我有一個程式，我必須使用內部 Timer 事件來以圓周運動旋轉星星。框架中有一個按鈕可以改變星星的方向，還有一個滑塊可以改變星星的旋轉速度。
這是我的主要課程
import javax.swing.JFrame;
public class Main {
public static void main(String args[]) {
// Making an instance of the class that makes the frame
MainFrame frame = new MainFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
frame.setVisible(true);
}
}
MainFrame 制作框架的類。
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
@SuppressWarnings("serial")
public class MainFrame extends JFrame{
private StarGraphics frameStar;
private JButton starToggle;
public JSlider starSpeed;
public MainFrame() {
// Setting some properties of the frame
setTitle("Star Moving with Internal Events");
setLayout(new BorderLayout());
// Initializing the panel which has rotating star
frameStar = new StarPainter(this);
// Adding the bottom toggle button and slider
addToggler();
}
// Getter for the slider value
public int sliderSpeed() {
return starSpeed.getValue();
}
// Adds Button to change the direction of the star
private void addToggler() {
// Adding another jpanel which has layout set to null so i can add button of my size
JPanel panel = new JPanel();
panel.setLayout(null);
panel.setPreferredSize(new Dimension(20,80));
panel.setBackground(Color.WHITE);
// Initializing button and its action listener to change star direction
starToggle = new JButton("Toggle");
starToggle.setBounds(190, 0, 80, 20);
starToggle.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == starToggle) {
frameStar.ChangeDirections();
}
}
});
// Adding button to panel
panel.add(starToggle);
// Adding slider to the panel
addSlider(panel);
// Adding panel to the main Panel at the bottom
add(panel, BorderLayout.SOUTH);
}
private void addSlider(JPanel panel) {
// Adding Slider and it's properties
starSpeed = new JSlider(JSlider.HORIZONTAL, 0, 20, 5);
starSpeed.setMajorTickSpacing(10);
starSpeed.setMinorTickSpacing(1);
starSpeed.setPaintTicks(true);
starSpeed.setPaintLabels(true);
starSpeed.setBounds(70,30,400, 45);
// Adding Slider-ChangeListener to change the rotation speed of the star
starSpeed.addChangeListener(new ChangeListener() { // anonymous inner class
// handle change in slider value
@Override
public void stateChanged(ChangeEvent e) {
frameStar.ChangeSpeed(starSpeed.getValue());
}
}
);
// Adding label besides the slider
JLabel label = new JLabel("Speed : ");
label.setBounds(10 , 10, 80, 80);
panel.add(label);
panel.add(starSpeed);
}
}
創建具有星形旋轉的面板的類
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
@SuppressWarnings("serial")
public class StarGraphics extends JPanel{
private boolean toggleDir = false;
private int speed = 10;
private Timer timer;
protected double angleOfStarRotation = 0;
public StarGraphics(JFrame frame) {
setPreferredSize(new Dimension(500, 470));
setBackground(Color.BLACK);
setLayout(new BorderLayout());
frame.add(this, BorderLayout.CENTER);
startTimer();
}
public void startTimer() {
timer = new Timer(speed, new ActionListener() {
public void actionPerformed(ActionEvent e){
// System.out.println(angleOfStarRotation);
if(!toggleDir) //rotates clockwise
angleOfStarRotation = angleOfStarRotation 1;
else //rotates counterclockwise
angleOfStarRotation = angleOfStarRotation - 1;
