Question

Here is the code which creates the bezier curve with total 4 control points:

Blue color is the starting and end control point.
Cyan color is the second and third control point.

I want to add a control point to the existing curve so that now I have 3 cyan coloured control points so that I can resize the curve(like dragging the curve) from any of these 3 control points instead of the 2 control points. What needs to be done for this?

I have attached the output of the below code as an attachment.

import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.GeneralPath;

public class Piyush extends Frame implements MouseListener, MouseMotionListener {

//  private int[] xs = { 75, 150, 300, 375 };
//
//  private int[] ys = { 250, 100, 350, 250 };

  private int[] xs = { 75, 200, 300, 375 };

  private int[] ys = { 250, 100, 100, 250 };

  private int dragIndex = NOT_DRAGGING;

  private final static int NEIGHBORHOOD = 15;

  private final static int NOT_DRAGGING = -1;

  public static void main(String[] args) {
    new Piyush();
  }

  public Piyush() {
    setSize(500, 450);
    addMouseListener(this);
    addMouseMotionListener(this);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    setVisible(true);
  }

  public void paint(Graphics g) {
    for (int i = 0; i < 4; i++) {
      if (i == 0 || i == 3){
        g.setColor(Color.blue);
      g.fillOval(xs[i] - 6, ys[i] - 6, 12, 12);}
      else{
        g.setColor(Color.cyan);
      g.fillOval(xs[i] - 6, ys[i] - 6, 12, 12);
        }

    }
    Graphics2D g2d = (Graphics2D) g;
    g2d.setColor(Color.black);
    GeneralPath path = new GeneralPath();
    path.moveTo(xs[0], ys[0]);
    path.curveTo(xs[1], ys[1], xs[2], ys[2], xs[3], ys[3]);
    g2d.draw(path);
  }

  public void mousePressed(MouseEvent e) {
    dragIndex = NOT_DRAGGING;
    int minDistance = Integer.MAX_VALUE;
    int indexOfClosestPoint = -1;
    for (int i = 0; i < 4; i++) {
      int deltaX = xs[i] - e.getX();
      int deltaY = ys[i] - e.getY();
      int distance = (int) (Math.sqrt(deltaX * deltaX + deltaY * deltaY));
      if (distance < minDistance) {
        minDistance = distance;
        indexOfClosestPoint = i;
      }
    }
    if (minDistance > NEIGHBORHOOD)
      return;

    dragIndex = indexOfClosestPoint;
  }

  public void mouseReleased(MouseEvent e) {
    if (dragIndex == NOT_DRAGGING)
      return;
    xs[dragIndex] = e.getX();
    ys[dragIndex] = e.getY();
    dragIndex = NOT_DRAGGING;
    repaint();
  }

  public void mouseDragged(MouseEvent e) {
    if (dragIndex == NOT_DRAGGING)
      return;

    xs[dragIndex] = e.getX();
    ys[dragIndex] = e.getY();
    repaint();
  }

  public void mouseClicked(MouseEvent e) {
  }

  public void mouseEntered(MouseEvent e) {
  }

  public void mouseExited(MouseEvent e) {
  }

  public void mouseMoved(MouseEvent e) {
  }
}

Answer 1

也在这里问到

http://www.dreamincode.net/forums/topic/408270-need-help-in-adding-a-control-point-for-bezier-curve/page__pid__2347742__st__0&#entry2347742

代码库来自这里

http://www.java2s.com/Tutorials/Java/Graphics/Shape/Drag_the_control_point_for_Bezier_curve_in_Java.htm

How to add an extra control point to a Bezier curve?

1 个答案: