[英]Stop Applet from flickering
I've got a problem with my Applet game in Java. 我的Java Applet游戏出现问题。 It's flickering a lot when I run it.
当我运行它时,它经常闪烁。 I have tried double buffering, but it didn't help.
我曾尝试过双缓冲,但没有帮助。 Here is a short coded version that shows the flickering...
这是一个简短的编码版本,显示闪烁...
public class Test extends JApplet implements ActionListener {
JButton start;
int delay;
Timer tm;
// Falling balls
int n; // Total balls
Ball[] ball; // Array with the balls in
int score;
// The amount of balls falling at the same time (increases by one every
// 10:th score)
int ballNr;
// Comment to the game
String comment;
public void init() {
this.setLayout(null);
this.setSize(600, 500);
this.getContentPane().setBackground(Color.cyan);
this.setFocusable(true);
score = 0;
ballNr = 3;
comment = "Avoid the balls!";
// Buttons
start = new JButton("START");
add(start);
start.setBounds(0, 400, 200, 100);
start.addActionListener(this);
// The timer
delay = 12;
tm = new Timer(delay, this);
// The falling balls
n = 12; // Number of balls in total
ball = new Ball[n];
// Declaring twelve new instances of the ball-object with a
// "reference array"
for (int i = 0; i < n; i++) {
ball[i] = new Ball();
}
}
// Paint-method //
public void paint(Graphics g) {
super.paint(g);
// Every 10:th score, the game adds one ball until you reach 100 =
// win! (ballNr + (int)(score * 0.1) -> ballNr increases by one
// every 10:th score
for (int i = 0; i < ballNr + (int) (score * 0.1); i++) {
// Score can't be higher than 100
if (score < 100) {
g.setColor(ball[i].getCol());
g.fillOval(ball[i].getXLoc(), ball[i].getYLoc(),
ball[i].getSize(), ball[i].getSize());
}
}
// Draw the score and the comment
g.setColor(Color.black);
g.setFont(new Font("Arial", Font.BOLD, 24));
g.drawString("SCORE: " + score, 440, 40);
g.setColor(Color.red);
g.setFont(new Font("Arial", Font.BOLD + Font.ITALIC, 28));
g.drawString(comment, 0, 40);
}
// ACTIONLISTENER //
public void actionPerformed(ActionEvent e) {
if (e.getSource() == start) {
tm.start();
this.requestFocusInWindow(); // Make the runner component have focus
}
// Every 10:th score, the game adds one ball until you reach 100 =
// win! (ballNr + (int)(score * 0.1) -> ballNr increases by one
// every 10:th score
for (int i = 0; i < ballNr + (int) (score * 0.1); i++) {
// Score can't pass 100, because then you have won the game
if (score < 100) {
ball[i].setYLoc(ball[i].getYLoc() + ball[i].getVel());
}
}
// If any ball is out of bounds (then the score increases by one)
for (int i = 0; i < n; i++) {
if (outOfBounds(ball[i])) {
ball[i] = new Ball();
}
}
repaint();
}
// If the ball is out of the screen
public boolean outOfBounds(Ball ball) {
if (ball.getYLoc() >= 500) {
score++;
return true;
} else {
return false;
}
}
// Updates new balls
public void updateBalls() {
for (int i = 0; i < n; i++) {
ball[i] = new Ball();
}
}
}
AND 和
public class Ball {
// Private variables
private Random r; // Generating random positions and
// sizes;
private int size; // Size of the ball
private int vel; // Ball velocity
private int nrOfCol; // Color code (see ballColor-method)
private Color col;
private int xLoc;
private int yLoc;
// Constructor
public Ball() {
r = new Random();
size = r.nextInt(40) + 10; // 10px - 50 px
vel = r.nextInt(6) + 1; // Speed btw 1-5 px/delay
nrOfCol = r.nextInt(8) + 1; // Specific nr from 1-9
col = ballColor();
xLoc = r.nextInt(550);
yLoc = 0;
}
public Ball(int xPos, int yPos, int size, int vel, Color col) {
this.xLoc = xPos;
this.yLoc = yPos;
this.size = size;
this.vel = vel;
this.col = col;
}
// A method to generate different colors of the balls
public Color ballColor() {
Color col;
switch (nrOfCol) {
case 1:
col = Color.black;
break;
case 2:
col = Color.red;
break;
case 3:
col = Color.green;
break;
case 4:
col = Color.yellow;
break;
case 5:
col = Color.pink;
break;
case 6:
col = Color.magenta;
break;
case 7:
col = Color.white;
break;
case 8:
col = Color.orange;
break;
case 9:
col = Color.blue;
break;
default:
col = Color.black;
// All colors except cyan as it is the background color
}
return col;
}
// Getters & setters
public int getXLoc() {
return xLoc;
}
public int getYLoc() {
return yLoc;
}
public void setYLoc(int y) {
yLoc = y;
}
public int getSize() {
return size;
}
public int getVel() {
return vel;
}
public Color getCol() {
return col;
}
}
I hope you can help me out as this is a very annoying issue I get on all my applets with animations. 我希望您能帮助我,因为这是我所有带有动画的小程序上都遇到的非常烦人的问题。 I would really appreciate help from you guys!
