Re: How to continue program operation while animation loop is running

ebot9000 · #11 26-Sep-2009, 11:30

Here's specifically what you need to import in the RefreshGraphic class to get it to work

JAVA Code:

import java.awt.Color;
import acm.graphics.GCompound;
import acm.graphics.GLine;
import acm.program.GraphicsProgram;

TurboPT · #12 26-Sep-2009, 11:40

Ok, I'll give a shot again (won't be at this very minute, though) and see how it goes.

ebot9000 · #13 26-Sep-2009, 11:44

Yes, please take your time. Far from critical!

Thanks so much,
Ethan

ebot9000 · #14 26-Sep-2009, 13:44

I rewrote the TestRefreshGraphic code so that it requires some threading in order to operate. Basically, if you can show me how to rewrite this and/or the RefreshGraphic class, I think I'll understand how to implement threading.

JAVA Code:

/* Simple program that requires threading to function
 */

import acm.graphics.GCompound;
import acm.graphics.GLabel;
import acm.program.GraphicsProgram;

public class TestRefreshGraphic extends GraphicsProgram {
	
	public void run() {
		GLabel hello = new GLabel("Hello, world of threading!");
		add(hello, (getWidth() - hello.getWidth()) / 2, (getHeight() - hello.getHeight()) / 2);
		
		GCompound gc = refresh.addTo(20, 20);
		add(gc, getWidth() / 2, (getHeight() + gc.getHeight()) / 2);
		refresh.animate(); // while(true) loop that needs to be interrupted after pause
		
		pause(10000); // We never get here
		
		removeAll();
		GLabel fun = new GLabel("Now, wasn't that fun?");
		add(fun, (getWidth() - fun.getWidth()) / 2, (getHeight() - fun.getHeight()) / 2);
	}
	
	private RefreshGraphic refresh = new RefreshGraphic();
}

Your tips are very much appreciated!
-Ethan

TurboPT · #15 29-Sep-2009, 08:20

Ok, after getting by an ISP issue, and working with another PC (the other I tried to use initially only has gcj, and it might not have everything necessary), but I was able to get your classes to compile (finally) and I saw the counter-clockwise 'spinner', so at least this is a step forward!

So, I can tinker with this more now, and I've also come to the realization that it's been about 5, if not 6, years since I've tinkered with Java threads, so I might be back to a small learning curve myself

. Some threading things I do recall have been deprecated, so I'll have some relearning to do as well. (which is not a problem, a refresher is not a bad idea at this point)

ebot9000 · #16 29-Sep-2009, 11:37

To my surprise (they were supposed to cover the "Main" method) the professor covered threading in the class I just watched. I was able to rewrite the RefreshGraphic class and the TestRefreshGraphic class so that it worked just fine.

I'll post in a few moments when I get in.

Sone methods are deprecated from what I could see in the javadocs. I believe start() & interrupt() are what are used to begin & end a thread, but I'd be the wrong guy to confirm this

ebot9000 · #17 29-Sep-2009, 12:01

So in the interest of closure, I'll post the code that implements threading and appears to function properly.

First off, I went into the RefreshGraphic class as posted on page 1 of this topic, and changed the "public void animate()" method to "public void run()" Otherwise that code stayed the same and it still implements Runnable.

Then I re-wrote the TestRefreshGraphic class:

JAVA Code:

/* Simple program that requires threading to function
 */

import acm.graphics.GCompound;
import acm.graphics.GLabel;
import acm.program.GraphicsProgram;

public class TestRefreshGraphic extends GraphicsProgram {
	
	public void init() {
		GLabel hello = new GLabel("Hello, world of threading!");
		add(hello, (getWidth() - hello.getWidth()) / 2, (getHeight() - hello.getHeight()) / 2);
		
		GCompound gc = refresh.addTo(20, 20);
		add(gc, getWidth() / 2, (getHeight() + gc.getHeight()) / 2);
		Thread t = new Thread(refresh);
		t.start();
		
		pause(10000);
		t.interrupt();
		
		removeAll();
		GLabel fun = new GLabel("Now, wasn't that fun?");
		add(fun, (getWidth() - fun.getWidth()) / 2, (getHeight() - fun.getHeight()) / 2);
	}
	
	private RefreshGraphic refresh = new RefreshGraphic();
}

TurboPT, I know you jumped through some hoops to help me out. Thanks so much for taking the time out and pointing me in the right direction!

Of course, if you see any improvements to the code, I'd welcome them in the interest of edumacatin myself.

