如何绘制更平滑的路径

Question

我有一个程序允许用户 select 一个大小并绘制一条自由曲线，类似于图形程序的笔功能。为此，我正在使用 Path2D。

我正在寻找一种减少绘制路径锯齿的方法。最初我为这个功能使用了path.lineTo，导致左边的锯齿状路径。然后我尝试了 path.curveTo，但是这在路径上产生了各种尖锐的区域，如右图所示。

有没有办法用 Path2D 使曲线平滑？

import ...

public class Test extends JPanel implements MouseListener, MouseMotionListener {
    int count, midX, midY, curveX, curveY;
    Point startPoint, stopPoint, releasePoint;
    Shape pathShape;

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g.create();
        if (pathShape != null) {
            g2.setStroke(new BasicStroke(50));
            g2.draw(pathShape);
        }
    }

    @Override
    public void mousePressed(MouseEvent ev) {
        count = 1;
        startPoint = new Point(ev.getPoint());
        Path2D.Double path = new Path2D.Double();
        pathShape = path;
        repaint();
    }

    @Override
    public void mouseReleased(MouseEvent ev) {
        releasePoint = new Point(ev.getPoint());
        Path2D path = (Path2D) pathShape;
        path.moveTo(releasePoint.x,releasePoint.y);
        path.closePath();
        pathShape = path;
    }

    // The mouseDragged method where lineTo is used.
    @Override
    public void mouseDragged(MouseEvent ev) {
        stopPoint = ev.getPoint();
        Path2D path = (Path2D) pathShape;
        path.moveTo(startPoint.x,startPoint.y);
        path.lineTo(stopPoint.x,stopPoint.y);
        pathShape = path;
        startPoint = stopPoint;
        repaint();
    }

    // The mouseDragged method where curveTo is used.
    @Override
    public void mouseDragged(MouseEvent ev) {
        if (count == 2) {
            midX = stopPoint.x;
            midY = stopPoint.y;
        }
        if (count++ >= 3) {
            curveX = midX;
            curveY = midY;
            midX = stopPoint.x;
            midY = stopPoint.y;
        }
        stopPoint = ev.getPoint();
        Path2D path = (Path2D) pathShape;
        path.moveTo(startPoint.x,startPoint.y);
        if (count >= 3)
            path.curveTo(curveX,curveY,midX,midY,stopPoint.x,stopPoint.y);
        else
            path.lineTo(stopPoint.x,stopPoint.y);
        pathShape = path;
        startPoint = stopPoint;
        repaint();
    }
}

Answer 1

尝试使用

g2.setStroke(new BasicStroke(50, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));

而不是g2.setStroke(new BasicStroke(50));

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