最好的自动换行算法？

自动换行是现代文本编辑器中必备功能之一.

你知道如何处理自动换行吗？自动换行的最佳算法是什么？

更新:如果文本是几百万行,我怎么能快速进行自动换行？

更新:为什么我需要解决方案？因为我的项目必须绘制具有各种缩放级别和同时漂亮外观的文本.

已更新:运行环境是Windows Mobile设备.最大600MHz速度,内存尺寸非常小.

更新:我应该如何处理行信息？我们假设原始数据有三行.

THIS IS LINE 1.
THIS IS LINE 2.
THIS IS LINE 3.

分词后的文字将显示如下:

THIS IS
LINE 1.
THIS IS
LINE 2.
THIS IS
LINE 3.

我应该再分配3行吗？还是其他任何建议？

这是我用C#编写的自动换行算法.翻译成其他语言应该相当容易(除了可能IndexOfAny).

static char[] splitChars = new char[] { ' ', '-', '\t' };

private static string WordWrap(string str, int width)
{
    string[] words = Explode(str, splitChars);

    int curLineLength = 0;
    StringBuilder strBuilder = new StringBuilder();
    for(int i = 0; i < words.Length; i += 1)
    {
        string word = words[i];
        // If adding the new word to the current line would be too long,
        // then put it on a new line (and split it up if it's too long).
        if (curLineLength + word.Length > width)
        {
            // Only move down to a new line if we have text on the current line.
            // Avoids situation where wrapped whitespace causes emptylines in text.
            if (curLineLength > 0)
            {
                strBuilder.Append(Environment.NewLine);
                curLineLength = 0;
            }

            // If the current word is too long to fit on a line even on it's own then
            // split the word up.
            while (word.Length > width)
            {
                strBuilder.Append(word.Substring(0, width - 1) + "-");
                word = word.Substring(width - 1);

                strBuilder.Append(Environment.NewLine);
            }

            // Remove leading whitespace from the word so the new line starts flush to the left.
            word = word.TrimStart();
        }
        strBuilder.Append(word);
        curLineLength += word.Length;
    }

    return strBuilder.ToString();
}

private static string[] Explode(string str, char[] splitChars)
{
    List parts = new List();
    int startIndex = 0;
    while (true)
    {
        int index = str.IndexOfAny(splitChars, startIndex);

        if (index == -1)
        {
            parts.Add(str.Substring(startIndex));
            return parts.ToArray();
        }

        string word = str.Substring(startIndex, index - startIndex);
        char nextChar = str.Substring(index, 1)[0];
        // Dashes and the likes should stick to the word occuring before it. Whitespace doesn't have to.
        if (char.IsWhiteSpace(nextChar))
        {
            parts.Add(word);
            parts.Add(nextChar.ToString());
        }
        else
        {
            parts.Add(word + nextChar);
        }

        startIndex = index + 1;
    }
}

Function WordWrap (inputString, width)
    Trim the input string of leading and trailing spaces.

    If the trimmed string's length is <= the width,
        Return the trimmed string.
    Else,
        Find the index of the last space in the trimmed string, starting at width

        If there are no spaces, use the width as the index.

        Split the trimmed string into two pieces at the index.

        Trim trailing spaces from the portion before the index,
        and leading spaces from the portion after the index.

        Concatenate and return:
          the trimmed portion before the index,
          a line break,
          and the result of calling WordWrap on the trimmed portion after
            the index (with the same width as the original call).