我创建了一个窗口，其中有一个大的JPanel占据了将用于为一组烟花制作动画的区域的大部分区域。我有一个私有内部类AnimationPanel，它扩展了JPanel。我已重写paintComponent（）以使用缓冲图像作为背景。按下开始按钮后，将运行模拟，该模拟将为烟花组设置动画。现在，此模拟将位置输出到控制台，并生成一个名为snapshot的集合，其中包含特定时间点的所有烟花。
目前，我已经成功绘制了背景和一个小矩形来代表发射管，但是当我尝试从快照中绘制烟花时，没有任何东西出现。此时我并不关心动画（仍在学习如何使用Timer类进行此操作），但我需要知道绘制将起作用，所以我只是想绘制快照。我在获取快照后在模拟结束时重新绘制animationPanel。
私有内部类AnimationPanel
private class AnimationPanel extends JPanel {
private BufferedImage background;
public AnimationPanel() {
super();
try {
background = ImageIO.read(new File("background.jpg"));
} catch(IOException error) {
error.printStackTrace();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(background,0,0,getWidth(),getHeight(),this); //this shows up
g.setColor(Color.RED);
g.fillRect(getWidth()/2, getHeight()-30, 10, 30); //this shows up
paintFireWorks(g); //this doesn't show up
}
private void paintFireWorks(Graphics g) {
if(snapshot != null) {
for(Firework item: snapshot) {
double[] position = item.getPosition();
if(item instanceof Star){
int x = (int)Math.round(position[0])+animationPanel.getWidth()/2;
int y = animationPanel.getHeight()-(int)Math.round(position[1]);
int r = ((Star) item).getRenderSize();
g.fillOval(x,y,r,r);
} else if(item instanceof Spark){
int x1 = (int)Math.round(position[0])+animationPanel.getWidth()/2;
int x2 = (int)Math.round(position[0])-((Spark)item).getRenderSize();
int y1 = animationPanel.getHeight()-(int)Math.round(position[1]);
int y2 = animationPanel.getHeight()-(int)Math.round(position[1])+((Spark)item).getRenderSize();
g.drawLine(x1,y1,x2,y2);
}
}
}
}
}
整个FireWorksWindow类：
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.*;
@SuppressWarnings("serial")
public class FireWorksWindow extends JFrame {
//DIMENSIONS AND POSITIONS
private final int STARTING_POS_X = 1600;
private final int STARTING_POS_Y = 100;
//CONTAINERS AND COMPONENTS
private AnimationPanel animationPanel;
private JPanel controlPanel, sliderPanel;
private Box controlBox;
private JLabel windSliderLabel, angleSliderLabel;
private JSlider windSpeed, launchAngle;
private JButton startButton, pauseButton, exitButton;
//TIMER
private Timer animationTimer;
//COLLECTIONS
ArrayList<Particle> fireworks;
ArrayList<Particle> snapshot;
//CONSTRUCTOR
public FireWorksWindow() {
setTitle("Roman Candle Animation");
setLocation(STARTING_POS_X,STARTING_POS_Y);
setDefaultCloseOperation(EXIT_ON_CLOSE);
sliderPanel = new JPanel();
GridBagLayout sliderGrid = new GridBagLayout();
sliderPanel.setLayout(sliderGrid);
initSliders();
initLabels();
addComponent(sliderGrid, windSliderLabel, 1,1,new Insets(5,10,5,10));
addComponent(sliderGrid, angleSliderLabel, 1,2,new Insets(5,10,5,10));
addComponent(sliderGrid, windSpeed, 2,1,new Insets(5,10,5,10));
addComponent(sliderGrid, launchAngle, 2,2,new Insets(5,10,5,10));
controlPanel = new JPanel();
controlPanel.setLayout(new BoxLayout(controlPanel,BoxLayout.X_AXIS));
initButtons();
initControlBox();
controlPanel.add(controlBox);
controlPanel.setBorder(BorderFactory.createLineBorder(Color.MAGENTA , 3 ));
animationPanel = new AnimationPanel();
animationPanel.setSize(new Dimension(750,500));
animationPanel.setMinimumSize(new Dimension(animationPanel.getWidth(),animationPanel.getHeight()));
animationPanel.setPreferredSize(new Dimension(animationPanel.getWidth(),animationPanel.getHeight()));
add(animationPanel,BorderLayout.CENTER);
add(controlPanel,BorderLayout.SOUTH);
pack();
setMinimumSize(new Dimension(getWidth(),getHeight()));
sliderPanel.setMaximumSize(new Dimension(sliderPanel.getWidth(), sliderPanel.getHeight()));
}
//CONVENIENCE METHODS
private void addComponent(GridBagLayout layout, Component component, int row, int column, Insets padding) {
GridBagConstraints constraints = new GridBagConstraints();
constraints.gridx = column;
constraints.gridy = row;
constraints.insets = padding;
layout.setConstraints(component, constraints);
sliderPanel.add(component);
}
private void initLabels() {
windSliderLabel = new JLabel("Wind Speed");
angleSliderLabel = new JLabel("Launch Angle");
}
private void initSliders() {
windSpeed = new JSlider(-20,20);
windSpeed.setMajorTickSpacing(10);
windSpeed.setMinorTickSpacing(5);
windSpeed.setPaintTicks(true);
windSpeed.setPaintLabels(true);
launchAngle = new JSlider(-15,15);
launchAngle.setMajorTickSpacing(5);
launchAngle.setMinorTickSpacing(1);
launchAngle.setPaintTicks(true);
launchAngle.setPaintLabels(true);
}
private void initButtons() {
startButton = new JButton("Start");
startButton.addActionListener(new StartHandler());
pauseButton = new JButton("Pause");
pauseButton.addActionListener(new PauseHandler());
exitButton = new JButton("Exit" );
exitButton.addActionListener(new ExitHandler());
}
private void initControlBox() {
controlBox = Box.createHorizontalBox();
controlBox.add(Box.createHorizontalStrut(10));
controlBox.add(sliderPanel);
