组合圆弧和矩形时出现小间隙 [英] Small gaps appear when combining arcs and rectangles

问题描述

我正在尝试通过一系列小的角弧和矩形来模拟一个角.

I'm trying simulate a corner by a series of small angular arcs and rectangles.

当它在开启抗锯齿的情况下渲染时，我得到如下图:

When it renders with anti-aliasing turned on, I get a picture like below:

http://i.imgur.com/xgzme.png

当我关闭抗锯齿时，我得到以下图片:

When I turn anti-aliasing off, I get the following picture:

http://i.imgur.com/mB6Id.png

看起来好像我的计算差了一两个像素，但我在所有渲染中都使用了双精度，所以我什至不认为是这种情况.

It almost looks as if my computations are off by a pixel or two, but I'm using doubles for all of the rendering, so I don't even think that is the case.

类的代码在这里:

http://pastebin.com/1SHu7rH0

这不是什么大问题，因为线条几乎不会分散注意力或计算的严重错误，但如果可能的话，我希望能够修复它.

It's not a huge issue with it, as the lines are hardly a distraction or serious error of calculation, but it is something that I would like to be able to fix, if at all possible.

谢谢

推荐答案

实际上问题可能出在只使用 fill(Shape):它只填充内部.也可以调用 draw(Shape) 来修复形状不对齐的问题.

actually the problem might be using only fill(Shape): it only fills the interior. Calling draw(Shape) as well might fix the Shapes not lining up.

你为什么不把弯道画成一个单一的形状?

Why aren't you painting the bends as a single shape?

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.geom.Arc2D;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Path2D;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class TestDonut extends JPanel {
    public TestDonut() {
        setPreferredSize(new Dimension(100, 100));
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        Ellipse2D.Double gap = new Ellipse2D.Double(25, 25, 50, 50);
        Ellipse2D.Double circle = new Ellipse2D.Double(0, 0, 100, 100);
        Shape quarter = new Rectangle(50, 50, 50, 50);
        Area donut = new Area(circle);
        donut.subtract(new Area(gap));
        Area quarterDonut = new Area(quarter);
        quarterDonut.subtract(donut);

        Area bend = new Area(quarter);
        bend.subtract(quarterDonut);
        g.setColor(Color.RED);
        ((Graphics2D) g).fill(bend);

        Path2D.Double bend2 = new Path2D.Double();
        bend2.moveTo(0, 50);
        bend2.quadTo(0, 0, 50, 0);
        bend2.lineTo(50, 25);
        bend2.quadTo(25, 25, 25, 50);
        bend2.closePath();
        g.setColor(Color.GREEN);
        ((Graphics2D) g).fill(bend2);

        Arc2D.Double outerArc = new Arc2D.Double(0, 0, 100, 100, 0, 90, Arc2D.PIE);
        Arc2D.Double innerArc = new Arc2D.Double(25, 25, 50, 50, 0, 90, Arc2D.PIE);
        Area bend3 = new Area(outerArc);
        bend3.subtract(new Area(innerArc));
        g.setColor(Color.BLUE);
        ((Graphics2D) g).fill(bend3);

    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                frame.getContentPane().add(new TestDonut());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}

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