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If you have a paragraph of styled text that you would like to fit within a specific width, you can useLineBreakMeasurer
, which allows styled text to be broken into lines that fit within a particular visual advance. As you learned in the Displaying Graphics with Graphics2D trail, aTextLayout
object represents unchangeable, styled character data, but it also allows access to layout information. ThegetAscent
andgetDescent
methods ofTextLayout
return information about the font that is used to position the lines in the component. The text is stored as anAttributedCharacterIterator
so the font and point size attributes can be stored with the text.
The following applet positions a paragraph of styled text within a component, usingLineBreakMeasurer
,TextLayout
andAttributedCharacterIterator
.
The complete code for this program is in
This is a picture of the applet's GUI. To run the applet, click the picture. The applet will appear in a new browser window.LineBreakSample.java
.The following code creates an iterator with the string
vanGogh
. The start and end of the iterator is retrieved and a newLineBreakMeasurer
is created from the iterator.The size of the window is used to determine where the line should break and aAttributedCharacterIterator paragraph = vanGogh.getIterator(); paragraphStart = paragraph.getBeginIndex(); paragraphEnd = paragraph.getEndIndex(); lineMeasurer = new LineBreakMeasurer(paragraph, new FontRenderContext(null, false, false));TextLayout
object is created for each line in the paragraph.Dimension size = getSize(); float formatWidth = (float) size.width; float drawPosY = 0; lineMeasurer.setPosition(paragraphStart); while (lineMeasurer.getPosition() < paragraphEnd) { TextLayout layout = lineMeasurer.nextLayout(formatWidth); // Move y-coordinate by the ascent of the layout. drawPosY += layout.getAscent(); /* Compute pen x position. If the paragraph is right-to-left, we want to align the TextLayouts to the right edge of the panel. */ float drawPosX; if (layout.isLeftToRight()) { drawPosX = 0; } else { drawPosX = formatWidth - layout.getAdvance(); } // Draw the TextLayout at (drawPosX, drawPosY). layout.draw(graphics2D, drawPosX, drawPosY); // Move y-coordinate in preparation for next layout. drawPosY += layout.getDescent() + layout.getLeading(); }
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