Draw a rectangle when you press a button?

[Xyexs]

I stole this topic, original is found at bottom of post
Hi!
In order to learn i wrote this.

package xyexs.name.src;




import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JPanel;




public class Panel extends JPanel {




	public int x = 0;
	public int y = 0;




	public void paintComponent(Graphics g) {
		super.paintComponents(g);
		g.setColor(Reference.BACKGROUND_COLOR);
		g.fillRect(0, 0, Reference.WINDOW_X, Reference.WINDOW_Y);
		g.setColor(Reference.SNAKE_COLOR);
		g.fillRect(y, x, Reference.PIXEL_SIZE, Reference.PIXEL_SIZE);
	}




	public Panel() {
		keyHandler handlerObject = new keyHandler();
		setFocusable(true);
		addKeyListener(handlerObject);
	}




	public Dimension getPreferredSize() {
		return new Dimension(Reference.WINDOW_X, Reference.WINDOW_Y);
	}




	private class keyHandler extends KeyAdapter {
		@Override
		public void keyPressed(KeyEvent key) {
			if (key.getKeyCode() >= 37 && key.getKeyCode() <= 40) {




				switch (key.getKeyCode()) {




					case KeyEvent.VK_LEFT: {
						// left
						x = x - 1;
					}
					case KeyEvent.VK_UP: {
						// up
						x = x + 1;
					}
					case KeyEvent.VK_RIGHT: {
						// right
						x = x + 1;
					}
					case KeyEvent.VK_DOWN: {
						// down
						y = y + 1;
					}
				}
				repaint();
			}
		}
	}
}

It's supposed to move the box in the direction of the arrow you press.




The weird thing is that if i press up it ... see below...

If i press...	It moves...
Up	Down
Right	Right/down
Down	Right
Left	Nowhere

---

Original post

package xyexs.name.src;

import java.awt.Graphics;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JPanel;

public class Panel extends JPanel {
	public void paintPixel(int pixelX, int pixelY) {
		Graphics g = getGraphics();
		super.paintComponents(g);
		g.setColor(Reference.SNAKE_COLOR);
		g.fillRect(pixelX * Reference.PIXEL_SIZE,
				pixelY * Reference.PIXEL_SIZE, pixelX * Reference.PIXEL_SIZE
						+ Reference.PIXEL_SIZE, pixelY * Reference.PIXEL_SIZE
						+ Reference.PIXEL_SIZE);
	}

	public Panel() {
		keyHandler handlerObject = new keyHandler();
		setFocusable(true);
		setBackground(Reference.BACKGROUND_COLOR);
		addKeyListener(handlerObject);
	}

	private class keyHandler extends KeyAdapter {
		@Override
		public void keyReleased(KeyEvent key) {
			if (key.getKeyCode() >= 37 && key.getKeyCode() <= 40) {
				paintPixel()
			}
		}
	}
}

^ the above code (as i expected) won't work, i want it to draw a "pixel" (which is a 50 X 50 rectangle), it just does NOTHING... help?

EDIT: does in fact work! Just not wen called from main using objectname.paintPixel(2,2)

[KevinWorkman]

That is not how you do custom painting. Read this instead: Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

[Xyexs]

Okay, thanks :D

[DarrylBurke]

And in general: never use getGraphics() of a Component. At least, not unless you have a very thorough understanding of the painting mechanism.

db

[Xyexs]

After reading for a while... doesn't that run automatically?(the paintComponent method)
That is why i did this.. which failed totally

[DarrylBurke]

Wow, you went through the custom painting tutorial in 18 minutes? The first time I read through it, it took me almost two hours!

db

[KevinWorkman]

After reading for a while... doesn't that run automatically?(the paintComponent method)
That is why i did this.. which failed totally

You either read very fast, or didn't try any of the examples, which should explain anything you're confused about.

The paintComponent() method is called when the component needs to be painted, which can either be triggered by the OS or by the programmer by calling repaint().

[jim829]

Wow, you went through the custom painting tutorial in 18 minutes? The first time I read through it, it took me almost two hours!

db

Nor did I miss the "first time" reference. I have lost track of how many times I have read and re-read articles or white papers (and then read them again).

Regards,
Jim

[JosAH]

Wow, you went through the custom painting tutorial in 18 minutes?

16 minutes according to my data.

kind regards,

Jos

[Xyexs]

Stole the topic- se OP

Edit: thats a bad idea, making a new topic

[DarrylBurke]

16 minutes according to my data.

kind regards,

Jos

#2 at 10:34
#5 at 10:52

db

[JosAH]

#2 at 10:34
#5 at 10:52

#2 is Kevin; #3 should be 10.36 your time, so it's 16 minutes ;-)

kind regards,

Jos

[DarrylBurke]

I computed it from the time the link was supplied.

Your approach is more correct.

db <- maths impaired

[KevinWorkman]

OP: your current problem is caused by your case statements falling through. Recommended reading: The switch Statement (The Java™ Tutorials > Learning the Java Language > Language Basics)

[gimbal2]

OP: your current problem is caused by your case statements falling through. Recommended reading: The switch Statement (The Java™ Tutorials > Learning the Java Language > Language Basics)

Deja Vu. I see DB's dupe detector needs new batteries.

http://www.java-forums.org/new-java/...g-weirdly.html