX, endY, angleSpeed(movementSpeed, dx, dy));
		if(turnOff)
			extruder.setExtrusion(0);
	}
	
	public void stopExtruding() throws IOException
	{
		extruder.setExtrusion(0);
	}
	
	public void stopValve() throws IOException
	{
		extruder.setValve(false);
	}
	
	/**
	 * @param startX
	 * @param startY
	 * @param endX
	 * @param endY
	 * @param movementSpeed
	 * @param extruderSpeed
	 * @param turnOff True if the extruder should be turned off at the end of this segment.
	 * @throws IOException
	 */
	public void printLine(int startX, int startY, int endX, int endY, 
			int movementSpeed, int extruderSpeed, boolean turnOff) throws IOException {
		moveTo(startX, startY, movementSpeed);
		printTo(endX, endY, movementSpeed, extruderSpeed, turnOff);
	}

	/**
	 * @return Returns the currentX.
	 */
	public int getCurrentX() {
		return currentX;
	}
	/**
	 * @return Returns the currentY.
	 */
	public int getCurrentY() {
		return currentY;
	}
}