我一直在与 Path2D.Double 合作现在大约一天左右，in this post 我请求有关设置控制点以允许路径通过指定点的帮助。我将一些代码混合在一起作为快速测试床，随机生成点，然后根据上面帖子中提到的信息将路径弯曲到这些点。
这是可运行的代码，抱歉它是整体的，我希望它是可发布的，以便您可以跟随:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JFrame;
public class Curver {
public static ArrayList<Point2D> points = new ArrayList<Point2D>();
/**
* @param args
*/
public static void main(String[] args) {
final JFrame window = new JFrame();
window.setPreferredSize(new Dimension(500,500));
window.setLocationRelativeTo(null);
window.addMouseListener(new MouseListener() {
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseClicked(MouseEvent e) {
new Thread(new Runnable(){
@Override
public void run() {
Random random = new Random();
while(true){
points.add(new Point2D.Double(random.nextInt(window.getWidth()-1)+1,random.nextInt(window.getHeight()-1)+1));
System.out.println(points.size());
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}).start();
}
});
window.pack();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
int div = 7;
int d = 4;
Path2D.Double path = new Path2D.Double();
Point2D currentPoint;
double startX, startY;
double interiorX_In, interiorY_In;
double interiorX_Out, interiorY_Out;
double endX, endY;
Graphics2D g;
while(true){
g = (Graphics2D) window.getGraphics();
g.setColor(Color.blue);
for(int i = 0; i < points.size(); i++){
currentPoint = points.get(i);
g.fillRect((int)currentPoint.getX(), (int)currentPoint.getY(), d, d);
if (i == 0){
// Don't attempt any line drawing as we don't have enough points.
path.moveTo(currentPoint.getX(), currentPoint.getY());
} else if (i == 1 && points.size() > 2){
// draw first curve with knowledge of third point (third point is not end point)
startX = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-1).getX()) / div; // from start
startY = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-1).getY()) / div;
interiorX_In = currentPoint.getX() - (points.get(i+1).getX() - points.get(i-1).getX()) / div; // to interior
interiorY_In = currentPoint.getY() - (points.get(i+1).getY() - points.get(i-1).getY()) / div;
path.curveTo(startX, startY, interiorX_In, interiorY_In, currentPoint.getX(), currentPoint.getY());
} else if (i == 1){ // Only 2 points in list so use a straight line until more points are available.
g.drawLine((int) points.get(i-1).getX(), (int) points.get(i-1).getY(), (int)currentPoint.getX(), (int)currentPoint.getY());
} else if (i >= 1 && i < points.size()-1){ // interior to interior edge.
interiorX_Out = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-2).getX()) / div; // from interior
interiorY_Out = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-2).getY()) / div;
interiorX_In = currentPoint.getX() - (points.get(i+1).getX() - points.get(i-1).getX()) / div; // to interior
interiorY_In = currentPoint.getY() - (points.get(i+1).getY() - points.get(i-1).getY()) / div;
path.curveTo(interiorX_Out, interiorY_Out, interiorX_In, interiorY_In, currentPoint.getX(), currentPoint.getY());
} else { // from interior point to end point.
interiorX_Out = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-2).getX()) / div; // from interior
interiorY_Out = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-2).getY()) / div;
endX = currentPoint.getX() - (currentPoint.getX() - points.get(i-1).getX()) / div; // to end
endY = currentPoint.getY() - (currentPoint.getY() - points.get(i-1).getY()) / div;
path.curveTo(interiorX_Out, interiorY_Out, endX, endY, currentPoint.getX(), currentPoint.getY());
}
} // end for
g.clearRect(0, 0, window.getWidth(), window.getHeight());
g.draw(path);
path.reset();
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
- 只需单击 JFrame 即可开始绘制随机点 - 控制台将报告正在绘制的点的数量。
我遇到的问题是，一旦我向上或 60-65 个随机点，路径就会闪烁，并且似乎在屏幕上缩小，并且通常表现出奇怪的行为？ 正如我所说，代码可能并不完美，所以任何人都可以给我一些关于如何减少错误的指示。
我认为奇怪的行为来自于每次重新绘制 JFrame 时构造越来越长的路径？也许有一种方法可以将路径绘制为连续的线，因为我认为路径被解释为一系列线段？或者也许使路径累积而不是为运行循环的每次迭代重建整个路径？
期待提供任何建议 - 但请尝试解释一下，因为我对绘画和路径等相对较新。
提前致谢。
感谢@camickr 的帖子。 这是重新编写的代码，可以完美运行，有 3,500 多个随机点，没有一个小故障:
> import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Path2D;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Curver extends JFrame implements ActionListener, MouseListener{
public Timer animationTicker = new Timer(50, this);
public ArrayList<Point2D> points = new ArrayList<Point2D>();
private Canvas canvas;
public Curver(){
this.setPreferredSize(new Dimension(500,500));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setLayout(new BorderLayout());
canvas = new Canvas(points);
this.add(canvas, BorderLayout.CENTER);
this.addMouseListener(this);
this.pack();
this.setVisible(true);
}
class Canvas extends JPanel{
int div = 7;
int d = 4;
Path2D.Double path = new Path2D.Double();
Point2D currentPoint;
double startX, startY;
double interiorX_In, interiorY_In;
double interiorX_Out, interiorY_Out;
double endX, endY;
Graphics2D g2;
ArrayList<Point2D> points;
public Canvas(ArrayList<Point2D> points){
this.setMinimumSize(new Dimension(100,100));
this.points = points;
}
@Override
public void paintComponent(Graphics g) {
g2 = (Graphics2D) g;
g.setColor(Color.blue);
synchronized(points){
for(int i = 0; i < points.size(); i++){
currentPoint = points.get(i);
g2.fillRect((int)currentPoint.getX(), (int)currentPoint.getY(), d, d);
if (i == 0){
// Don't attempt any line drawing as we don't have enough points.