// if (angleOfStarRotation == 360 || angleOfStarRotation == -360) // If there is a full circle, it will reset the angle to zero
// angleOfStarRotation = 0;
repaint();
}});
timer.start();
}
public void ChangeSpeed(int newSpeed) {
this.speed = newSpeed;
timer.setDelay(speed);
}
public void ChangeDirections() {toggleDir = !toggleDir; }
}
還有一個將星星繪制到面板中的類
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.GeneralPath;
import java.security.SecureRandom;
import javax.swing.JFrame;
@SuppressWarnings("serial")
public class StarPainter extends StarGraphics{
private int[] starXPoints = {55, 67, 109, 73, 83, 55, 27, 37, 1, 43};
private int[] starYPoints = {0, 36, 36, 54, 96, 72, 96, 54, 36, 36};
GeneralPath starDesign = new GeneralPath();
public StarPainter(JFrame frame) {
super(frame);
}
public void drawStar(GeneralPath path) {
path.moveTo(starXPoints[0], starYPoints[0]);
for(int i=0; i<10; i )
path.lineTo(starXPoints[i], starYPoints[i]);
path.closePath();
}
public void starActions(Graphics2D g) {
int startAngle = 360;
// For Random Color
SecureRandom random = new SecureRandom();
// rotate around origin and draw stars in random colors
for (int count = 1; count <= 1; count )
{
double angle = startAngle - 90;
// rotate coordinate system
g.rotate(angleOfStarRotation * Math.PI / angle); //rotates as per the rotated angle //
// set random drawing color
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
// draw filled star
g.fill(starDesign);
// dispose the star
g.dispose();
}
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
drawStar(starDesign);
g2d.translate(250,150);
starActions(g2d);
}
}
運行代碼后，輸出會顯示一個帶有著色星的幀，它圍繞面板以圓周運動旋轉，但在旋轉 2 圈后，星的旋轉會自動減慢。有誰知道為什么會這樣？
uj5u.com熱心網友回復：
你的“核心”問題就在這里......
public void drawStar(GeneralPath path) {
path.moveTo(starXPoints[0], starYPoints[0]);
for(int i=0; i<10; i )
path.lineTo(starXPoints[i], starYPoints[i]);
path.closePath();
}
每次重新繪制組件時都會呼叫它，這意味著您正在向形狀添加新點，使其在每次繪制程序中變得無限復雜。
相反，只需在建構式中創建形狀......
public StarPainter() {
starDesign.moveTo(starXPoints[0], starYPoints[0]);
for (int i = 0; i < 10; i ) {
starDesign.lineTo(starXPoints[i], starYPoints[i]);
}
starDesign.closePath();
}
正如已經指出的那樣，您正在處理Graphics您沒有創建的背景關系。
如果您要更改背景關系的轉換，則應始終創建自己的副本，例如...
public void starActions(Graphics2D g) {
int startAngle = 360;
// For Random Color
SecureRandom random = new SecureRandom();
g = (Graphics2D) g.create();
// rotate around origin and draw stars in random colors
//for (int count = 1; count <= 1; count ) {
double angle = startAngle - 90;
// rotate coordinate system
g.rotate(angleOfStarRotation * Math.PI / angle); //rotates as per the rotated angle //
// set random drawing color
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
// draw filled star
g.fill(starDesign);
// dispose the star
g.dispose();
//}
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.translate(250, 150);
starActions(g2d);
g2d.dispose();
}
此外，傳遞JFrame對組件的參考...
public StarGraphics(JFrame frame) {
setPreferredSize(new Dimension(500, 470));
setBackground(Color.BLACK);
setLayout(new BorderLayout());
frame.add(this, BorderLayout.CENTER);
startTimer();
}
is a bad idea. The component has no need for, nor is it its responsibility too, interact with the frame. You're just exposing implementation detail unnecessarily.
