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SECTION 8.4                                                               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
XObjects”) are used.

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 87 in Appendix H.)

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.

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