Java如何用Graphics2D制作抗锯齿线？

Question

我试图用Graphics2D做一个画板，我在MouseMotionlistener方法mouseDragged中从两个点(一个startPoint和一个endPoint )画一条线，但是每当我添加这条线时，它看起来确实参差不齐和粗糙。我用它来帮助AntiAliasing，但它似乎什么也做不了。

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

但它对高冲程没有任何帮助。这是我的绘图代码。

public void mouseDragged(MouseEvent e) {
        //sets up graphics2d object
        g2 = (Graphics2D)getGraphics();
        g2.setStroke(new BasicStroke(strokeSize));
        g2.setColor(color);
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        //draws line using points and shapes
        endPoint = e.getPoint();
        Shape line = new Line2D.Double(beginPoint, endPoint);
        g2.draw(line);
        beginPoint = endPoint;

在mousePressed中为beginPoint赋值

Answer 1

有很多(非常酷的)渲染提示！我建议你开始尝试所有的组合，看看什么组合能给你带来想要的结果！

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import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            // Remember, graphics is a shared context, when you make changes
            // to it, you should also undo them.  To this end, we use create/dispose
            // which takes a snapshot of the current state and restores it at the
            // end.
            Graphics2D g2 = (Graphics2D) g.create();
            g2.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
            g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
            g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);

            g2.setColor(Color.BLACK);
            g2.drawLine(0, 0, getWidth(), getHeight());
            g2.drawLine(getWidth(), 0, 0, getHeight());

            g2.dispose();
        }

    }

}

警告

g2 = (Graphics2D)getGraphics();是一个非常非常糟糕的想法，并且不是自定义绘制应该如何工作的。

getGraphics只不过是上一次绘制过程中最后绘制的内容的快照，将在下一次绘制过程中失效。

我强烈建议通过阅读Performing Custom Painting和Painting in AWT and Swing来更好地理解Swing中的绘画是如何工作的，以及你应该如何使用它。

用鼠标绘图并不是一个不常见的问题，并且有许多答案。我建议看看其他一些问题/答案，看看如何做到这一点，并采用它们来满足您的需求