How do I implement word wrap?

问题:

XNA has Spritefont class, which has a MeasureString method, which can return the Width and Height of a string. I'm trying to understand how to create a method that will efficiently return a string with Environment.Newline inserted in the right places, so that if fits a certain Width and Height (Rectangle is used as a parameter for that).

回答1:

I found following code: XNA - Basic Word Wrapping

public string WrapText(SpriteFont spriteFont, string text, float maxLineWidth)
{
    string[] words = text.Split(' ');
    StringBuilder sb = new StringBuilder();
    float lineWidth = 0f;
    float spaceWidth = spriteFont.MeasureString(" ").X;

    foreach (string word in words)
    {
        Vector2 size = spriteFont.MeasureString(word);

        if (lineWidth + size.X < maxLineWidth)
        {
            sb.Append(word + " ");
            lineWidth += size.X + spaceWidth;
        }
        else
        {
            sb.Append("\n" + word + " ");
            lineWidth = size.X + spaceWidth;
        }
    }

    return sb.ToString();
}

回答2:

To add to Alina's answer, here is an extended version of that function, that will also linebreak single words that are longer than maxLineWidth

    public static string WrapText(SpriteFont font, string text, float maxLineWidth)
    {
        string[] words = text.Split(' ');
        StringBuilder sb = new StringBuilder();
        float lineWidth = 0f;
        float spaceWidth = font.MeasureString(" ").X;

        foreach (string word in words)
        {
            Vector2 size = font.MeasureString(word);

            if (lineWidth + size.X < maxLineWidth)
            {
                sb.Append(word + " ");
                lineWidth += size.X + spaceWidth;
            }
            else
            {
                if (size.X > maxLineWidth)
                {
                    if (sb.ToString() == "")
                    {
                        sb.Append(WrapText(font, word.Insert(word.Length / 2, " ") + " ", maxLineWidth));
                    }
                    else
                    {
                        sb.Append("\n" + WrapText(font, word.Insert(word.Length / 2, " ") + " ", maxLineWidth));
                    }
                }
                else
                {
                    sb.Append("\n" + word + " ");
                    lineWidth = size.X + spaceWidth;
                }
            }
        }

        return sb.ToString();
    }

回答3:

To handle a block of text with carriage returns you need to modify the code as below:

  public static string WrapText(SpriteFont font, string text, float maxLineWidth)
    {
        string[] words = text.Split(' ');
        StringBuilder sb = new StringBuilder();
        float lineWidth = 0f;
        float spaceWidth = font.MeasureString(" ").X;

        foreach (string word in words)
        {
            Vector2 size = font.MeasureString(word);

            if (word.Contains("\r"))
            {
                lineWidth = 0f;
                sb.Append("\r \r" );
            }

            if (lineWidth + size.X < maxLineWidth )
            {
                sb.Append(word + " ");
                lineWidth += size.X + spaceWidth;
            }

            else
            {
                if (size.X > maxLineWidth )
                {
                    if (sb.ToString() == " ")
                    {
                        sb.Append(WrapText(font, word.Insert(word.Length / 2, " ") + " ", maxLineWidth));
                    }
                    else
                    {
                        sb.Append("\n" + WrapText(font, word.Insert(word.Length / 2, " ") + " ", maxLineWidth));
                    }
                }
                else
                {
                    sb.Append("\n" + word + " ");
                    lineWidth = size.X + spaceWidth;
                }
            }
        }

        return sb.ToString();
    }