SECTION 8.4
613
Anno ta tions
The annotation may be further scaled and rotated if either the NoZoom or
NoRotate flag is set (see Section 8.4.2, “Annotation Flags”). Any transformation
applied to the annotation as a whole is also applied to the appearance within it.
In PDF 1.4, an annotation appearance can include transparency. If the appear-
ance’s stream dictionary does not contain a
Group
entry, it is treated as a non-iso-
lated, non-knockout transparency group. Otherwise, the isolated and knockout
values specified in the group dictionary (see Section 7.5.5, “Transparency Group
The transparency group is composited with a backdrop consisting of the page
content along with any previously painted annotations, using a blend mode of
Normal
, an alpha constant of 1.0, and a soft mask of
None
. (See implementation
Note:
If a transparent annotation appearance is painted over an annotation that is
drawn without using an appearance stream, the effect is implementation-depen-
dent. This is because such annotations are sometimes drawn by means that do not
conform to the Adobe imaging model. Also, the effect of highlighting a transparent
annotation appearance is implementation-dependent.
An annotation can define as many as three separate appearances:
•
The
normal appearance
is used when the annotation is not interacting with the
user. This appearance is also used for printing the annotation.
•
The
rollover appearance
is used when the user moves the cursor into the anno-
tation’s active area without pressing the mouse button.
•
The
down appearance
is used when the mouse button is pressed or held down
within the annotation’s active area.
Note:
As used here, the term
mouse
denotes a generic pointing device that controls
the location of a cursor on the screen and has at least one button that can be pressed,
held down, and released. See Section 8.5.2, “Trigger Events,” for further discussion.
The normal, rollover, and down appearances are defined in an
appearance
dictionary,
which in turn is the value of the
AP
entry in the annotation dictionary
(see Table 8.15 on page 606). Table 8.19 shows the contents of the appearance dic-
tionary.