为什么在错误的地方画线? [英] Why does it draw lines in the wrong place?
问题描述
我对此有问题...当我画一条线时，字符跟随我画的那条线，但是计算机在其他地方画了一条线:
I have a problem with this... When I draw a line the character follows the line I drew but the computer paints a line somewhere else:
那么有人知道发生了什么吗?
My code:
So does anyone know what is going on?
My code:
@SuppressWarnings({"serial","rawtypes","unchecked"})
public class someGame extends JFrame implements MouseListener, KeyListener{
ArrayList lines = new ArrayList();
Point2D.Double start;
final Color BROWN = new Color(156,93,82);
Slider thread;
Rectangle cow = null;
boolean drawGuy = false;
public someGame(){
super("Some Game");
setSize(700,700);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addMouseListener(this);
addKeyListener(this);
}
public void paint(Graphics g){
super.paint(g);
g.setColor(Color.black);
for(int i = 0; i < lines.size(); i++){
Line2D.Double temp = (Line2D.Double) lines.get(i);
int x1 = Integer.parseInt(""+Math.round(temp.getX1()));
int x2 = Integer.parseInt(""+Math.round(temp.getX2()));
int y1 = Integer.parseInt(""+Math.round(temp.getY1()));
int y2 = Integer.parseInt(""+Math.round(temp.getY2()));
g.drawLine(x1,x2,y1,y2);
}
if(drawGuy){
try{
URL url = this.getClass().getResource("resources/img/world/char.png");
Image image = Toolkit.getDefaultToolkit().getImage(url);
g.drawImage(image, cow.x, cow.y, this);
} catch(Exception exc){}
}
}
public void mouseClicked(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseExited(MouseEvent e){}
public void mousePressed(MouseEvent e){
start = new Point2D.Double(e.getX(),e.getY());
}
public void mouseReleased(MouseEvent e){
Point2D.Double end = new Point2D.Double(e.getX(),e.getY());
lines.add(new Line2D.Double(start,end));
repaint();
}
public void keyPressed(KeyEvent e){}
public void keyReleased(KeyEvent e){}
public void keyTyped(KeyEvent e){
if(e.getKeyChar()=='p'||e.getKeyChar()=='P'){
thread = new Slider();
thread.start();
thread.action(true);
}
if(e.getKeyChar()=='q'||e.getKeyChar()=='Q'){
thread.action(false);
drawGuy = false;
thread = null;
}
}
private class Slider extends Thread{
double velocity, gravity;
boolean go = false;
public void run(){
if(go){
initGuy();
velocity = 0;
gravity = 1;
}
while(go){
try{
Line2D.Double lineTaken = null;
boolean onLine = false;
int firstOnLine = -1;
for(int i = lines.size()-1; i>=0; i--){
Line2D.Double temp = (Line2D.Double) lines.get(i);
if(temp.intersects(cow.x,cow.y,50,50)){
lineTaken = temp;
onLine = true;
if(firstOnLine!=i){
firstOnLine = i;
gravity = 0;
}
break;
}
}
if(onLine){
double grav = (lineTaken.y2-lineTaken.y1)/50;
double vlct = (lineTaken.x2-lineTaken.x1)/100;
if(velocity<5)velocity+=vlct;
if(gravity<2.5)gravity+=grav;
}
else{
gravity+=.2;
}
cow.x+=velocity;
cow.y+=gravity;
Thread.sleep(75);
repaint();
}catch(Exception e){break;}
}
}
public void action(boolean b){
go = b;
}
public void initGuy(){
Line2D.Double firstLine = (Line2D.Double) lines.get(0);
int x = Integer.parseInt(""+Math.round(firstLine.x1));
int y = Integer.parseInt(""+Math.round(firstLine.y1));
cow = new Rectangle(x+30,y-20,30,30);
drawGuy = true;
}
}
很抱歉输入大代码，但我不知道出了什么问题...
非常感谢任何回答的人:)
...是的，主要方法是someGame g = new someGame();
Sorry for the large code but I have no idea what went wrong...
Big thanks to anyone who answers :)
...and yes, the main method is someGame g = new someGame();
推荐答案
1)切勿在没有充分理由的情况下使用paint(..).而是扩展JPanel类并覆盖paintComponent(...).
1) You should never use paint(..) without a good reason. rather extend JPanel class and override paintComponent(...).
2)不要扩展JFrame类，除非添加功能
2) Dont extend JFrame class unless adding functionality
3)不要忘记应该在EDT上完成所有Swing组件的创建和操作-
3) Dont forget all Swing component creation and manipulation should be done on EDT - Event Dispatch Thread
4)Java命名约定为CamelCase，并且类名的每个新单词都应以大写字母开头，即SomeGame
4) Java naming convention is CamelCase, and each new word for a class name should begin with capitals i.e SomeGame
5)不要使用setSize而不是覆盖组件getPreferredSize并返回所需的大小，而不是在设置可见之前调用JFrame上的pack().
5) Dont use setSize rather override component getPreferredSize and return desired size and than call pack() on JFrame before setting visible.
