Understanding Font Information

When opening a font Altsoft Font Type Master automatically recognizes its type and displays the contents of the font in the "Basic Font Browser" tree view as shown below:

If a font contains encodings there are four subnodes in the current font tree node. Otherwise (for CID-keyed fonts) there are only three of them. A double-click on any available subnode introduces detailed information about:

  • Encoding
  • Glyphs
  • Names
  • Metrics

The following sections contain the description of detailed font information:

Using Properties Window

Every object mentioned in the following sections (e.g. glyph, glyph outline element, name, metric or character encoding) can be characterized with certain parameters. The list of basic object features can be viewed or edited in "Properties" window. To open this window press ("Properties") button or select "Properties" from "View" menu:

The list of certain object properties will be loaded. Read-only data is highlighted with gray color, features allowed for editing are marked with bold typeface:

  • Font Properties:

  • Character Encoding Properties:
    • TrueType and OpenType fonts:

    • Type 2 and CFF Multiple Master fonts:

    • Type 1, Type 42 and PostScript Multiple Master fonts:

  • Glyph Properties:
    • TrueType and OpenType fonts:

    • Type 2 and CFF Multiple Master fonts:

    • Type 1, Type 42 and PostScript Multiple Master fonts:

  • Metrics Properties:
  • Outline Properties:
    • Points:

    • Lines:

    • Composite Glyph Components:

Font Characteristics

A font is usually referred to as a collection of glyphs (pictures of abstract characters). Here is the explanation of the main glyph characteristics:

  • Character Code (Char Code, Character ID) is relevant to one-byte fonts such as PS Type 1, CFF Type 1, Multiple Master, and Type 42. This parameter is a nonnegative integer from the interval 0..255 that is put in correspondence to the glyph's charstring via the built-in encoding of the font.
  • Charstring Name (Char Name) is relevant to one-byte fonts such as PS Type 1, PS Multiple Master Type 1, and Type 42. This parameter is the main glyph characteristics, which determines the glyph completely. In these fonts glyphs are addressed by their charstring names, which are internal 'indices' of glyphs inside the font. To every character code corresponds one and only one charstring name via encoding built-in in the font. Note that while there is a maximum of 256 character codes that can be used to address glyphs, the actual font may contain much more glyph charstrings, so that many charstring names will not correspond to any particular character code. By convention their character code is equal to -1.
  • String Identifier (SID) is analogous to Character Name but is relevant only to CFF Type 1 fonts and CFF Multiple Master Type 1 fonts.
  • Glyph Identifier (GID) (TrueType) and CharstringID (CID) (CFF fonts). These numbers are internal indices that address glyphs inside TrueType-based fonts and CFF-based fonts respectively. Their function in Type 1-based fonts is performed by charstring names.
  • Encoding values (TrueType based fonts). Every TrueType font has a 'cmap' table. This table contains information on the method of addressing glyphs in the font according to different platforms and language-specific environments. 'cmap' table consists of several subtables that are characterized by a pair of numbers (Platform Id, Specific Id). For example, the value (1,0) means “Macintosh Roman” environment, while (3,1) means “Microsoft Unicode”. Thus, the integer in the column (3,1) equals to the Microsoft Unicode value of that glyph.
  • Bounding Box (BBox) of the glyph is the array of four numbers [Xmin, Ymin, Xmax, Ymax] that denote the minimal rectangle in the glyph coordinate system that entirely contains the glyph. The point with coordinates (Xmin,Ymin) corresponds to the lower left-hand corner of that rectangle, while the point (Xmax, Ymax) corresponds to the upper right-hand corner of the rectangle. BBox is used for calculating the size of a string of glyphs as well as for determining whether the glyph fits into a given area. Note that the glyph coordinate system has different scales in different font types. The TrueType-based fonts use the glyph space graded from 0 to 2048 whereas the Type 1 based fonts use the scale graded from 0 to 1000.
  • Width of the glyph is the integer number that expresses the amount of space in the x-direction that the glyph occupies. It is measured in the glyph coordinate system, which is graded from 0 to 2048 for TrueType based fonts and from 0 to 1000 for Type 1 based fonts. Note that for italic (oblique) fonts some parts of the glyph may hang out of the interval 0..Width, so using Widths for calculating string size may prove erroneous. Use glyph BBox to this end.
  • ItalicAngle characterizes the angle of inclination of italic typeface of the font.
For more information on font definition, font types and glyph characteristics consult Online FTMBase help