controlBox.add(Box.createHorizontalStrut(30));
controlBox.add(startButton);
controlBox.add(Box.createHorizontalStrut(10));
controlBox.add(pauseButton);
controlBox.add(Box.createHorizontalGlue());
controlBox.add(Box.createHorizontalStrut(10));
controlBox.add(Box.createHorizontalGlue());
controlBox.add(exitButton);
controlBox.add(Box.createHorizontalStrut(10));
}
//ACTION LISTENERS
public class WindAdjustListener implements ActionListener{
public void actionPerformed(ActionEvent e) {
}
}
public class AngleAdjustListener implements ActionListener{
public void actionPerformed(ActionEvent e) {
}
}
public class StartHandler implements ActionListener {
public void actionPerformed(ActionEvent event) {
System.out.println("START Pressed");
startButton.setText("Reset");
repaint();
runAnimation();
startButton.setText("Start");
}
}
public class PauseHandler implements ActionListener {
public void actionPerformed(ActionEvent event) {
System.out.println("PAUSE Pressed");
}
}
public class ExitHandler implements ActionListener {
public void actionPerformed(ActionEvent event) {
if(animationTimer != null)
if(animationTimer.isRunning())
animationTimer.stop();
System.exit(0);
}
}
public class AnimationClock implements ActionListener {
public void actionPerformed(ActionEvent arg0) {
}
}
//ACCESSORS
public double[] getSliderValues() {
double[] sliders = new double[2];
sliders[0] = windSpeed.getValue();
sliders[1] = launchAngle.getValue();
return sliders;
}
//OTHER METHODS
public void runAnimation() {
double[] inputs = getSliderValues();
double wind = inputs[0];
double launchAngle = inputs[1];
double timeInterval = 0.05; // seconds
ParticleManager manager = null;
try {
manager = new ParticleManager(wind, launchAngle);
} catch (EnvironmentException except) {
System.out.println(except.getMessage());
return;
} catch (EmitterException except) {
System.out.println(except.getMessage());
return;
}
System.out.println("Counts:");
System.out.println("time\tStars\tSparks\tLaunchSparks");
double time = 0;
manager.start(time);
fireworks = manager.getFireworks(time);
do {
//if (time % 0.5 == 0)
showTypesCount(fireworks, time);
if (Math.abs(time - 2.0) < timeInterval)
snapshot = fireworks;
time += timeInterval;
fireworks = manager.getFireworks(time);
} while (fireworks.size() > 0);
showFireworks(snapshot, 2.0);
animationPanel.repaint();
}
public void showFireworks(ArrayList<Particle> fireworks, double time) {
if (fireworks == null)
return;
System.out.printf("\nAt time%5.2f seconds:\n", time);
System.out.println("Type\t\tPosition (metres)");
for (Particle firework : fireworks)
System.out.println(firework);
}
public void showTypesCount(ArrayList<Particle> fireworks, double time) {
int starCount = 0;
int sparkCount = 0;
int launchSparkCount = 0;
for (Particle firework : fireworks) {
if (firework instanceof Star)
starCount++;
else if (firework instanceof LaunchSpark)
launchSparkCount++;
else
sparkCount++;
}
System.out.printf("%5.2f\t", time);
System.out.println(starCount + "\t" + sparkCount + "\t" + launchSparkCount);
}
private class AnimationPanel extends JPanel {
private BufferedImage background;
public AnimationPanel() {
super();
try {
background = ImageIO.read(new File("background.jpg"));
} catch(IOException error) {
error.printStackTrace();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(background,0,0,getWidth(),getHeight(),this); //this shows up
g.setColor(Color.RED);
g.fillRect(getWidth()/2, getHeight()-30, 10, 30); //this shows up
paintFireWorks(g); //this doesn't show up
}
private void paintFireWorks(Graphics g) {
if(snapshot != null) {
for(Firework item: snapshot) {
double[] position = item.getPosition();
if(item instanceof Star){
int x = (int)Math.round(position[0])+animationPanel.getWidth()/2;
int y = animationPanel.getHeight()-(int)Math.round(position[1]);
int r = ((Star) item).getRenderSize();
g.fillOval(x,y,r,r);
} else if(item instanceof Spark){
int x1 = (int)Math.round(position[0])+animationPanel.getWidth()/2;
int x2 = (int)Math.round(position[0])-((Spark)item).getRenderSize();
int y1 = animationPanel.getHeight()-(int)Math.round(position[1]);
int y2 = animationPanel.getHeight()-(int)Math.round(position[1])+((Spark)item).getRenderSize();
g.drawLine(x1,y1,x2,y2);
}
}
}
}
}
}
有关为什么烟花图画没有出现的任何想法？我试图适应这个答案（Dynamic Graphics Object Painting）和这个（panel with image background and mouse draw）中显示的方法，但没有成功。仍然坚持背景和矩形。
答案 0 :(得分：2)
基于此...
public class StartHandler implements ActionListener {
public void actionPerformed(ActionEvent event) {
System.out.println("START Pressed");
startButton.setText("Reset");
repaint();
runAnimation();
startButton.setText("Start");
}
}
您正在事件调度线程的上下文中调用runAnimation
在你runAnimation方法中，你可以这样做......
do {
//...
} while (fireworks.size() > 0);
阻止EDT并阻止处理新事件，包括重新绘制请求
一个简单的解决方案是使用Swing Timer，它允许你将一小部分等待卸载到后台但是在EDT的上下文中触发......