我试图让一个球在您按下其中一个箭头键时逐渐移动，现在它有点像瞬移。我想要它，这样你就可以看到它在移动。基于此example ，我正在使用键绑定(bind)，并且有一个名为 delta 的变量会导致球移动 50 像素，但就像我说的那样，无论你按下箭头键的哪个方向，球都会出现 50 像素，我希望它就像你要踢一个球，你可以看到它从 a 点到 b 点。转到我认为问题所在的第 89 行。
package game;
import java.awt.BasicStroke;
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.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
/**
* @see https://stackoverflow.com/questions/6991648
* @see https://stackoverflow.com/questions/6887296
* @see https://stackoverflow.com/questions/5797965
*/
public class LinePanel extends JPanel {
myObject ball;
private Point b1 = new Point(0,0);
private MouseHandler mouseHandler = new MouseHandler();
private Point p1 = new Point(100, 100);
private Point p2 = new Point(540, 380);
private boolean drawing;
public LinePanel() {
this.setPreferredSize(new Dimension(640, 480));
this.addMouseListener(mouseHandler);
this.addMouseMotionListener(mouseHandler);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.blue);
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(8,
BasicStroke.CAP_ROUND, BasicStroke.JOIN_BEVEL));
g.drawLine(p1.x, p1.y, p2.x, p2.y);
ball = new myObject(b1.x,b1.y,"Stuff/ball.png",50,50);
g.drawImage(ball.getImage(),ball.getX(),ball.getY(), ball.getWidth(), ball.getHeight(), null);
repaint();
}
private class MouseHandler extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
drawing = true;
p1 = e.getPoint();
p2 = p1;
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
drawing = false;
p2 = e.getPoint();
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
if (drawing) {
p2 = e.getPoint();
repaint();
}
}
}
private class ControlPanel extends JPanel {
private static final int DELTA = 50;
// above is telling the ball to move by 50 pixels
// I want it to move by 50 pixels but gradually I dont want it to teleport
public ControlPanel() {
this.add(new MoveButton("\u2190", KeyEvent.VK_LEFT, -DELTA, 0));
this.add(new MoveButton("\u2191", KeyEvent.VK_UP, 0, -DELTA));
this.add(new MoveButton("\u2192", KeyEvent.VK_RIGHT, DELTA, 0));
this.add(new MoveButton("\u2193", KeyEvent.VK_DOWN, 0, DELTA));
}
private class MoveButton extends JButton {
KeyStroke k;
int myX, myY;
public MoveButton(String name, int code, final int myX, final int myY) {
super(name);
this.k = KeyStroke.getKeyStroke(code, 0);
this.myX = myX;
this.myY = myY;
this.setAction(new AbstractAction(this.getText()) {
@Override
public void actionPerformed(ActionEvent e) {
LinePanel.this.b1.translate(myX, myY);
LinePanel.this.repaint();
}
});
ControlPanel.this.getInputMap(
WHEN_IN_FOCUSED_WINDOW).put(k, k.toString());
ControlPanel.this.getActionMap().put(k.toString(), new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
MoveButton.this.doClick();
}
});
}
}
}
private void display() {
JFrame f = new JFrame("LinePanel");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.add(new ControlPanel(), BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new LinePanel().display();
}
});
}
}
最佳答案
任何动画的基本前提是随时间变化。
您需要能够在给定时间段内将球从位置 A 移动到位置 B。为此，您需要某种可用于更新该时间段内球位置的“自动收报机”。一般来说，25fps(或大约 40 毫秒)绰绰有余。
要在 Swing 中安全地实现这一点，最简单的解决方案是使用 Swing Timer。您可以使用 Thread，但随后您需要负责将更新同步回 UI，并且在这个阶段确实需要更复杂。
此示例使用 1 秒的持续时间将球从 A 点移动到 B 点。这是一个线性动画，您需要研究适当的动画框架以获得更复杂的解决方案。
import java.awt.BasicStroke;
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.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
public class LinePanel extends JPanel {
// myObject ball;
private Point b1 = new Point(0, 0);
private Point startPoint = new Point(0, 0);
private Point targetPoint = new Point(0, 0);
private MouseHandler mouseHandler = new MouseHandler();
private Point p1 = new Point(100, 100);
private Point p2 = new Point(540, 380);
private boolean drawing;
private Timer animate;
private long startTime;
private int duration = 1000;
public LinePanel() {
