Question

我想在＆＃34;公共无效油漆（图形g）{}＆＃34;中绘制出一个JLabel。还有那些东西。如何从类外部（在main方法中）获取JLabel并在paint方法中绘制它？

static JLabel drawThisOut = new JLabel("draw this out");
public static void main(String[] args) {
    class paintJLabel extends JComponent {
         public void paint(Graphics g) {
             //what goes here to draw the JLabel?????
         }
    }
}

不，我不能只使用常规JLabel而不是将其绘制出来。我需要在JLabel上绘制其他东西，我认为这是最有效的方法。（有更有效的方法吗？）任何帮助都将非常感激。请具体说明。谢谢！

Answer 1

在“最简单”的术语中，您可以使用某种Border，以下是自定义的圆形边框，但概念相对简单

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.geom.RoundRectangle2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.AbstractBorder;

public class Test {

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

    public Test() {
        EventQueue.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 {

        public TestPane() {
            setLayout(new GridBagLayout());
            JLabel label = new JLabel("This is a test");
            label.setBorder(new RoundedBorder(Color.BLACK, 20));
            add(label);
        }

    }

    public class RoundedBorder extends AbstractBorder {

        private final Color color;
        private final int gap;

        public RoundedBorder(Color c, int g) {
            color = c;
            gap = g;
        }

        @Override
        public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
            g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
            g2d.setColor(color);
            g2d.draw(new RoundRectangle2D.Double(x, y, width - 1, height - 1, gap, gap));
            g2d.dispose();
        }

        @Override
        public Insets getBorderInsets(Component c) {
            return (getBorderInsets(c, new Insets(gap, gap, gap, gap)));
        }

        @Override
        public Insets getBorderInsets(Component c, Insets insets) {
            insets.left = insets.top = insets.right = insets.bottom = gap / 2;
            return insets;
        }

        @Override
        public boolean isBorderOpaque() {
            return false;
        }
    }
}

您还可以使用自定义组件。这为您提供了能够用自己的背景颜色“填充”形状的额外好处，但是，基本上是相同的东西

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.geom.RoundRectangle2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.AbstractBorder;
import javax.swing.border.EmptyBorder;

public class Test {

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

    public Test() {
        EventQueue.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 {

        public TestPane() {
            setLayout(new GridBagLayout());
            JLabel label = new JLabel("This is a test");
            label.setBorder(new EmptyBorder(10, 10, 10, 10));
            RoundedPane pane = new RoundedPane();
            pane.add(label);
            add(pane);
        }

    }

    public class RoundedPane extends JPanel {

        public RoundedPane() {
            setLayout(new BorderLayout());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
            g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
            g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
            g2d.setColor(Color.BLACK);
            g2d.draw(new RoundRectangle2D.Double(0, 0, getWidth() - 1, getHeight() - 1, 20, 20));
            g2d.dispose();
        }

    }
}

如何绘制JLabel？ - Java

1 个答案: