home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Chip 2005 February
/
CMCD0205.ISO
/
Software
/
Freeware
/
Programare
/
bluej
/
bluejsetup-203.exe
/
{app}
/
examples
/
shapes
/
Triangle.java
< prev
Wrap
Text File
|
2004-12-19
|
3KB
|
196 lines
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;
/**
* 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);
}
}
}