6)使用 Keybindings 代替
6) Use Keybindings instead of KeyListener
7)使用 MouseAdapter 代替MouseListener
8)不要扩展Thread类而是实现Runnable 并创建start()方法以在可运行类中启动线程(我未在下面的代码中实现)
8) Do not extend Thread class rather implement Runnable and create start() method to start thread in runnable class (I have not implemented this in below code)
9)除了需要在paint方法中绘制对象外，不要执行长时间运行的任务(例如加载图像)或执行任何其他工作，这不是一个好主意，您应该在类初始化或至少在组件paint方法之外加载图片等. (我尚未在下面的代码中实现此功能)
9) Not a good idea to do long running tasks like load images or do any other work besides the necessaries for painting objects in paint method you should load picture etc on class initialization or at least outside of a components paint methods. (I have not implemented this in below code)
10)关于未正确绘制线条的最大问题是:
10) Your biggest problem about lines not being drawing correctly was:
g.drawLine(x1,x2,y1,y2);
Here is the code (Dont have time to explain right now hope you can understand):
我在@cadProgrammer在下面的评论中建议添加一些额外的内容，例如将内容投射到Graphics2D并使用RenderHints进行抗锯齿.
I added some extra stuff like casting to Graphics2D and using RenderHints for Anti-Aliasing as suggested by @MadProgrammer in his comment below.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.net.URL;
import java.util.ArrayList;
import javax.swing.AbstractAction;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
public class SomeGame {
public SomeGame() {
JFrame frame = new JFrame("Some Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DrawPanel dp = new DrawPanel();
frame.add(dp);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new SomeGame();
}
});
}
}
class DrawPanel extends JPanel {
ArrayList lines = new ArrayList();
Point2D.Double start;
final Color BROWN = new Color(156, 93, 82);
Slider thread;
Rectangle cow = null;
boolean drawGuy = false;
public DrawPanel() {
addMouseListener(new MouseAdapter() {
@Override
public void mouseReleased(MouseEvent me) {
super.mouseReleased(me);
Point2D.Double end = new Point2D.Double(me.getX(), me.getY());
lines.add(new Line2D.Double(start, end));
repaint();
}
@Override
public void mousePressed(MouseEvent me) {
super.mousePressed(me);
start = new Point2D.Double(me.getX(), me.getY());
}
});
setKeyBindings();
}
private void setKeyBindings() {
getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_P, 0), "P");
getActionMap().put("P", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent ae) {
thread = new Slider(DrawPanel.this);
thread.action(true);
thread.start();
}
});
getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_Q, 0), "q");
getActionMap().put("Q", new AbstractAction() {
@Override
public void actionPerformed(ActionEvent ae) {
thread.action(false);
drawGuy = false;
thread = null;
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(700, 700);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
//lets go 2D :)
Graphics2D g2d = (Graphics2D) g;
//turn on anti aliasing
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(Color.black);
for (int i = 0; i < lines.size(); i++) {
Line2D.Double temp = (Line2D.Double) lines.get(i);
int x1 = Integer.parseInt("" + Math.round(temp.getX1()));
int x2 = Integer.parseInt("" + Math.round(temp.getX2()));
int y1 = Integer.parseInt("" + Math.round(temp.getY1()));
int y2 = Integer.parseInt("" + Math.round(temp.getY2()));
g2d.drawLine(x1, y1, x2, y2);
}
if (drawGuy) {
try {
URL url = this.getClass().getResource("resources/img/world/char.png");
Image image = Toolkit.getDefaultToolkit().getImage(url);
g.drawImage(image, cow.x, cow.y, this);
} catch (Exception exc) {
}
}
}
private class Slider extends Thread {
double velocity, gravity;
boolean go = false;
private final DrawPanel dp;
private Slider(DrawPanel dp) {
this.dp = dp;
}
public void run() {
if (go) {
initGuy();
velocity = 0;
gravity = 1;
}
while (go) {
try {
Line2D.Double lineTaken = null;
boolean onLine = false;
int firstOnLine = -1;
for (int i = lines.size() - 1; i >= 0; i--) {
Line2D.Double temp = (Line2D.Double) lines.get(i);
if (temp.intersects(cow.x, cow.y, 50, 50)) {
lineTaken = temp;
onLine = true;
if (firstOnLine != i) {
firstOnLine = i;
gravity = 0;
}
break;
}
}
if (onLine) {
double grav = (lineTaken.y2 - lineTaken.y1) / 50;
double vlct = (lineTaken.x2 - lineTaken.x1) / 100;
if (velocity < 5) {
velocity += vlct;
}
if (gravity < 2.5) {
gravity += grav;
}
} else {
gravity += .2;
}
cow.x += velocity;
cow.y += gravity;
Thread.sleep(75);
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
dp.repaint();
}
});
} catch (Exception e) {
break;
}
}
}
public void action(boolean b) {
go = b;
}
public void initGuy() {
Line2D.Double firstLine = (Line2D.Double) lines.get(0);
int x = Integer.parseInt("" + Math.round(firstLine.x1));
int y = Integer.parseInt("" + Math.round(firstLine.y1));
cow = new Rectangle(x + 30, y - 20, 30, 30);
drawGuy = true;
}
}
}
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