Java Font Text Width wrap(String str, FontMetrics fm, int maxWidth)

Description

Returns an array of strings, one for each line in the string after it has been wrapped to fit lines of maxWidth.

License

Apache License

Parameter

Parameter	Description
str	the string to split
fm	needed for string width calculations
maxWidth	the max line width, in points

Return

a non-empty list of strings

Declaration

public static List<String> wrap(String str, FontMetrics fm, int maxWidth) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.awt.FontMetrics;
import java.util.*;

public class Main {
    /**//from www  .  j a v  a2s. co m
     * 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<String> wrap(String str, FontMetrics fm, int maxWidth) {
        List<String> lines = splitIntoLines(str);
        if (lines.size() == 0)
            return lines;

        ArrayList<String> strings = new ArrayList<String>();
        for (String line : lines)
            wrapLineInto(line, strings, fm, maxWidth);
        return strings;
    }

    /**
     * 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<String> splitIntoLines(String str) {
        ArrayList<String> strings = new ArrayList<String>();

        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;
    }

    /**
     * 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<String> 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;
    }
}

Related

1. stringWidth(final FontMetrics fm, final String string)
2. stringWidth(Graphics g, String s)
3. stringWidth(Graphics2D g, String s)
4. stringWidth(java.awt.Font font, String string)
5. stringWidth(String text, Font font)
6. wrapLineInto(String line, List list, FontMetrics fm, int maxWidth)