path.moveTo(currentPoint.getX(), currentPoint.getY());
} else if (i == 1 && points.size() > 2){
// draw first curve with knowledge of third point (third point is not end point)
startX = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-1).getX()) / div; // from start
startY = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-1).getY()) / div;
interiorX_In = currentPoint.getX() - (points.get(i+1).getX() - points.get(i-1).getX()) / div; // to interior
interiorY_In = currentPoint.getY() - (points.get(i+1).getY() - points.get(i-1).getY()) / div;
path.curveTo(startX, startY, interiorX_In, interiorY_In, currentPoint.getX(), currentPoint.getY());
} else if (i == 1){ // Only 2 points in list so use a straight line until more points are available.
g2.drawLine((int) points.get(i-1).getX(), (int) points.get(i-1).getY(), (int)currentPoint.getX(), (int)currentPoint.getY());
} else if (i >= 1 && i < points.size()-1){ // interior to interior edge.
interiorX_Out = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-2).getX()) / div; // from interior
interiorY_Out = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-2).getY()) / div;
interiorX_In = currentPoint.getX() - (points.get(i+1).getX() - points.get(i-1).getX()) / div; // to interior
interiorY_In = currentPoint.getY() - (points.get(i+1).getY() - points.get(i-1).getY()) / div;
path.curveTo(interiorX_Out, interiorY_Out, interiorX_In, interiorY_In, currentPoint.getX(), currentPoint.getY());
} else { // from interior point to end point.
interiorX_Out = points.get(i-1).getX() + (currentPoint.getX() - points.get(i-2).getX()) / div; // from interior
interiorY_Out = points.get(i-1).getY() + (currentPoint.getY() - points.get(i-2).getY()) / div;
endX = currentPoint.getX() - (currentPoint.getX() - points.get(i-1).getX()) / div; // to end
endY = currentPoint.getY() - (currentPoint.getY() - points.get(i-1).getY()) / div;
path.curveTo(interiorX_Out, interiorY_Out, endX, endY, currentPoint.getX(), currentPoint.getY());
}
} // end for
g.clearRect(0, 0, this.getWidth(), this.getHeight());
g2.draw(path);
path.reset();
}
}
} // end of inner class
@Override
public void actionPerformed(ActionEvent e) {
this.canvas.repaint();
}
@Override
public void mouseClicked(MouseEvent e) {
new Thread(new Runnable(){
@Override
public void run() {
System.out.println("Thread running");
Random random = new Random();
while(true){
synchronized(points){
points.add(new Point2D.Double(random.nextInt(getWidth()-1)+1,random.nextInt(getHeight()-1)+1));
System.out.println(points.size());
}
try {
Thread.sleep(60);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
}
@Override
public void mousePressed(MouseEvent e) {}
@Override
public void mouseReleased(MouseEvent e) {}
@Override
public void mouseEntered(MouseEvent e) {}
@Override
public void mouseExited(MouseEvent e) {}
public static void main(String[] args) {
Curver curver = new Curver();
curver.animationTicker.start();
}
}
最佳答案
g = (Graphics2D) window.getGraphics();
我没有仔细查看您的代码，但论坛建议不要使用 getGraphics() 方法进行绘画。
自定义绘制是通过重写 JPanel(或 JComponent)的 PaintComponent() 方法来完成的。然后将面板添加到框架中。阅读 Swing 教程以获取有关自定义绘画的更多信息。
另外，不要使用“while (true)”逻辑。 Swing 将根据需要重新绘制。如果您想要某种动画，请使用 Swing Timer。
关于java - Path2D 绘制错误？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15884223/