在页面上分割字符串

这是我用来在XNA中执行换行的代码。只要将SpriteFont.MeasureString调用转换为适合您的任何调用即可。请注意，这里仍然可能有bug，而且调试起来相当费力。

/// <summary>
/// Extensions to SpriteFont.
/// </summary>
public static class SpriteFontExtensions
{      
    /// <summary>
    /// Abstractly represents a substring by its start index and length.
    /// </summary>
    public struct SubString
    {
        public int StartIndex;
        public int Length;
    }
    private static List<SubString> _lines = new List<SubString>();
    /// <summary>
    /// Wraps a string into sub-string lines, each line no longer (in pixels) than the specified lineWidth.
    /// 
    /// JCF: This is a conversion of Torque3D's GFont::wrapString, available on GitHub. 
    /// </summary>
    public static void WrapString(this SpriteFont font, string inText, int lineWidth, int hangingIndentWidth, List<SubString> outLines)
    {
        // Early out, no text passed to us.
        if (string.IsNullOrEmpty(inText))
            return;
        var strb = new StringBuilder(inText);
        WrapString(font, strb, lineWidth, hangingIndentWidth, outLines);
    }
    /// <summary>
    /// Wraps a string into sub-string lines, each line no longer (in pixels) than the specified lineWidth.
    /// 
    /// JCF: This is a conversion of Torque3D's GFont::wrapString, available on GitHub
    /// </summary>
    public static void WrapString(this SpriteFont font, StringBuilder strb, int lineWidth, int hangingIndentWidth, List<SubString> outLines)
    {
        if (strb.Length == 0)
            return;
        var firstLetterWidth = font.MeasureString(strb[0].ToString()).X;
        // Early out, not even the first letter will fit within the lineWidth available.
        if (firstLetterWidth > lineWidth)
            return;
        var len = strb.Length;
        var startLine = 0;
        for (var i = 0; i < len;)
        {
            startLine = i;
            // loop until the string is too large
            var needsNewLine = false;
            var lineStrWidth = 0;
            for (; i < len; i++)
            {
                if (strb[i] == ''n')
                {
                    needsNewLine = true;
                    break;
                }
                var subStr = strb.Substring(startLine, (i - startLine) + 1);
                lineStrWidth = (int) (font.MeasureString(subStr).X);
                if (outLines.Count > 0)
                    lineStrWidth += hangingIndentWidth;
                if (lineStrWidth > lineWidth)
                {
                    needsNewLine = true;
                    break;
                }
            }
            if (!needsNewLine)
            {
                // we are done!
                var line = new SubString()
                               {
                                   StartIndex = startLine,
                                   Length = i - startLine,
                               };
                outLines.Add(line);
                return;
            }
            var j = 0;
            // Did we hit a hardwrap (newline character) in the string.
            bool hardwrap = (strb[i] == ''n');
            if (hardwrap)
            {
                j = i;
            }
                // determine where to put the newline
                // we need to backtrack until we find a space character 
                // we don't do this for hardwrap(s)
            else
            {
                for (j = i - 1; j >= startLine; j--)
                {
                    if (char.IsSeparator(strb[j]))
                        break;
                }
                if (j < startLine)
                {
                    // the line consists of a single word!              
                    // So, just break up the word
                    j = i - 1;
                }
            }
            // 
            {
                var line = new SubString()
                    {
                        StartIndex = startLine,
                        Length = j - startLine + 1,
                    };
                outLines.Add(line);
                i = line.StartIndex + line.Length;
            }
            // Now we need to increment through any space characters at the
            // beginning of the next line.
            // We don't skip spaces after a hardwrap because they were obviously intended.                
            for (; i < len; i++)
            {
                if (strb[i] == ''n')
                    continue;
                if (char.IsSeparator(strb[i]) && !hardwrap)
                    continue;
                break;
            }
        }
    }
}

}