字符占据的宽和高的像素数量

Java字体绘制测试

最新推荐文章于 2021-03-18 01:45:00 发布

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本文介绍了一个简单的Java Swing应用程序，用于测试不同字体下文本的显示效果。该程序通过计算并显示字符串'Hello, World!'的宽度和高度来演示如何在Swing组件上精确地绘制文本。此外，还展示了如何使用Graphics2D API来绘制文本、基线和包围框。

package swing;

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;

import javax.swing.JComponent;
import javax.swing.JFrame;

/**
* 字符占据的宽和高的像素数量
*/
public class FontTest {
public static void main(String[] args) {
  EventQueue.invokeLater(new Runnable() {
   @Override
   public void run() {
    FontFrame frame = new FontFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
   }
  });
}
}

class FontFrame extends JFrame {
public FontFrame() {
  this.setTitle("FontTest");
  this.setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

  FontComponent component = new FontComponent();
  this.add(component);
}

public static final int DEFAULT_WIDTH = 300;
public static final int DEFAULT_HEIGHT = 200;
}

class FontComponent extends JComponent {
@Override
public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D) g;

  String message = "Hello, World!";

  Font f = new Font("Serif", Font.BOLD, 36);
  g2.setFont(f);

  FontRenderContext context = g2.getFontRenderContext();
  Rectangle2D bounds = f.getStringBounds(message, context);

  double x = (this.getWidth() - bounds.getWidth()) / 2;
  double y = (this.getHeight() - bounds.getHeight()) / 2;

  double ascent = -bounds.getY();
  double baseY = y + ascent;

  //画字符串
  g2.drawString(message, (int)x, (int)baseY);

  g2.setPaint(Color.LIGHT_GRAY);
  //画基线
  g2.draw(new Line2D.Double(x, baseY, x + bounds.getWidth(), baseY));
  //画矩形
  Rectangle2D rect = new Rectangle2D.Double(x, y, bounds.getWidth(), bounds.getHeight());
  g2.draw(rect);
}
}