Letter.cs

namespace UglyToad.PdfPig.Content
{
    using Core;
    using Graphics.Colors;
    using PdfFonts;

    /// <summary>
    /// A glyph or combination of glyphs (characters) drawn by a PDF content stream.
    /// </summary>
    public class Letter
    {
        /// <summary>
        /// The text for this letter or unicode character.
        /// </summary>
        public string Value { get; }

        /// <summary>
        /// Text orientation of the letter.
        /// </summary>
        public TextOrientation TextOrientation { get; }

        /// <summary>
        /// The placement position of the character in PDF space. See <see cref="StartBaseLine"/>
        /// </summary>
        public PdfPoint Location => StartBaseLine;

        /// <summary>
        /// The placement position of the character in PDF space (the start point of the baseline). See <see cref="Location"/>
        /// </summary>
        public PdfPoint StartBaseLine { get; }

        /// <summary>
        /// The end point of the baseline.
        /// </summary>
        public PdfPoint EndBaseLine { get; }

        /// <summary>
        /// The width occupied by the character within the PDF content.
        /// </summary>
        public double Width { get; }

        /// <summary>
        /// Position of the bounding box for the glyph, this is the box surrounding the visible glyph as it appears on the page.
        /// For example letters with descenders, p, j, etc., will have a box extending below the <see cref="Location"/> they are placed at.
        /// The width of the glyph may also be more or less than the <see cref="Width"/> allocated for the character in the PDF content.
        /// </summary>
        public PdfRectangle GlyphRectangle { get; }

        /// <summary>
        /// Size as defined in the PDF file. This is not equivalent to font size in points but is relative to other font sizes on the page.
        /// </summary>
        public double FontSize { get; }

        /// <summary>
        /// The name of the font.
        /// </summary>
        public string FontName => Font?.Name;

        /// <summary>
        /// Details about the font for this letter.
        /// </summary>
        public FontDetails Font { get; }

        /// <summary>
        /// The color of the letter.
        /// </summary>
        public IColor Color { get; }

        /// <summary>
        /// The size of the font in points.
        /// <para>This is considered experimental because the calculated value is incorrect for some documents at present.</para>
        /// </summary>
        public double PointSize { get; }

        /// <summary>
        /// Sequence number of the ShowText operation that printed this letter.
        /// </summary>
        public int TextSequence { get; }

        /// <summary>
        /// Create a new letter to represent some text drawn by the Tj operator.
        /// </summary>
        public Letter(string value, PdfRectangle glyphRectangle,
            PdfPoint startBaseLine,
            PdfPoint endBaseLine,
            double width,
            double fontSize,
            FontDetails font,
            IColor color,
            double pointSize,
            int textSequence)
        {
            Value = value;
            GlyphRectangle = glyphRectangle;
            StartBaseLine = startBaseLine;
            EndBaseLine = endBaseLine;
            Width = width;
            FontSize = fontSize;
            Font = font;
            Color = color ?? GrayColor.Black;
            PointSize = pointSize;
            TextSequence = textSequence;
            TextOrientation = GetTextOrientation();
        }

        private TextOrientation GetTextOrientation()
        {
            if (System.Math.Abs(StartBaseLine.Y - EndBaseLine.Y) < 10e-5)
            {
                if (StartBaseLine.X > EndBaseLine.X)
                {
                    return TextOrientation.Rotate180;
                }

                return TextOrientation.Horizontal;
            }

            if (System.Math.Abs(StartBaseLine.X - EndBaseLine.X) < 10e-5)
            {
                if (StartBaseLine.Y > EndBaseLine.Y)
                {
                    return TextOrientation.Rotate90;
                }

                return TextOrientation.Rotate270;
            }

            return TextOrientation.Other;
        }

        /// <summary>
        /// Produces a string representation of the letter and its position.
        /// </summary>
        public override string ToString()
        {
            return $"{Value} {Location} {FontName} {PointSize}";
        }
    }
}