SECTION 5.2
403
Text State Param eters and Operators
5.2.6 Text Rise
Text rise,
T
rise
, specifies the distance, in unscaled text space units, to move the
baseline up or down from its default location. Positive values of text rise move the
baseline up. Adjustments to the baseline are useful for drawing superscripts or
subscripts. The default location of the baseline can be restored by setting the text
rise to 0. Figure 5.10 illustrates the effect of the text rise. Text rise always applies
to the vertical coordinate in text space, regardless of the writing mode.
(This text is ) Tj
5 Ts
(superscripted) Tj
(This text is ) Tj
–5 Ts
(subscripted) Tj
(This ) Tj
–5 Ts
(text ) Tj
5 Ts
(moves ) Tj
0 Ts
(around) Tj
This text is
superscripted
This text is
subscripted
This
moves
text
around
FIGURE 5.10
Text rise
5.2.7 Text Knockout
The text knockout parameter,
T
k
(PDF 1.4),
is a boolean flag that determines
what text elements are considered elementary objects for purposes of color com-
positing in the transparent imaging model. Unlike other text state parameters,
there is no specific operator for setting this parameter; it can be set only through
the
TK
entry in a graphics state parameter dictionary by using the
gs
operator (see
The text knockout parameter applies only to entire text objects; it may not be set
between the
BT
and
ET
operators delimiting a text object. Its initial value is
true
. If
its value is
false
, each glyph in a text object is treated as a separate elementary ob-
ject; when glyphs overlap, they composite with one another.