spark.java

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//
// Copyright 2002 Nokia Mobile Phones Ltd.
//
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// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE
// OR TRADE PRACTICE, RELATING TO THE SOURCE CODE OR ANY WARRANTY OTHERWISE
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// Furthermore, information provided in this source code is preliminary,
// and may be changed substantially prior to final release. Nokia Mobile
// Phones Ltd. retains the right to make changes to this source code at
// any time, without notice. This source code is provided for informational
// purposes only.
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// Sun Microsystems Inc.
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// granted to the Licensee to download, print, reproduce and modify the
// source code. The licensee has the right to market, sell, distribute and
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package example.fireworks;

import javax.microedition.lcdui.*;


class Spark
    extends ListItem
{
    private static final int DRAG_FACTOR =
                            (1 << FireworksCanvas.FIXED_POINT_SHIFT) / 10;
    private static final int GRAVITATIONAL_ACCELERATION =
                            (1 << FireworksCanvas.FIXED_POINT_SHIFT) / 10;
    
    private int x;
    private int y;
    private int oldX;
    private int oldY;
    private int vx;
    private int vy;
    private final int colour;
    private int ticksToLive;


    Spark(int x, int y,
                 int vx, int vy,
                 int colour,
                 int ticksToLive)
    {
        this.x = x;
        this.y = y;
        oldX = x;
        oldY = y;
        this.vx = vx;
        this.vy = vy;
        this.colour = colour;
        this.ticksToLive = ticksToLive;
    }


    void tick()
    {
        if (--ticksToLive <= 0)
        {
            remove();
        }
        else
        {
            oldX = x;
            oldY = y;

            x += vx;
            y += vy;

            vx -= (vx * DRAG_FACTOR) >> FireworksCanvas.FIXED_POINT_SHIFT;
            vy -= (vy * DRAG_FACTOR) >> FireworksCanvas.FIXED_POINT_SHIFT;
            vy += GRAVITATIONAL_ACCELERATION;
        }
    }


    void draw(Graphics g)
    {
        g.setColor(colour);
        g.drawLine(x >> FireworksCanvas.FIXED_POINT_SHIFT,
                   y >> FireworksCanvas.FIXED_POINT_SHIFT,
                   oldX >> FireworksCanvas.FIXED_POINT_SHIFT,
                   oldY >> FireworksCanvas.FIXED_POINT_SHIFT);
    }
}