画出多行文本
你可以使用TextLayout和 java.awt.LineBreakMeasurer类画出一段式样文本,下面的这个例子使用了LineBreakMeasurer对象,在组件允许的宽度范围内,创建并画出多行文本(文本布局)。由TextLayout类中的getAscent
和 getDescent方法返回的字体度量信息,用来定位组件中的文本的行的大小。文本保存为AttributedCharacterIterator对象,这样字体和及其大小信息可以一起存储起来。
此处为LineBreakSample.java例子的完整的源代码。SampleUtils.java
类包含了LineBreakSample 应用程序所需要显示的文本。
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注意点: LineBreakSample应用程序支持非英语的文本。请见第四课中对非英语文本的支持的章节。
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public class LineBreakSample extends Component {
private LineBreakMeasurer lineMeasurer;
private int paragraphStart;
private int paragraphEnd;
public LineBreakSample (AttributedCharacterIterator paragraph) {
FontRenderContext frc = SampleUtils.getDefaultFontRenderContext();
paragraphStart = paragraph.getBeginIndex();
paragraphEnd = paragraph.getEndIndex();
lineMeasurer = new LineBreakMeasurer(paragraph, frc);
}
public void paint(Graphics g) {
Graphics2D graphics2D = (Graphics2D) g;
Dimension size = getSize();
float formatWidth = (float) size.width;
float drawPosY = 0;
lineMeasurer.setPosition(paragraphStart);
while (lineMeasurer.getPosition() < paragraphEnd) {
TextLayout layout = lineMeasurer.nextLayout(formatWidth);
drawPosY += layout.getAscent();
float drawPosX;
if (layout.isLeftToRight()) {
drawPosX = 0;
}
else {
drawPosX = formatWidth - layout.getAdvance();
}
layout.draw(graphics2D, drawPosX, drawPosY);
drawPosY += layout.getDescent() +layout.getLeading();
}
}
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