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java - 我已经重写了paintComponent(),那么为什么我的形状没有出现呢?

转载 作者:行者123 更新时间:2023-12-02 00:27:56 26 4
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我正在摆弄 awt 图形,一开始我设法得到了我想要的一切,但是在清理我的代码之后,突然除了一个空框架之外什么都没有出现,其中包含 JPanel。

这可能是非常明显的,但我找不到为什么我的形状不再出现。我做错了什么?

public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Game().setVisible(true);
}
});
}
}
public class Game extends JFrame {
static int width = 500;
static int height = 500;

public Game() {
this.setPreferredSize(new Dimension(width, height));
JPanel menuPanel = new JPanel(); // Menypanel
JPanel filmPanel = new JPanel(); // Filmpanel
JPanel gamePanel = new JPanel(); // Spelpanel
gamePanel.setBackground(Color.WHITE);

// Intro texts
Queue<String> intro = new ArrayDeque<>();
intro.add("Welcome to the jungle!");
intro.add("We've got fun and games.");
FadingTextBox introBox = new FadingTextBox(intro);
gamePanel.add(introBox);

getContentPane().add(gamePanel);
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
pack();
}
}

这个根本没有出现:

class FadingTextBox extends JComponent implements ActionListener {
private RoundRectangle2D rr;
private String text = "";
private float alpha;
private float alphaDelta = 0.05f; // Alpha fade speed
private final int fps = 60; // FPS
private javax.swing.Timer timer = new Timer(1000 / fps, this);
private java.util.Queue<String> textQueue; // Contains lines of texts

public FadingTextBox(java.util.Queue<String> textQueue) {
this.textQueue = textQueue;
this.setFont(new Font("OCR A EXTENDED", Font.BOLD, 24));

int arc = 10;
int height = (int) (Game.height * 0.2);
int width = (int) (Game.width - Game.width * 0.1);
int x = Game.width / 2 - width / 2;
int y = (int) (Game.height - height * 1.5);

rr = new RoundRectangle2D.Double(x, y, width, height, arc, arc);

setText(textQueue.remove());
timer.start();
}

private void setText(String text) {
this.text = text;
}

boolean isRunning() {
return timer.isRunning();
}

@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;

// Set component alpha
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));

// Draw RoundRectangle
g2.setBackground(Color.DARK_GRAY);
g2.fill(rr);

// Draw text
// g2.setColor(Color.BLUE);
final FontMetrics fm = g.getFontMetrics();
Rectangle2D textBounds = fm.getStringBounds(text, g2);
g2.drawString(text, (float) (rr.getCenterX() - (textBounds.getWidth() / 2)), (float) (rr.getCenterY() + textBounds.getHeight() / 2));
}

@Override
public void actionPerformed(ActionEvent e) {
if (alpha >= 0) {
alpha += alphaDelta;
}
if (alpha < 0) {
alpha = 0;
try {
setText(textQueue.remove());
} catch (NoSuchElementException ex) {
timer.stop();
}
alphaDelta *= -1;
} else if (alpha >= 1) {
alpha = 1;
alphaDelta *= -1;

// Sleep 1 sec on full alpha
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
repaint();
}
}

新观点:

public class Game extends JFrame {
...
GameCanvas gameCanvas;

public Game() {
...
gameCanvas = new GameCanvas(); // Spelpanel
getContentPane().add(gameCanvas);
...
pack();
}
}
import javax.swing.*;
import java.awt.*;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.util.ArrayDeque;
import java.util.NoSuchElementException;

public class GameCanvas extends Canvas implements Runnable {
private final int fps = 24; // FPS
private RoundRectangle2D rr;
private String text;
private float alpha;
private float alphaDelta = 0.05f; // Alpha fade speed
private javax.swing.Timer timer = new Timer(1000 / fps, a -> repaint());
private java.util.Queue<String> textQueue; // Contains lines of texts

public GameCanvas() {
this.setFont(new Font("OCR A EXTENDED", Font.BOLD, 20));
// Intro texts
textQueue = new ArrayDeque<>();
textQueue.add("Welcome to the jungle!");
textQueue.add("We've got fun and games.");

// RoundRectangle
int arc = 10;
int height = (int) (Game.height * 0.2);
int width = (int) (Game.width - Game.width * 0.1);// (int) (Game.width - Game.width * 0.5);
int x = Game.width / 2 - width / 2 - 10;
int y = (int) (Game.height - height * 1.5);
rr = new RoundRectangle2D.Double(x, y, width, height, arc, arc);

this.text = textQueue.remove();
Thread thread = new Thread(this); // Fade thread
thread.start();
timer.start();

}

@Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D) g;

// Set component alpha

// g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));

// Draw RoundRectangle
g2.setBackground(Color.DARK_GRAY);
g2.fill(rr);

// Draw text
final FontMetrics fm = g2.getFontMetrics();
Rectangle2D textBounds = fm.getStringBounds(text, g2);
g2.setColor(Color.WHITE);
g2.drawString(text, (float) (rr.getCenterX() - (textBounds.getWidth() / 2)), (float) (rr.getCenterY() + textBounds.getHeight() / 2));
g2.setColor(Color.DARK_GRAY);
}

@Override
public void run() {
while (true) {
if (alpha >= 0) {
alpha += alphaDelta;
}
if (alpha < 0) {
alpha = 0;
try {
this.text = textQueue.remove();
} catch (NoSuchElementException ex) {
timer.stop();
}
alphaDelta *= -1;
} else if (alpha >= 1) {
alpha = 1;
alphaDelta *= -1;

// Sleep 1 sec on full alpha
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}

最佳答案

因为你gamePanel没有 LayoutManager (默认情况下它使用 FlowLayout)用组件填充面板。为了查看某些内容,请将其更改为 JPanel gamePanel = new JPanel(new BorderLayout());

但是,在 Timer你的行动Thread.sleep() 。这将卡住整个 GUI,因为 Timer的 Action 监听器在事件调度线程中运行,这是一个 Thread那不应该sleep 。相反,您可以使用第二个 Timer或某种标志变量,或者可能是 SwingWorker .

关于java - 我已经重写了paintComponent(),那么为什么我的形状没有出现呢?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58039397/

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