非常感谢你们的帮助!
Don't use null
layout at all instead there are lots of Layout Manager that can be used. 根本不要使用
null
布局,而是可以使用很多布局管理器。
Use a container to add all the component in it and add it finally in the root container of JApplet
. 使用容器将所有组件添加到其中,最后将其添加到
JApplet
的根容器中。
Use JPanel
and override paintComponent()
for custom panting that will eliminate the flickering as well. 使用
JPanel
并覆盖paintComponent()
进行自定义气调,这也将消除闪烁。
paint
method is a heavy operation that does lots of things in the background. paint
方法是一项繁重的操作,它会在后台执行很多操作。
Read Difference between paint, paintComponent and paintComponents in Swing 阅读Swing中paint,paintComponent和paintComponents之间的区别
Please have a look at Painting in AWT and Swing that describes it in detail. 请查看详细描述它的AWT和Swing中的绘画 。
It's worth reading How paint method works? 值得一读的是绘画方法是如何工作的?
Swing programs should override
paintComponent()
instead of overridingpaint()
.Swing程序应该重写
paintComponent()
而不是重写paint()
。 Although the API allows it, there is generally no reason to overridepaintBorder()
orpaintComponents()
(and if you do, make sure you know what you're doing!).尽管该API允许这样做,但是通常没有理由覆盖
paintBorder()
或paintComponents()
(如果这样做,请确保您知道自己在做什么!)。 This factoring makes it easier for programs to override only the portion of the painting which they need to extend.这种分解使程序更容易仅覆盖需要扩展的绘画部分。
Sample code: 样例代码:
JPanel panel = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
// custom painting code goes here
}
}
Here is the code with the fix I suggested in comment. 这是我在注释中建议的修复程序代码。
Don't paint to a top level container like
JApplet
.不要在
JApplet
类的顶级容器上绘画。 Instead do custom painting in aJPanel
and override thepaintComponent(..)
method instead ofpaint()
.而是在
JPanel
进行自定义绘制,并重写paintComponent(..)
