我正在尝试制作一个程序,在JFrame
的中心绘制一个圆圈并使用paintComponent
绘制圆圈。我的目标是即使JFrame
调整大小,也让圆圈在框架中居中。我试过并寻找不同的东西但没有任何效果。我猜我必须使用repaint()
和计时器但不知道具体如何。我的代码如下:
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ImageFrame extends JFrame {
private static final long serialVersionUID = 1L;
int width = 40;
int height = 40;
int x;
int y;
JPanel panel = new JPanel() {
private static final long serialVersionUID = 2L;
public void paintComponent(Graphics g) {
super.paintComponents(g);
g.drawOval(x, y, width, height);
}
};
public ImageFrame() {
add(panel);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(400, 300);
x = (getWidth()/2) - (width/2)-20;
y = (getHeight()/2) - (height/2)-40;
setLocationRelativeTo(null);
setVisible(true);
}
}
更新
我添加了TrashGod的方法,但是它说要删除@Override
,然后如果运行,JFrame
会打开,但没有圆圈。代码如下,我已经从旧代码中删除了paintComponent
。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ImageFrame extends JFrame implements {
private static final long serialVersionUID = 1L;
public ImageFrame() {
addMouseListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(400, 300);
setLocationRelativeTo(null);
setVisible(true);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
Dimension size = this.getSize();
int d = 200;
int x = (size.width - d) / 2;
int y = (size.height - d) / 2;
g.fillOval(x, y, d, d);
g.setColor(Color.blue);
g.drawOval(x, y, d, d);
}
}
答案 0 :(得分:2)
此example使圆圈居中并将尺寸调整为较小的尺寸,但您可以使d
保持不变。关键步骤是相对于面板的当前大小进行渲染。调整封闭框架的大小以查看效果。添加RenderingHints
,看到here,会使图形变得窒息。
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
Dimension size = this.getSize();
int d = 200;
int x = (size.width - d) / 2;
int y = (size.height - d) / 2;
g.fillOval(x, y, d, d);
g.setColor(Color.blue);
g.drawOval(x, y, d, d);
}
example的更改:
$ diff OldSwingPaint.java SwingPaint.java
38a39,41
> Graphics2D g2d = (Graphics2D) g;
> g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
> RenderingHints.VALUE_ANTIALIAS_ON);
40c43
< int d = Math.min(size.width, size.height) - 10;
---
> int d = 200;