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                                                    670
         CHAPTER 8                                                              Interactive Features



         Before a rendition action is executed, the viewer application must make sure that
         the P entry of the screen annotation dictionary references a valid page object and
         that the annotation is present in the page object’s Annots array (see Table 3.27).

         A rendition may play in the rectangle occupied by a screen annotation, even if the
         annotation itself is not visible; for example, if its Hidden or NoView flags (see Ta-
         ble 8.16) are set. If a screen annotation is not visible because its location on the
         page is not being displayed by the viewer, the rendition is not visible. However, it
         may become visible if the view changes, such as by scrolling.


         Transition Actions

         A transition action (PDF 1.5) can be used to control drawing during a sequence of
         actions. As discussed in Section 8.5.1, “Action Dictionaries,” the Next entry in an
         action dictionary can specify a sequence of actions. Viewer applications should
         normally suspend drawing when such a sequence begins and resume drawing
         when it ends. If a transition action is present during a sequence, the viewer should
         render the state of the page viewing area as it exists after completion of the previous
         action and display it using a transition specified in the action dictionary (see Table
         8.65). Once this transition completes, drawing should be suspended again.

                       TABLE 8.65 Additional entries specific to a transition action
KEY     TYPE              VALUE

S       name              (Required) The type of action that this dictionary describes; must be Trans for a
                          transition action.

Trans   dictionary        (Required) The transition to use for the update of the display (see Table 8.13).


         Go-To-3D-View Actions

         A go-to-3D-view action (PDF 1.6) identifies a 3D annotation and specifies a view
         for the annotation to use (see Section 9.5, “3D Artwork”). Table 8.66 shows the
         entries in a go-to-3D-view action dictionary.

                     TABLE 8.66 Additional entries specific to a go-to-3D-view action
KEY     TYPE              VALUE

S       name              (Required) The type of action that this dictionary describes; must be GoTo3DView
                          for a transition action.

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