Runnable example
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.GeneralPath;
import java.security.SecureRandom;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
MainFrame frame = new MainFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
frame.setVisible(true);
}
});
}
public class MainFrame extends JFrame {
private StarGraphics frameStar;
private JButton starToggle;
public JSlider starSpeed;
public MainFrame() {
// Setting some properties of the frame
setTitle("Star Moving with Internal Events");
setLayout(new BorderLayout());
// Initializing the panel which has rotating star
frameStar = new StarPainter();
add(frameStar);
// Adding the bottom toggle button and slider
addToggler();
}
// Getter for the slider value
public int sliderSpeed() {
return starSpeed.getValue();
}
// Adds Button to change the direction of the star
private void addToggler() {
// Adding another jpanel which has layout set to null so i can add button of my size
JPanel panel = new JPanel();
panel.setLayout(null);
panel.setPreferredSize(new Dimension(20, 80));
panel.setBackground(Color.WHITE);
// Initializing button and its action listener to change star direction
starToggle = new JButton("Toggle");
starToggle.setBounds(190, 0, 80, 20);
starToggle.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == starToggle) {
frameStar.ChangeDirections();
}
}
});
// Adding button to panel
panel.add(starToggle);
// Adding slider to the panel
addSlider(panel);
// Adding panel to the main Panel at the bottom
add(panel, BorderLayout.SOUTH);
}
private void addSlider(JPanel panel) {
// Adding Slider and it's properties
starSpeed = new JSlider(JSlider.HORIZONTAL, 0, 20, 5);
starSpeed.setMajorTickSpacing(10);
starSpeed.setMinorTickSpacing(1);
starSpeed.setPaintTicks(true);
starSpeed.setPaintLabels(true);
starSpeed.setBounds(70, 30, 400, 45);
// Adding Slider-ChangeListener to change the rotation speed of the star
starSpeed.addChangeListener(new ChangeListener() { // anonymous inner class
// handle change in slider value
@Override
public void stateChanged(ChangeEvent e) {
frameStar.ChangeSpeed(starSpeed.getValue());
}
}
);
// Adding label besides the slider
JLabel label = new JLabel("Speed : ");
label.setBounds(10, 10, 80, 80);
panel.add(label);
panel.add(starSpeed);
}
}
public class StarGraphics extends JPanel {
private boolean toggleDir = false;
private int speed = 10;
private Timer timer;
protected double angleOfStarRotation = 0;
public StarGraphics() {
setPreferredSize(new Dimension(500, 470));
setBackground(Color.BLACK);
setLayout(new BorderLayout());
startTimer();
}
public void startTimer() {
timer = new Timer(speed, new ActionListener() {
public void actionPerformed(ActionEvent e) {
// System.out.println(angleOfStarRotation);
if (!toggleDir) //rotates clockwise
{
angleOfStarRotation = angleOfStarRotation 1;
} else //rotates counterclockwise
{
angleOfStarRotation = angleOfStarRotation - 1;
}
System.out.println("tick");
// if (angleOfStarRotation == 360 || angleOfStarRotation == -360) // If there is a full circle, it will reset the angle to zero
// angleOfStarRotation = 0;
repaint();
}
});
timer.start();
}
public void ChangeSpeed(int newSpeed) {
this.speed = newSpeed;
timer.setDelay(speed);
}
public void ChangeDirections() {
toggleDir = !toggleDir;
}
}
public class StarPainter extends StarGraphics {
private int[] starXPoints = {55, 67, 109, 73, 83, 55, 27, 37, 1, 43};
private int[] starYPoints = {0, 36, 36, 54, 96, 72, 96, 54, 36, 36};
GeneralPath starDesign = new GeneralPath();
public StarPainter() {
starDesign.moveTo(starXPoints[0], starYPoints[0]);
for (int i = 0; i < 10; i ) {
starDesign.lineTo(starXPoints[i], starYPoints[i]);
}
starDesign.closePath();
}
public void starActions(Graphics2D g) {
int startAngle = 360;
// For Random Color
SecureRandom random = new SecureRandom();
g = (Graphics2D) g.create();
// rotate around origin and draw stars in random colors
//for (int count = 1; count <= 1; count ) {
double angle = startAngle - 90;
// rotate coordinate system
g.rotate(angleOfStarRotation * Math.PI / angle); //rotates as per the rotated angle //
// set random drawing color
g.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));
// draw filled star
g.fill(starDesign);
// dispose the star
g.dispose();
//}
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.translate(250, 150);
starActions(g2d);
g2d.dispose();
}
}
}
轉載請註明出處，本文鏈接：https://www.uj5u.com/net/429887.html
上一篇：MacOSX上的JTable多選