ball.java

j2me源代码

package pinball;

import javax.microedition.lcdui.Graphics;

/**
 *
 * <p>Title: 弹球</p>
 *
 * <p>Description: 该类实现了弹球的显示和属性的维护，包括弹球的半径，坐标。
 *                 此外，该类还实现了弹球的自绘功能。</p>
 *
 */
public class Ball extends Sprite {
    private int dx;		//x方向的坐标增量
    private int dy;		//y方向的坐标增量
    private int Ox;   //原点x坐标
    private int Oy;   //原点y坐标
    public static final int RADIUS = Math.max(2, Screen.width / 55);  //直径
    private ThreeDColor color;
    private ThreeDColor brighter;
    private ThreeDColor darker;
    private int counter;
    private int offset;

    public Ball(int x, int y, int dx, int dy) {
        moveTo(x, y);
        setSteps(dx, dy);

        offset = 0;
        width = 2 * RADIUS;
        height = 2 * RADIUS;
        this.dx = dx;
        this.dy = dy;
        Ox = Oy = 0;
        color = ThreeDColor.red;
        brighter = color.brighter();
        darker = color.darker();
    }

    public void setSteps(int dx, int dy) {
        this.dx = dx;
        this.dy = dy;
    }

    public int getXStep() {
        return dx;
    }

    public int getYStep() {
        return dy;
    }

    public void move() {
        x = x + dx + Ox;
        y = y + dy + Oy;
        Ox = Oy = 0;
    }

    /**
     * 水平反弹
     */
    public void bounceHorizontal() {
        dx = -dx;

        if (RandomNum.getRandomInt(0, 1000) < 70) {
            Ox = dx < 0 ? -1 : 1;
        }
    }

    /**
     * 竖直反弹
     */
    public void bounceVertical() {
        dy = -dy;

        if (RandomNum.getRandomInt(0, 1000) < 70) {
            Oy = dy < 0 ? -1 : 1;
        }
    }

    /**
     * 一般反弹
     */
    public void bounce(Sprite other) {
        int cx, cy;

        cx = getCenterX();
        cy = getCenterY();

        if (dx < 0) {  //原来向左移动
            if (cy >= other.y && cy < other.y + other.height
                && x < other.x + other.width) {
                dx = Math.abs(dx);  //反弹后向右
            }
        } else {			//原来向右移动
            if (cy >= other.y && cy < other.y + other.height
                && x + width >= other.x) {
                dx = -Math.abs(dx);  //反弹后向左
            }
        }

        if (dy < 0) {	//原来向上移动
            if (cx >= other.x && cx < other.x + other.width
                && y < other.y + other.height) {
                dy = Math.abs(dy);  //反弹后向下移动
            }
        } else {		//原来向下移动
            if (cx >= other.x && cx < other.x + other.width
                && y + height >= other.y) {
                dy = -Math.abs(dy);		//反弹后向上移动
            }
        }

				//以一定的概率偏离原来的方向，防止形成"乒乓效应"
        if (RandomNum.getRandomInt(0, 1000) < 70) {
            Ox = dx < 0 ? -1 : 1;
        }

        if (RandomNum.getRandomInt(0, 1000) < 70) {
            Oy = dy < 0 ? -1 : 1;
        }
    }

    /**
     * 绘制阴影
     */
    public void paintShadow(Graphics g) {
        g.setColor(ThreeDColor.black.getRGB());
        g.fillArc(x + shadow, y + shadow, width, height, 0, 360);
    }

    /**
     * 自绘函数
     */
    public void paint(Graphics g) {
        if (++counter == 6) {
            counter = 0;		//循环计数
            offset = 1 - offset;  //决定阴影的偏移方向
        }

        g.setColor(color.getRGB());
        g.fillArc(x, y, width, height, 0, 360);
        g.setColor(brighter.getRGB());
        g.drawArc(x + 2, y + 2, width - 4, height - 4, 180 + offset, -90);
        g.setColor(darker.getRGB());
        g.drawArc(x, y, width, height, 0, -90);
    }

}