方法而不是paint()
。
Note that a JComponent
is double buffered by default, whereas a top-level container like JApplet
typically isn't. 请注意,默认情况下,
JComponent
是双缓冲的,而像JApplet
这样的顶级容器通常不是。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Random;
/* <applet code=TestApplet width=600 height=500></applet> */
public class TestApplet extends JApplet {
@Override
public void init() {
add(new PlayingArea());
}
}
class PlayingArea extends JPanel implements ActionListener {
JButton start;
int delay;
Timer tm;
// Falling balls
int n; // Total balls
Ball[] ball; // Array with the balls in
int score;
// The amount of balls falling at the same time (increases by one every
// 10:th score)
int ballNr;
// Comment to the game
String comment;
public PlayingArea() {
setBackground(Color.cyan);
setFocusable(true);
score = 0;
ballNr = 3;
comment = "Avoid the balls!";
// Buttons
start = new JButton("START");
add(start);
start.setBounds(0, 400, 200, 100);
start.addActionListener(this);
// The timer
delay = 12;
tm = new Timer(delay, this);
// The falling balls
n = 12; // Number of balls in total
ball = new Ball[n];
// Declaring twelve new instances of the ball-object with a
// "reference array"
for (int i = 0; i < n; i++) {
ball[i] = new Ball();
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(600,500);
}
// Paint-method //
public void paintComponent(Graphics g) {
super.paintComponent(g);
// Every 10:th score, the game adds one ball until you reach 100 =
// win! (ballNr + (int)(score * 0.1) -> ballNr increases by one
// every 10:th score
for (int i = 0; i < ballNr + (int) (score * 0.1); i++) {
// Score can't be higher than 100
if (score < 100) {
g.setColor(ball[i].getCol());
g.fillOval(ball[i].getXLoc(), ball[i].getYLoc(),
ball[i].getSize(), ball[i].getSize());
}
}
// Draw the score and the comment
g.setColor(Color.black);
g.setFont(new Font("Arial", Font.BOLD, 24));
g.drawString("SCORE: " + score, 440, 40);
g.setColor(Color.red);
g.setFont(new Font("Arial", Font.BOLD + Font.ITALIC, 28));
g.drawString(comment, 0, 40);
}
// ACTIONLISTENER //
public void actionPerformed(ActionEvent e) {
if (e.getSource() == start) {
tm.start();
this.requestFocusInWindow(); // Make the runner component have focus
}
// Every 10:th score, the game adds one ball until you reach 100 =
// win! (ballNr + (int)(score * 0.1) -> ballNr increases by one
// every 10:th score
for (int i = 0; i < ballNr + (int) (score * 0.1); i++) {
// Score can't pass 100, because then you have won the game
if (score < 100) {
ball[i].setYLoc(ball[i].getYLoc() + ball[i].getVel());
}
}
// If any ball is out of bounds (then the score increases by one)
for (int i = 0; i < n; i++) {
if (outOfBounds(ball[i])) {
ball[i] = new Ball();
}
}
repaint();
}
// If the ball is out of the screen
public boolean outOfBounds(Ball ball) {
if (ball.getYLoc() >= 500) {
score++;
return true;
} else {
return false;
}
}
// Updates new balls
public void updateBalls() {
for (int i = 0; i < n; i++) {
ball[i] = new Ball();
}
}
}
class Ball {
// Private variables
private Random r; // Generating random positions and
// sizes;
private int size; // Size of the ball
private int vel; // Ball velocity
private int nrOfCol; // Color code (see ballColor-method)
private Color col;
private int xLoc;
private int yLoc;
// Constructor
public Ball() {
r = new Random();
size = r.nextInt(40) + 10; // 10px - 50 px
vel = r.nextInt(6) + 1; // Speed btw 1-5 px/delay
nrOfCol = r.nextInt(8) + 1; // Specific nr from 1-9
col = ballColor();
xLoc = r.nextInt(550);
yLoc = 0;
}
public Ball(int xPos, int yPos, int size, int vel, Color col) {
this.xLoc = xPos;
this.yLoc = yPos;
this.size = size;
this.vel = vel;
this.col = col;
}
// A method to generate different colors of the balls
public Color ballColor() {
Color col;
switch (nrOfCol) {
case 1:
col = Color.black;
break;
case 2:
col = Color.red;
break;
case 3:
col = Color.green;
break;
case 4:
col = Color.yellow;
break;
case 5:
col = Color.pink;
break;
case 6:
col = Color.magenta;
break;
case 7:
col = Color.white;
break;
case 8:
col = Color.orange;
break;
case 9:
col = Color.blue;
break;
default:
col = Color.black;
// All colors except cyan as it is the background color
}
return col;
}
// Getters & setters
public int getXLoc() {
return xLoc;
}
public int getYLoc() {
return yLoc;
}
public void setYLoc(int y) {
yLoc = y;
}
public int getSize() {
return size;
}
public int getVel() {
return vel;
}
public Color getCol() {
return col;
}
}
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