/* Utilities.java --
Copyright (C) 2004 Free Software Foundation, Inc.
This file is part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
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02111-1307 USA.
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package javax.swing.text;
import java.awt.FontMetrics;
import java.awt.Graphics;
/**
* A set of utilities to deal with text. This is used by several other classes
* inside this package.
*
* @author Roman Kennke <roman@ontographics.com>
*/
public class Utilities
{
/**
* The length of the char buffer that holds the characters to be drawn.
*/
private static final int BUF_LENGTH = 64;
/**
* Creates a new <code>Utilities</code> object.
*/
public Utilities()
{
// Nothing to be done here.
}
/**
* Draws the given text segment. Contained tabs and newline characters
* are taken into account. Tabs are expanded using the
* specified {@link TabExpander}.
*
* @param s the text fragment to be drawn.
* @param x the x position for drawing.
* @param y the y position for drawing.
* @param g the {@link Graphics} context for drawing.
* @param e the {@link TabExpander} which specifies the Tab-expanding
* technique.
* @param startOffset starting offset in the text.
* @return the x coordinate at the end of the drawn text.
*/
public static final int drawTabbedText(Segment s, int x, int y, Graphics g,
TabExpander e, int startOffset)
{
// This buffers the chars to be drawn.
char[] buffer = s.array;
// The current x and y pixel coordinates.
int pixelX = x;
int pixelY = y;
// The font metrics of the current selected font.
FontMetrics metrics = g.getFontMetrics();
int ascent = metrics.getAscent();
int pixelWidth = 0;
int pos = 0;
int len = 0;
for (int offset = s.offset; offset < (s.offset + s.count); ++offset)
{
char c = buffer[offset];
if (c == '\t' || c == '\n')
{
if (len > 0) {
g.drawChars(buffer, pos, len, pixelX, pixelY + ascent);
pixelX += pixelWidth;
pixelWidth = 0;
}
pos = offset+1;
len = 0;
}
switch (c)
{
case '\t':
// In case we have a tab, we just 'jump' over the tab.
// When we have no tab expander we just use the width of ' '.
if (e != null)
pixelX = (int) e.nextTabStop((float) pixelX,
startOffset + offset - s.offset);
else
pixelX += metrics.charWidth(' ');
break;
case '\n':
// In case we have a newline, we must jump to the next line.
pixelY += metrics.getHeight();
pixelX = x;
break;
default:
++len;
pixelWidth += metrics.charWidth(buffer[offset]);
break;
}
}
if (len > 0)
g.drawChars(buffer, pos, len, pixelX, pixelY + ascent);
return pixelX;
}
/**
* Determines the width, that the given text <code>s</code> would take
* if it was printed with the given {@link java.awt.FontMetrics} on the
* specified screen position.
* @param s the text fragment
* @param metrics the font metrics of the font to be used
* @param x the x coordinate of the point at which drawing should be done
* @param e the {@link TabExpander} to be used
* @param startOffset the index in <code>s</code> where to start
* @returns the width of the given text s. This takes tabs and newlines
* into account.
*/
public static final int getTabbedTextWidth(Segment s, FontMetrics metrics,
int x, TabExpander e,
int startOffset)
{
// This buffers the chars to be drawn.
char[] buffer = s.array;
// The current x coordinate.
int pixelX = x;
// The current maximum width.
int maxWidth = 0;
for (int offset = s.offset; offset < (s.offset + s.count); ++offset)
{
switch (buffer[offset])
{
case '\t':
// In case we have a tab, we just 'jump' over the tab.
// When we have no tab expander we just use the width of 'm'.
if (e != null)
pixelX = (int) e.nextTabStop((float) pixelX,
startOffset + offset - s.offset);
else
pixelX += metrics.charWidth(' ');
break;
case '\n':
// In case we have a newline, we must 'draw'
// the buffer and jump on the next line.
pixelX += metrics.charWidth(buffer[offset]);
maxWidth = Math.max(maxWidth, pixelX - x);
pixelX = x;
break;
default:
// Here we draw the char.
pixelX += metrics.charWidth(buffer[offset]);
break;
}
}
// Take the last line into account.
maxWidth = Math.max(maxWidth, pixelX - x);
return maxWidth;
}
}