如何获知在一定宽度内可以显示的字符数量代码,Java代码库,德仔网

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【Java】如何获知在一定宽度内可以显示的字符数量

作者:Dezai.CN / 发布于2011/12/1/ 682

<div> public class MyTest extends JPanel {
 public void paintComponent(Graphics g) {
 super.paintComponent(g);
 Graphics2D g2 = (Graphics2D) g;
 g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING
 , RenderingHints.VALUE_ANTIALIAS_ON);
 String s = "A guide to architecting, designing, and building distributed " +
 "applications with Windows Communication Foundation Windows " +
 "Communication Foundation is the .NET technology that is used " +
 "to build service-oriented applications, exchange messages in " +
 "various communication scenarios, and run workflows.";
 //1. 用多行字符串构造AttributedString，并设置初始化字体
 AttributedString as = new AttributedString(s);
 as.addAttribute(TextAttribute.FONT, new Font("serif", Font.PLAIN, 40));
 //2. 获取文本和属性的迭代器
 AttributedCharacterIterator aci = as.getIterator();
 //3. 通过迭代器和Graphics的字体渲染上下文获取断行测量器
 //该对象可以根据迭代器返回的文本信息和FontMetrics等属性值，再结合当前
 //Graphics的渲染上下文计算出每行可以显示的文本。
 LineBreakMeasurer lbm = new LineBreakMeasurer(aci,g2.getFontRenderContext());
 //4. 结合JPanel的内边属性，计算每行显示的起始x坐标和宽度
 Insets insets = getInsets();
 float wrappingWidth = getSize().width - insets.left - insets.right;
 float x = insets.left;
 float y = insets.top;
 //5. 开始计算每行可以显示的字符数量同时渲染本行的字符串。
 //getPosition()返回当前正在渲染的字符在整个字符串中的索引值。
 while (lbm.getPosition() < aci.getEndIndex()) {
 //5.1 LineBreakMeasurer基于参数传入的宽度，并结合字体的Metrics，
 //获取当前行应该渲染的文本布局对象。
 TextLayout textLayout = lbm.nextLayout(wrappingWidth);
 //5.2 y + ascent得到的是基线y坐标，并从该点开始绘制本行的文本
 y += textLayout.getAscent();
 textLayout.draw(g2, x, y);
 //5.3 baseline + descent + leading得到下一行的ascent的y坐标
 y += textLayout.getDescent() + textLayout.getLeading();
 //5.4 将baseline的x坐标回归到行起点
 x = insets.left;
 }
 }
 public static void main(String[] args) {
 JFrame frame = new JFrame();
 frame.setTitle("Show String with Multiline.");
 frame.addWindowListener(new WindowAdapter() {
 public void windowClosing(WindowEvent e) {
 System.exit(0);
 }
 });
 frame.setContentPane(new MyTest());
 frame.setSize(800, 500);
 frame.setVisible(true);
 }
 }

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