Wrap string according to FontMetrics
import java.awt.FontMetrics;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
/**
* Globally available utility classes, mostly for string manipulation.
*
* @author Jim Menard, <a href="mailto:jimm@io.com">jimm@io.com</a>
*/
public class StringUtils {
/**
* Returns an array of strings, one for each line in the string after it has
* been wrapped to fit lines of <var>maxWidth</var>. Lines end with any of
* cr, lf, or cr lf. A line ending at the end of the string will not output a
* further, empty string.
* <p>
* This code assumes <var>str</var> is not <code>null</code>.
*
* @param str
* the string to split
* @param fm
* needed for string width calculations
* @param maxWidth
* the max line width, in points
* @return a non-empty list of strings
*/
public static List wrap(String str, FontMetrics fm, int maxWidth) {
List lines = splitIntoLines(str);
if (lines.size() == 0)
return lines;
ArrayList strings = new ArrayList();
for (Iterator iter = lines.iterator(); iter.hasNext();)
wrapLineInto((String) iter.next(), strings, fm, maxWidth);
return strings;
}
/**
* Given a line of text and font metrics information, wrap the line and add
* the new line(s) to <var>list</var>.
*
* @param line
* a line of text
* @param list
* an output list of strings
* @param fm
* font metrics
* @param maxWidth
* maximum width of the line(s)
*/
public static void wrapLineInto(String line, List list, FontMetrics fm, int maxWidth) {
int len = line.length();
int width;
while (len > 0 && (width = fm.stringWidth(line)) > maxWidth) {
// Guess where to split the line. Look for the next space before
// or after the guess.
int guess = len * maxWidth / width;
String before = line.substring(0, guess).trim();
width = fm.stringWidth(before);
int pos;
if (width > maxWidth) // Too long
pos = findBreakBefore(line, guess);
else { // Too short or possibly just right
pos = findBreakAfter(line, guess);
if (pos != -1) { // Make sure this doesn't make us too long
before = line.substring(0, pos).trim();
if (fm.stringWidth(before) > maxWidth)
pos = findBreakBefore(line, guess);
}
}
if (pos == -1)
pos = guess; // Split in the middle of the word
list.add(line.substring(0, pos).trim());
line = line.substring(pos).trim();
len = line.length();
}
if (len > 0)
list.add(line);
}
/**
* Returns the index of the first whitespace character or '-' in <var>line</var>
* that is at or before <var>start</var>. Returns -1 if no such character is
* found.
*
* @param line
* a string
* @param start
* where to star looking
*/
public static int findBreakBefore(String line, int start) {
for (int i = start; i >= 0; --i) {
char c = line.charAt(i);
if (Character.isWhitespace(c) || c == '-')
return i;
}
return -1;
}
/**
* Returns the index of the first whitespace character or '-' in <var>line</var>
* that is at or after <var>start</var>. Returns -1 if no such character is
* found.
*
* @param line
* a string
* @param start
* where to star looking
*/
public static int findBreakAfter(String line, int start) {
int len = line.length();
for (int i = start; i < len; ++i) {
char c = line.charAt(i);
if (Character.isWhitespace(c) || c == '-')
return i;
}
return -1;
}
/**
* Returns an array of strings, one for each line in the string. Lines end
* with any of cr, lf, or cr lf. A line ending at the end of the string will
* not output a further, empty string.
* <p>
* This code assumes <var>str</var> is not <code>null</code>.
*
* @param str
* the string to split
* @return a non-empty list of strings
*/
public static List splitIntoLines(String str) {
ArrayList strings = new ArrayList();
int len = str.length();
if (len == 0) {
strings.add("");
return strings;
}
int lineStart = 0;
for (int i = 0; i < len; ++i) {
char c = str.charAt(i);
if (c == '\r') {
int newlineLength = 1;
if ((i + 1) < len && str.charAt(i + 1) == '\n')
newlineLength = 2;
strings.add(str.substring(lineStart, i));
lineStart = i + newlineLength;
if (newlineLength == 2) // skip \n next time through loop
++i;
} else if (c == '\n') {
strings.add(str.substring(lineStart, i));
lineStart = i + 1;
}
}
if (lineStart < len)
strings.add(str.substring(lineStart));
return strings;
}
}
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