正如在对您之前的类似问题的评论中提到的:
- 不要在您的paintComponent 方法中绘制离散的椭圆。
- 而是通过在相邻点之间绘制线条来连接 PaintComponent 中列表中的点。
- 如果您需要使线条更粗,请更改 Graphics2D 对象的 Stroke 属性,使用更粗的线。
- 但是要小心 Strokes,因为您通常不希望属性更改沿着绘制链传播。这意味着有时您会想要复制 Graphics 对象并在新的 Graphics 对象上设置 Stroke 并使用它进行绘制,然后将其丢弃。
- 创建 Stroke 的最简单方法是使用 BasicStroke 类,例如,
new BasicStroke(6f)
它会为您提供一条漂亮的粗曲线。
例如:
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class Painter2 extends JPanel {
private static final float STROKE_WIDTH = 15f;
private static final Stroke STROKE = new BasicStroke(STROKE_WIDTH, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
int x, y;
ArrayList<Point> points;
public Painter2() {
setBackground(Color.white);
points = new ArrayList<>();
MouseHandler listener = new MouseHandler();
this.addMouseMotionListener(listener);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
private class MouseHandler extends MouseAdapter implements MouseMotionListener {
@Override
public void mouseDragged(MouseEvent e) {
Point point = new Point(e.getX(), e.getY());
points.add(point);
repaint();
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setStroke(STROKE);
for (int i = 1; i < points.size(); i++) {
int x1 = points.get(i - 1).x;
int y1 = points.get(i - 1).y;
int x2 = points.get(i).x;
int y2 = points.get(i).y;
g2d.drawLine(x1, y1, x2, y2);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame f = new JFrame();
f.setContentPane(new Painter2());
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}
或者更好:
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
@SuppressWarnings("serial")
public class Painter2 extends JPanel {
private static final float STROKE_WIDTH = 15f;
private static final Stroke STROKE = new BasicStroke(STROKE_WIDTH, BasicStroke.CAP_ROUND,
BasicStroke.JOIN_ROUND);
private static final Color CURVES_COLOR = Color.BLUE;
private static final Color TEMP_CURVE_COLOR = Color.PINK;
private List<List<Point>> curvesList = new ArrayList<>();
private List<Point> tempCurve = null;
public Painter2() {
setBackground(Color.white);
MouseHandler listener = new MouseHandler();
addMouseListener(listener);
addMouseMotionListener(listener);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
private class MouseHandler extends MouseAdapter implements MouseMotionListener {
@Override
public void mousePressed(MouseEvent e) {
tempCurve = new ArrayList<>();
tempCurve.add(e.getPoint());
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
tempCurve.add(e.getPoint());
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
tempCurve.add(e.getPoint());
curvesList.add(tempCurve);
tempCurve = null;
repaint();
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g.create();
g2.setStroke(STROKE);
g2.setColor(CURVES_COLOR);
for (List<Point> curve : curvesList) {
drawCurve(g2, curve);
}
if (tempCurve != null) {
g2.setColor(TEMP_CURVE_COLOR);
drawCurve(g2, tempCurve);
}
g2.dispose();
}
private void drawCurve(Graphics2D g2, List<Point> ptList) {
for (int i = 1; i < ptList.size(); i++) {
int x1 = ptList.get(i - 1).x;
int y1 = ptList.get(i - 1).y;
int x2 = ptList.get(i).x;
int y2 = ptList.get(i).y;
g2.drawLine(x1, y1, x2, y2);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame f = new JFrame();
f.setContentPane(new Painter2());
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
});
}
}