Page 199 Table of Contents Index Page 201
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E



CHAPTER 22. EXTENDED STREAM INPUT
The sheet argument is not evaluated, and must be a symbol that is bound to an input sheet or
stream. If sheet is t, *standard-output* is used. body may have zero or more declarations as
its first forms.

The pointer argument specifies a pointer to track. It defaults to the primary pointer for the
sheet, (stream-primary-pointer sheet).

When the boolean multiple-windows is true, then the pointer will be tracked across multiple
windows, otherwise is will be tracked only in the window corresponding to sheet.

When the boolean transformp is true, then the coordinates supplied to the :pointer-motion
clause will be in the "user" coordinate system rather than in stream coordinates, that is, the
medium's transformation will be applied to the coordinates.

context-type is used to specify the presentation type of presentations that will be "visible" to the
tracking code for purposes of highlighting and for the :presentation, :presentation-button-
press
, and :presentation-button-release clauses. Supplying context-type is only useful when
sheet is an output recording stream. context-type defaults to t, meaning that all presentations
are visible.

When highlight is true, tracking-pointer will highlight applicable presentations as the pointer is
positioned over them. highlight defaults to true when any of the :presentation, :presentation-
button-press
, or :presentation-button-release clauses is supplied, otherwise it defaults to
false.

The body of tracking-pointer consists of a list of clauses. Each clause is of the form
(clause-keyword arglist . clause-body)
and defines a local function to be run upon occurrence of each type of event. The possible values
for clause-keyword and the associated arglist are:


Page 199 Table of Contents Index Page 201
Chapters
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
A, B, C, D, E