Cheers!
-Ethan

TurboPT · #18 29-Sep-2009, 12:06

I got something working too, and here's what I came up with:
RefreshGraphic class:
[I reworked parts of addTo(), added two functions, renamed animate() to run()]

JAVA Code:

import java.awt.Color;
import acm.graphics.*;
import acm.program.*;


public class RefreshGraphic extends GraphicsProgram implements Runnable{
	GCompound gc = new GCompound();
	GLine[] lines;
    boolean go = false;
    Thread T;
	
	// constructor
	public RefreshGraphic() 
    {         
        T = new Thread(this);
    }
	
	/** adds the refresh compound to the canvas
	 * @param size radius of the graphic
	 * @param sides number of lines in the graphic
	 */
	public GCompound addTo(double size, int sides) {
		double degrees = 360.0 / sides;
        double radians = 0.0;
		double angle = 0.0;
		double angleForComputation = 0.0;
		lines = new GLine[sides];
		
		for (int i = 0; i < sides; i++) {
			if (angle <= 90) angleForComputation = angle;
			else if (angle <= 180) angleForComputation = angle - 90;
			else if (angle <= 270) angleForComputation = angle - 180;
			else  angleForComputation = angle - 270;
			
            radians = Math.toRadians(angleForComputation);
			
            double firstX = ((Math.cos(radians)) * size) / 2;
			double firstY = ((Math.sin(radians)) * size) / 2; 
			double secondX = firstX * 2;
			double secondY = firstY * 2;
			
			if (angle <= 90) {
				lines[i] = new GLine(firstX, -firstY, secondX, -secondY);
			} else if (angle <= 180) {
				lines[i] = new GLine(-firstY, -firstX, -secondY, -secondX);
			} else if (angle <= 270) {
				lines[i] = new GLine(-firstX, firstY, -secondX, secondY);
			} else {
				lines[i] = new GLine(firstY, firstX, secondY, secondX);
			}
			
            lines[i].setColor(Color.BLUE);
			angle += degrees;
			gc.add(lines[i]);
        }
		
		return gc;
	}
	
    public void killAnimation()
    {
        go = false;
    }
    
    public void startAnimation()
    {
        go = true;
        T.start();
    }
    
	/** Animates the RefreshGraphic
	 */
	public void run() {
		System.out.println("animate() entered!");
        int i = 0;
		while(go) {
			lines[i].setColor(Color.RED);
			if (i == 0) {
				lines[lines.length - 1].setColor(Color.WHITE);
				lines[lines.length - 2].setColor(Color.BLUE);
			} else if (i == 1) {
				lines[0].setColor(Color.WHITE);
				lines[lines.length - 1].setColor(Color.BLUE);
			} else {
				lines[i - 1].setColor(Color.WHITE);
				lines[i - 2].setColor(Color.BLUE);
			}
			pause(40);
			if (i < lines.length - 1) {
				i++;
			} else {
				i = 0;
			}
		}
		System.out.println("animate() exited!");
	}
}

...and the TestRefreshGraphic class:
[I added extra labels and pause()'s for brief viewing in the GUI output]

JAVA Code:

import acm.graphics.GCompound;
import acm.graphics.GLabel;
import acm.program.GraphicsProgram;

public class TestRefreshGraphic extends GraphicsProgram {
    private RefreshGraphic refresh = new RefreshGraphic();

	public void run()
    {
        GLabel hello = new GLabel("Hello, world of threading!");
		add(hello, (getWidth() - hello.getWidth()) / 2, (getHeight() - hello.getHeight()) / 2);
		
        GCompound gc = refresh.addTo(20, 20);
		add(gc, getWidth() / 2, (getHeight() + gc.getHeight()) / 2);
    
        refresh.startAnimation(); // while(go) loop that needs to be interrupted after pause [it will!]
        pause(1000);
        
		GLabel hello2 = new GLabel("Animation already Running!");
		add(hello2, (getWidth() - hello2.getWidth()) / 2, (getHeight() + gc.getHeight() + hello.getHeight() * 4) / 2);
        System.out.println("Surpassed Start!");

		pause(10000); // We do get past this point now.
        
        hello2.setLabel("Passed the 10-sec. pause");
		System.out.println("Surpassed Pause!");
		pause(2000);
        
        hello2.setLabel("Stopping Animation");
        refresh.killAnimation();
		pause(2000);

        removeAll();
		GLabel fun = new GLabel("Now, wasn't THAT fun?");
		add(fun, (getWidth() - fun.getWidth()) / 2, (getHeight() - fun.getHeight()) / 2);
    }
}

The deprecated functions I know are: stop(), suspend(), resume(), and destroy() -- all Thread class functions.

EDIT:
So, somewhere between startAnimation() and killAnimation() is where the youtube retrieval stuff would go.

ebot9000 · #19 29-Sep-2009, 12:17

Oh, that's interesting. You put the threading into the RefreshGraphic class itself. Is that better style than putting it into the class that calls it?

In a more complicated program is it better to have classes manage their own threads like that, or is it better to have them all in the main class?

Thanks again,
Ethan

ebot9000 · #20 29-Sep-2009, 12:18

Quote:

EDIT:
So, somewhere between startAnimation() and killAnimation() is where the youtube retrieval stuff would go.

Yup, I've already extrapolated to my other program! It works!

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