uni

Triangle.java (3856B)

---

 import java.awt.*;
 
 /**
  * A triangle that can be manipulated and that draws itself on a canvas.
  * 
  * @author	Michael Kolling and David J. Barnes
  * @version 1.0  (15 July 2000)
  */
 
 public class Triangle
 {
     private int height;
     private int width;
 	private int xPosition;
 	private int yPosition;
 	private String color;
 	private boolean isVisible;
 	
 	@Override
 	public String toString(){
 	   return "height: " + height + 
 	          ", width: " + width + 
 	          ", xPosition: " + xPosition + 
 	          ", yPosition: " + yPosition + 
 	          ", color: " + color + 
 	          ", isVisible: " + isVisible;
 	}
 
     /**
      * Create a new triangle at default position with default color.
      */
     public Triangle()
     {
 		height = 30;
 		width = 40;
 		xPosition = 50;
 		yPosition = 15;
 		color = "green";
 		isVisible = false;
     }
 
 	/**
 	 * Make this triangle visible. If it was already visible, do nothing.
 	 */
 	public void makeVisible()
 	{
 		isVisible = true;
 		draw();
 	}
 	
 	/**
 	 * Make this triangle invisible. If it was already invisible, do nothing.
 	 */
 	public void makeInvisible()
 	{
 		erase();
 		isVisible = false;
 	}
 	
     /**
      * Move the triangle a few pixels to the right.
      */
     public void moveRight()
     {
 		moveHorizontal(20);
     }
 
     /**
      * Move the triangle a few pixels to the left.
      */
     public void moveLeft()
     {
 		moveHorizontal(-20);
     }
 
     /**
      * Move the triangle a few pixels up.
      */
     public void moveUp()
     {
 		moveVertical(-20);
     }
 
     /**
      * Move the triangle a few pixels down.
      */
     public void moveDown()
     {
 		moveVertical(20);
     }
 
     /**
      * Move the triangle horizontally by 'distance' pixels.
      */
     public void moveHorizontal(int distance)
     {
 		erase();
 		xPosition += distance;
 		draw();
     }
 
     /**
      * Move the triangle vertically by 'distance' pixels.
      */
     public void moveVertical(int distance)
     {
 		erase();
 		yPosition += distance;
 		draw();
     }
 
     /**
      * Slowly move the triangle horizontally by 'distance' pixels.
      */
     public void slowMoveHorizontal(int distance)
     {
 		int delta;
 
 		if(distance < 0) 
 		{
 			delta = -1;
 			distance = -distance;
 		}
 		else 
 		{
 			delta = 1;
 		}
 
 		for(int i = 0; i < distance; i++)
 		{
 			xPosition += delta;
 			draw();
 		}
     }
 
     /**
      * Slowly move the triangle vertically by 'distance' pixels.
      */
     public void slowMoveVertical(int distance)
     {
 		int delta;
 
 		if(distance < 0) 
 		{
 			delta = -1;
 			distance = -distance;
 		}
 		else 
 		{
 			delta = 1;
 		}
 
 		for(int i = 0; i < distance; i++)
 		{
 			yPosition += delta;
 			draw();
 		}
     }
 
     /**
      * Change the size to the new size (in pixels). Size must be >= 0.
      */
     public void changeSize(int newHeight, int newWidth)
     {
 		erase();
 		height = newHeight;
 		width = newWidth;
 		draw();
     }
 
     /**
      * Change the color. Valid colors are "red", "yellow", "blue", "green",
 	 * "magenta" and "black".
      */
     public void changeColor(String newColor)
     {
 		color = newColor;
 		draw();
     }
 
 	/*
 	 * Draw the triangle with current specifications on screen.
 	 */
 	private void draw()
 	{
 		if(isVisible) {
 			Canvas canvas = Canvas.getCanvas();
 			int[] xpoints = { xPosition, xPosition + (width/2), xPosition - (width/2) };
 			int[] ypoints = { yPosition, yPosition + height, yPosition + height };
 			canvas.draw(this, color, new Polygon(xpoints, ypoints, 3));
 			canvas.wait(10);
 		}
 	}
 
 	/*
 	 * Erase the triangle on screen.
 	 */
 	private void erase()
 	{
 		if(isVisible) {
 			Canvas canvas = Canvas.getCanvas();
 			canvas.erase(this);
 		}
 	}
 }