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svn: r10329

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Matthias Felleisen 2008-06-18 02:05:59 +00:00
parent e3fa49cdff
commit 420263b569
1 changed files with 9 additions and 7 deletions
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16
collects/teachpack/htdp/scribblings/world.scrbl
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@ -13,10 +13,8 @@ The teachpack provides two sets of tools. The first allows students to
create and display a series of animated scenes, i.e., a simulation. The create and display a series of animated scenes, i.e., a simulation. The
second one generalizes the first by adding interactive GUI features. second one generalizes the first by adding interactive GUI features.
@declare-exporting[teachpack/htdp/world #:use-sources (teachpack/htdp/image)] @declare-exporting[teachpack/htdp/world #:use-sources (teachpack/htdp/image)]
@section[#:tag "basics"]{Basics} @section[#:tag "basics"]{Basics}
The teachpack assumes working knowledge of the basic image manipulation The teachpack assumes working knowledge of the basic image manipulation
@ -29,10 +27,14 @@ primitives and introduces a special kind of image: a scene.
The teachpack can display only @tech{Scene}s, which are images whose The teachpack can display only @tech{Scene}s, which are images whose
pinholes are at position @scheme[(0,0)]. pinholes are at position @scheme[(0,0)].
@defproc[(empty-scene [width natural-number/c][height natural-number/c]) (unsyntax @tech{Scene})]{Creates a @scheme[width] x @scheme[height] @tech{Scene}.} @defproc[(empty-scene [width natural-number/c]
[height natural-number/c])
(unsyntax @tech{Scene})]
{Creates a @scheme[width] x @scheme[height] @tech{Scene}.}
@defproc[(place-image [img image?] [x number?][y number?][s (unsyntax @tech{Scene})]) (unsyntax @tech{Scene})]{ @defproc[(place-image [img image?] [x number?][y number?]
Creates a scene by placing @scheme[img] at @scheme[(x,y)] into @scheme[s]; [s (unsyntax @tech{Scene})]) (unsyntax @tech{Scene})]
{Creates a scene by placing @scheme[img] at @scheme[(x,y)] into @scheme[s];
@scheme[(x,y)] are comp. graph. coordinates, i.e., they count left and @scheme[(x,y)] are comp. graph. coordinates, i.e., they count left and
down from the upper-left corner.} down from the upper-left corner.}
@ -151,9 +153,9 @@ A @tech{KeyEvent} represents key board events, e.g., keys pressed or
whenever the canvas must be redrawn. The canvas is usually re-drawn after a tick event, a keyboard whenever the canvas must be redrawn. The canvas is usually re-drawn after a tick event, a keyboard
event, or a mouse event has occurred. The generated scene is displayed in the world's canvas.} event, or a mouse event has occurred. The generated scene is displayed in the world's canvas.}
@defproc[(is-end-of-world [last-world? (-> (unsyntax @tech{World}) boolean?)]) true]{ @defproc[(stop-when [last-world? (-> (unsyntax @tech{World}) boolean?)]) true]{
Tell DrScheme to call @scheme[last-world?] whenever the canvas is Tell DrScheme to call @scheme[last-world?] whenever the canvas is
drawn. If this call produces @scheme[true], the clock is stopped; no drawn. If this call produces @scheme[true], the clock is stopped; no more
tick events, @tech{KeyEvent}s, or @tech{MouseEvent}s are forwarded to tick events, @tech{KeyEvent}s, or @tech{MouseEvent}s are forwarded to
the respective handlers. As a result, the canvas isn't updated either.} the respective handlers. As a result, the canvas isn't updated either.}