package question1;
import java.awt.*;
import java.awt.geom.*;

/**
* A circle 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 Circle
{
   
/** Diamètre. */
   
private int diameter;
   
/** Position horizontale. */
   
private int xPosition;
   
/** Position verticale. */
   
private int yPosition;
   
/** Couleur. */
   
private String color;
   
/** Booléen de visibilité. */
   
private boolean isVisible;
   
   
/**
     * Create a new circle at default position with default color.
     */
   
public Circle()
    {
       
diameter = 30;
        xPosition =
20;
        yPosition =
60;
        color =
"blue";
        isVisible =
false;
   
}

   
/**
     * Make this circle visible. If it was already visible, do nothing.
     */
   
public void makeVisible()
    {
       
isVisible = true;
        draw
();
   
}
   
   
/**
     * Make this circle invisible. If it was already invisible, do nothing.
     */
   
public void makeInvisible()
    {
       
erase();
        isVisible =
false;
   
}
   
   
/**
     * Move the circle a few pixels to the right.
     */
   
public void moveRight()
    {
       
moveHorizontal(20);
   
}

   
/**
     * Move the circle a few pixels to the left.
     */
   
public void moveLeft()
    {
       
moveHorizontal(-20);
   
}

   
/**
     * Move the circle a few pixels up.
     */
   
public void moveUp()
    {
       
moveVertical(-20);
   
}

   
/**
     * Move the circle a few pixels down.
     */
   
public void moveDown()
    {
       
moveVertical(20);
   
}

   
/**
     * Move the circle horizontally by 'distance' pixels.
     *
@param distance distance en pixels
     */
   
public void moveHorizontal(int distance)
    {
       
erase();
        xPosition += distance;
        draw
();
   
}

   
/**
     * Move the circle vertically by 'distance' pixels.
     *
@param distance distance en pixels
     */
   
public void moveVertical(int distance)
    {
       
erase();
        yPosition += distance;
        draw
();
   
}

   
/**
     * Slowly move the circle horizontally by 'distance' pixels.
     *
@param distance distance en 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 circle vertically by 'distance' pixels.
     *
@param distance distance en 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.
     *
@param newDiameter nouveau diamètre
     */
   
public void changeSize(int newDiameter)
    {
       
erase();
        diameter = newDiameter;
        draw
();
   
}

   
/**
     * Change the color. Valid colors are "red", "yellow", "blue", "green",
     * "magenta" and "black".
     *
@param newColor nouvelle couleur
     */
   
public void changeColor(String newColor)
    {
       
color = newColor;
        draw
();
   
}

   
/**
     * Draw the circle with current specifications on screen.
     */
   
private void draw()
    {
       
if(isVisible) {
           
Canvas canvas = Canvas.getCanvas();
            canvas.draw
(this, color, new Ellipse2D.Double(xPosition, yPosition,
                                                          diameter, diameter
));
            canvas.wait
(10);
       
}
    }

   
/**
     * Erase the circle on screen.
     */
   
private void erase()
    {
       
if(isVisible) {
           
Canvas canvas = Canvas.getCanvas();
            canvas.erase
(this);
       
}
    }
}