81 lines
3.6 KiB
Racket
81 lines
3.6 KiB
Racket
#lang scribble/manual
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@(require (for-label scribble/eval scriblib/gui-eval))
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@title[#:tag "gui-eval"]{Writing Examples with Pict Results}
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@defmodule[scriblib/gui-eval]{The
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@schememodname[scriblib/gui-eval] library support example
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evaluations with results that are @schememodname[slideshow] picts.}
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The trick is that @schememodname[racket/gui] is not generally
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available when rendering documentation, because it requires a GUI
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context. The picture output is rendered to an image file when the
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@envvar{MREVAL} environment variable is set, so run the enclosing
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document once with the environment varibale to generate the
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images. Future runs (with the environment variable unset) use the
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generated image.
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@deftogether[(
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@defform*[((gui-interaction datum ...)
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(gui-interaction
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))
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]
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@defform*[((gui-interaction-eval datum ...)
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(gui-interaction-eval
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ... ))]
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@defform*[((gui-interaction-eval-show datum ...)
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(gui-interaction-eval-show
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))]
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@defform*[((gui-schemeblock+eval datum ...)
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(gui-schemeblock+eval
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))]
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@defform*[((gui-schememod+eval datum ...)
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(gui-schememod+eval
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))]
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@defform*[((gui-def+int datum ...)
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(gui-def+int
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))]
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@defform*[((gui-defs+int datum ...)
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(gui-defs+int
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#:eval+opts the-eval get-predicate? get-render
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get-get-width get-get-height
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datum ...))]
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)]{
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The first option of each of the above is
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like @scheme[interaction], etc., but actually evaluating the forms
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only when the @envvar{MREVAL} environment variable is set, and then in
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an evaluator that is initialized with @schememodname[racket/gui/base]
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and @schememodname[slideshow].
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The second option of each allows you to specify your own evaluator via
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the @scheme[the-eval] argument and then to specify four thunks that
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return functions for finding and rendering graphical objects:
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@itemize[
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@item{@scheme[get-predicate? : (-> (-> any/c boolean?))]
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Determines if a value is a graphical object (and thus handled by the other operations)}
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@item{@scheme[get-render : (-> (-> any/c (is-a?/c dc<%>) number? number? void?))]
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Draws a graphical object (only called if the predicate returned @scheme[#t]; the first
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argument will be the value for which the predicate holds).}
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@item{@scheme[get-get-width : (-> (-> any/c number?))]
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Gets the width of a graphical object (only called if the predicate returned @scheme[#t]; the first
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argument will be the value for which the predicate holds).}
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@item{@scheme[get-get-height : (-> (-> any/c number?))]
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Gets the height of a graphical object (only called if the predicate returned @scheme[#t]; the first
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argument will be the value for which the predicate holds).}
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]
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}
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