feat(BulletAnim)

package controller;

import model.game.Game;

import io.vavr.Tuple3;

import model.game.Msg;

import view.AppFrame;

import javax.swing.*;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.util.ArrayDeque;

import java.util.Date;

import java.util.Deque;

import java.util.Random;

public class BulletAnim extends Thread {

    public final int BULLET_FONT_SIZE = 10;

    public final Font BULLET_FONT = new Font("Rockwell", Font.PLAIN, BULLET_FONT_SIZE);

    public final double BULLET_SPEED = 3.1;

    private int l = 0;  // 最小序号，序号区间左端

    private int r = 0; // 最大序号+1，序号区间右端excluded

    private Deque<Tuple3<Integer, Long, JLabel>> bulletQueue = new ArrayDeque<>();

    // 每个元组有三个元素：第一是对应msg在msgList中的序号；第二是发出时间；第三是JLabel元素

    private Random random = new Random();

    @Override

    public void run() {

        super.run();

        while (true) {

            for (Msg msg: Game.instance.getMsgList()){

                drawBullet(msg);

            // 更新bulletQueue，尽可能减少GUI元素销毁或新建的次数

            // 1. 首先寻找尾部能加入的新元素，右界右移

            while (r < Msg.msgList.size() && canShowBullet(Msg.msgList.get(r))) r++;

            // 左界右移

            while (l < Msg.msgList.size() && !canShowBullet(Msg.msgList.get(l))) l++;

            // 2. 出界的元素从头部出来后重新从尾部加入

            while (true) {

                Tuple3<Integer, Long, JLabel> head = bulletQueue.getFirst();

                Tuple3<Integer, Long, JLabel> tail = bulletQueue.getLast();

                if (!(head._1 < l && tail._1 + 1 < r)) break;

                bulletQueue.pop();

                bulletQueue.add(new Tuple3<>(tail._1 + 1, Msg.msgList.get(tail._1 + 1).time().getTime(), head._3));

            }

            // 3. 销毁左边多余的元组

            while (bulletQueue.getFirst()._1 < l) {

                AppFrame.instance.getContentPane().remove(bulletQueue.getFirst()._3);

                bulletQueue.pop();

            }

            // 4. 右边加入新的元组

            while (true) {

                Tuple3<Integer, Long, JLabel> tail = bulletQueue.getLast();

                if (!(tail._1 + 1 < r)) break;

                Tuple3<Integer, Long, JLabel> newTuple = new Tuple3<>(

                    tail._1 + 1,

                    Msg.msgList.get(tail._1 + 1).time().getTime(),

                    newBulletLabel(Msg.msgList.get(tail._1 + 1))

                );

                bulletQueue.add(newTuple);

                AppFrame.instance.getContentPane().add(newTuple._3);

            }

            // 迭代每一个元组，画弹幕

            bulletQueue.forEach(this::drawBullet);

            try {

                sleep(50);

            } catch (InterruptedException ignored) {

        }

    }

    public void drawBullet(Msg msg){

        //TODO: drawBullet

    /**

     * 创建新的弹幕，需要传入这个弹幕所显示的消息对象

     * @param msg 消息

     */

    private JLabel newBulletLabel(Msg msg){

        JLabel jLabel = new JLabel();

        jLabel.setOpaque(false);

        jLabel.setSize(evalLength(msg), BULLET_FONT_SIZE);

        jLabel.setFont(new Font("Rockwell", Font.BOLD, BULLET_FONT_SIZE));

        jLabel.setLocation(

            AppFrame.instance.getContentPane().getWidth(),

            random.nextInt(AppFrame.instance.getContentPane().getHeight() - BULLET_FONT_SIZE)

        );

        jLabel.setVisible(true);

        return jLabel;

    }

        JPanel bullet = new JPanel();

        JTextArea bulletText = new JTextArea();

        bullet.add(bulletText);

    private void drawBullet(Tuple3<Integer, Long, JLabel> tuple) {

        Msg msg = Msg.msgList.get(tuple._1);

        tuple._3.setText(msg.content());

        tuple._3.setLocation(evalX(msg), tuple._3.getY());

        tuple._3.repaint();

    }

        bullet.setOpaque(false);

        bulletText.setSize(50,20);

        bulletText.setFont(new Font("Rockwell", Font.BOLD, 20));

        bullet.setVisible(true);

        Timer draw = new Timer(100, new AbstractAction() {

            @Override

            public void actionPerformed(ActionEvent e) {

                int x = 400;

                bulletText.setText(String.valueOf(msg));

                while (x >= 0) {

                    x -= 20;

                    bullet.setLocation(x, 200);

    /**

     * 判断一个弹幕是否需要显示

     * <br/>

     * <br/>设某个消息的发出时间为T0，当前时间为T，屏幕宽度为w，

     * <br/>那么弹幕在T0时刻的左端x坐标为w;

     * <br/>左端x坐标关于T的函数：x - w = -v * (T - T0)

     * <br/>因此弹幕暴露在屏幕中的条件是： -L &lt; x &lt; w

     */

    public boolean canShowBullet(Msg msg) {

        return -evalLength(msg) < evalX(msg) && evalX(msg) < AppFrame.instance.getContentPane().getWidth();

    }

    /**

     * 计算弹幕左端x坐标

     * <br/>

     * <br/>设某个消息的发出时间为T0，当前时间为T，屏幕宽度为w，

     * <br/>那么弹幕在T0时刻的左端x坐标为w;

     * <br/>左端x坐标关于T的函数：x - w = -v * (T - T0)

     * @param msg 消息

     * @return 左端x坐标

     */

    private int evalX(Msg msg){

        long now = new Date().getTime();

        long msgTime = msg.time().getTime();

        return (int)(AppFrame.instance.getContentPane().getWidth() - BULLET_SPEED * (now - msgTime));

    }

        });

    /**

     * <br/>计算弹幕的像素长度

     * <br/>

     * <br/>不确定这种方式对不对，早晚有一天会要修改的

     * @param msg 消息

     * @return 长度

     */

    private int evalLength(Msg msg){

        return msg.content().length() * BULLET_FONT_SIZE;   //不确定这种长度计算方式对不对

    }

}