PDFlib Text Extraction Toolkit (TET) Manual

width
(x, y)
beta
fontsize
baseline
fontsize
(x, y)
alpha
width
Fig. 6.3
Glyph metrics for horizontal and vertical writing mode
in TET’s default coordinate system (topdown=false)
group of artificial characters comprises the continuation of a multi-character sequence
(e.g. the second character of a ligature) and inserted separator characters. For
artificial characters the position (x, y) will specify the endpoint of the most recent
real character, the width is 0, and all other fields except uv are those of the most recent
real character. The endpoint is the point (x, y) plus the width added in direction
alpha (in horizontal writing mode) or plus the fontsize in direction -90˚ (in vertical
writing mode).
> The unknown field will usually be false (in C and C++: 0), but has a value of true (in C
and C++: 1) if the original glyph could not be mapped to Unicode and has therefore
been replaced with the character specified in the unknownchar option. Using this
field you can distinguish real document content from replaced characters if you
specified a common character as unknownchar, such as a question mark or space.
> The attributes field contains information about the subscript, superscript, dropcap,
or shadow status of the glyph as determined by TET’s content analysis algorithms.
> The (x, y) fields specify the position of the glyph’s reference point, which is the lower
left corner of the glyph rectangle in horizontal writing mode, and the top center in
vertical writing mode (see Section 6.3, »Chinese, Japanese, and Korean Text«, page 79
for details on vertical writing mode). For artificial characters, which do not correspond
to any glyph on the page, the point (x, y) specifies the end point of the most recent
real character. The value of y is subject to the topdown page option.
> The width field specifies the width of a glyph according to the corresponding font
metrics and text output parameters, such as character spacing and horizontal scaling.
Since these parameters control the position of the next glyph, the distance between
the reference points of two adjacent glyphs may be different from width. The
width may be zero for non-spacing characters. On the other hand, the outline may
actually be wider than the glyph’s width value, e.g. for slanted text.
The width is 0 for artificial characters.
> The angle alpha provides the direction of inline text progression, specified as the deviation
from the standard direction. The standard direction is 0˚ for horizontal writing
mode, and -90˚ for vertical writing mode (see below for more details on vertical
6.2 Page and Text Geometry 75