Font Structure

[aleks]

A some Windows bitmap/raster font metrics
support.microsoft.com/kb/32667/

 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _


 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
                    A
                   A
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
                  A
                 A A
                A   A
 _ _ _ _ _ _   A     A   _ _ _  gggg g _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
              AAAAAAAAA        g    gg
             A         A       g     g
            A           A      g    gg
 _ _ _ _ _ A_ _ _ _ _ _ _A _ _  gggg g _ _ _ _ _ _ _ _ _ Baseline_ _
                                     g                |
                               g     g                |
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  ggggg  _ _ _ _ _ _ _ _|
                                                      |
                                    External Leading -|
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|
        |           A       |             |           |
                   A    Internal Leading -|           |
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|           |- Line height
        |         A         |             |           |
        |        A A        |             |           |
        |       A   A       |             |- Ascent   |
        |      A     A      |   gggg g    |           |
        |     AAAAAAAAA     |  g    gg    |           |
    Em -|    A         A    |  g     g    |           |
        |   A           A   |  g    gg    |           |
        |_ A_ _ _ _ _ _ _A _|_  gggg g _ _|_ _ _ _ _ _|_ _ _ _ _ _ _
        |                   |        g    |           |
        |                   |  g     g    |- Descent  |
 _ _ _ _|_ _ _ _ _ _ _ _ _ _|_  ggggg  _ _|_ _ _ _ _ _|
                                                      |
                                    External Leading -|
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|
        |           A       |             |           |
        |          A        |             |           |
        |                   |             |           |- Line height
        |         A         |             |           |
        |        A A        |             |           |
        |       A   A       |             |- Ascent   |
        |      A     A      |   gggg g    |           |
Height -|     AAAAAAAAA     |  g    gg    |           |
        |    A         A    |  g     g    |           |
        |   A           A   |  g    gg    |           |
        |_ A_ _ _ _ _ _ _A _|_  gggg g _ _|_ _ _ _ _ _|_ _ _ _ _ _ _
        |                   |        g    |           |
        |                   |  g     g    |- Descent  |
 _ _ _ _|_ _ _ _ _ _ _ _ _ _|_  ggggg  _ _|_ _ _ _ _ _|
        |                   |             |
        | <-    Width    -> | <- Width -> |

Ascent - glyph bitmaps ascent from (or relative to) baseline.
Descent - glyph bitmaps descent from (or relative to) baseline.
Height or Cell height - height of glyph bitmaps.

[ Cell height = Ascent + Descent ]

Internal Leading - vertical space of diacritical marks (accents).
External Leading or Line spacing or Line gap - vertical space/gap between adjoining glyph bitmaps.
Internal Leading and External Leading are optional parameters.

Em or Character Height - glyph bitmaps height without diacritical marks.

[ Em = Cell height - Internal Leading ]

Line height or Lead (equivalent to the line-height:normal in the HTML) - vertical space/interval between adjoining baselines or baseline-to-baseline distance.

[ Line height = Cell height + External Leading ]

Width - width of glyph bitmaps.
Avg Width - average width of glyph bitmaps (relevant to non-monospaced fonts).
Max Width - maximum width of glyph bitmaps (relevant to non-monospaced fonts).


Correct me if I'm in something wrong.