this.setPreferredSize(new Dimension(640, 480));
this.addMouseListener(mouseHandler);
this.addMouseMotionListener(mouseHandler);
animate = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
long now = System.currentTimeMillis();
long dif = now - startTime;
if (dif >= duration) {
dif = duration;
((Timer)e.getSource()).stop();
}
float progress = (float)dif / (float)duration;
b1 = calculateProgress(startPoint, targetPoint, progress);
repaint();
}
});
animate.setRepeats(true);
animate.setCoalesce(true);
}
public void moveBallTo(Point target) {
if (animate.isRunning()) {
animate.stop();
}
startPoint = b1;
targetPoint = target;
startTime = System.currentTimeMillis();
animate.start();
}
public void moveBallBy(int xDelta, int yDelta) {
animate.stop();
Point t = new Point(targetPoint == null ? b1 : targetPoint);
t.x += xDelta;
t.y += yDelta;
moveBallTo(t);
}
public Point calculateProgress(Point startPoint, Point targetPoint, double progress) {
Point point = new Point();
if (startPoint != null && targetPoint != null) {
point.x = calculateProgress(startPoint.x, targetPoint.x, progress);
point.y = calculateProgress(startPoint.y, targetPoint.y, progress);
}
return point;
}
public int calculateProgress(int startValue, int endValue, double fraction) {
int value = 0;
int distance = endValue - startValue;
value = (int)Math.round((double)distance * fraction);
value += startValue;
return value;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.blue);
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(8,
BasicStroke.CAP_ROUND, BasicStroke.JOIN_BEVEL));
g.drawLine(p1.x, p1.y, p2.x, p2.y);
g.setColor(Color.RED);
g.drawOval(b1.x - 4, b1.y - 4, 8, 8);
// ball = new myObject(b1.x, b1.y, "Stuff/ball.png", 50, 50);
// g.drawImage(ball.getImage(), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight(), null);
repaint();
}
private class MouseHandler extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
drawing = true;
p1 = e.getPoint();
p2 = p1;
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
drawing = false;
p2 = e.getPoint();
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
if (drawing) {
p2 = e.getPoint();
repaint();
}
}
}
private class ControlPanel extends JPanel {
private static final int DELTA = 50;
// above is telling the ball to move by 50 pixels
// I want it to move by 50 pixels but gradually I dont want it to teleport
public ControlPanel() {
this.add(new MoveButton("\u2190", KeyEvent.VK_LEFT, -DELTA, 0));
this.add(new MoveButton("\u2191", KeyEvent.VK_UP, 0, -DELTA));
this.add(new MoveButton("\u2192", KeyEvent.VK_RIGHT, DELTA, 0));
this.add(new MoveButton("\u2193", KeyEvent.VK_DOWN, 0, DELTA));
}
private class MoveButton extends JButton {
KeyStroke k;
int myX, myY;
public MoveButton(String name, int code, final int myX, final int myY) {
super(name);
this.k = KeyStroke.getKeyStroke(code, 0);
this.myX = myX;
this.myY = myY;
this.setAction(new AbstractAction(this.getText()) {
@Override
public void actionPerformed(ActionEvent e) {
// LinePanel.this.b1.translate(myX, myY);
moveBallBy(myX, myY);
LinePanel.this.repaint();
}
});
ControlPanel.this.getInputMap(
WHEN_IN_FOCUSED_WINDOW).put(k, k.toString());
ControlPanel.this.getActionMap().put(k.toString(), new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
MoveButton.this.doClick();
}
});
}
}
}
private void display() {
JFrame f = new JFrame("LinePanel");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.add(new ControlPanel(), BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new LinePanel().display();
}
});
}
}
看看...
旁注
在您的 paint 方法中执行此 ball = new myObject(b1.x, b1.y, "Stuff/ball.png", 50, 50); 效率极低。 paint 可以快速连续调用多次。在任何可能的情况下，您都希望尽可能优化 paint 方法，在 paint 方法上花费太多时间会使您的程序看起来很慢
关于java - 我试图让球逐渐移动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15078835/