00ef7da640
Also, improve docs to clarify how the recorded settings interact with the target DC's settings.
50 lines
2.0 KiB
Racket
50 lines
2.0 KiB
Racket
#lang scribble/doc
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@(require "common.rkt")
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@defclass/title[record-dc% object% (dc<%>)]{
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A @racket[record-dc%] object records drawing actions for replay into
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another drawing context. The recorded drawing operations can be
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extracted as a procedure via @method[record-dc%
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get-recorded-procedure], or the actions can be extracted as a datum
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(that can be printed with @racket[write] and recreated with
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@racket[read]) via @method[record-dc% get-recorded-datum].
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When drawing recorded actions, the target drawing context's pen,
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brush, font, text, background, text background, and text foreground do
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not affect the recorded actions. The target drawing context's
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transformation, alpha, and clipping region compose with settings in
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the recorded actions (so that, for example, a recorded action to set
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the clipping region actually intersects the region with the drawing
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context's clipping region at the time that the recorded commands are
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replayed). After recoded commands are replayed, all settings in the
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target drawing context, such as its clipping region or current font,
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are as before the replay.
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@defconstructor[([width (>=/c 0) 640]
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[height (>=/c 0) 480])]{
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Creates a new recording DC. The optional @racket[width] and
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@racket[height] arguments determine the result of @method[dc<%>
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get-size] on the recording DC; the @racket[width] and
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@racket[height] arguments do not clip drawing.}
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@defmethod[(get-recorded-datum) any/c]{
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Extracts a recorded drawing to a value that can be printed with
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@racket[write] and re-read with @racket[read]. Use
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@racket[recorded-datum->procedure] to convert the datum to a drawing
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procedure.}
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@defmethod[(get-recorded-procedure) ((is-a?/c dc<%>) . -> . void?)]{
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Extracts a recorded drawing to a procedure that can be applied to
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another DC to replay the drawing commands to the given DC.
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The @method[record-dc% get-recorded-procedure] method can be more
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efficient than composing @method[record-dc% get-recorded-datum] and
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@racket[recorded-datum->procedure].}}
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