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added on-release

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svn: r18517
This commit is contained in:
Matthias Felleisen 2010-03-12 03:21:06 +00:00
parent 45da4cb3bc
commit b8a8ca533e
1 changed files with 25 additions and 10 deletions
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35
collects/teachpack/2htdp/scribblings/universe.scrbl
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@ -114,7 +114,7 @@ The step from simulations to interactive programs is relatively
@scheme[_create-image], as a handler for one kind of event: clock ticks. In @scheme[_create-image], as a handler for one kind of event: clock ticks. In
addition to clock ticks, @tech{world} programs can also deal with two addition to clock ticks, @tech{world} programs can also deal with two
other kinds of events: keyboard events and mouse events. A keyboard event other kinds of events: keyboard events and mouse events. A keyboard event
is triggered when a computer user presses or releases a key on the is triggered when a computer user presses a key on the
keyboard. Similarly, a mouse event is the movement of the mouse, a click keyboard. Similarly, a mouse event is the movement of the mouse, a click
on a mouse button, the crossing of a boundary by a mouse movement, etc. on a mouse button, the crossing of a boundary by a mouse movement, etc.
@ -154,13 +154,14 @@ The design of a world program demands that you come up with a data
@defform/subs[#:id big-bang @defform/subs[#:id big-bang
#:literals #:literals
(on-tick on-draw on-key on-mouse on-receive stop-when (on-tick on-draw on-key on-release on-mouse on-receive stop-when
check-with register record? state name) check-with register record? state name)
(big-bang state-expr clause ...) (big-bang state-expr clause ...)
([clause ([clause
(on-tick tick-expr) (on-tick tick-expr)
(on-tick tick-expr rate-expr) (on-tick tick-expr rate-expr)
(on-key key-expr) (on-key key-expr)
(on-release release-expr)
(on-mouse key-expr) (on-mouse key-expr)
(on-draw draw-expr) (on-draw draw-expr)
(on-draw draw-expr width-expr height-expr) (on-draw draw-expr width-expr height-expr)
@ -209,8 +210,7 @@ tell DrScheme to call the @scheme[tick-expr] function on the current
world every time the clock ticks. The result of the call becomes the world every time the clock ticks. The result of the call becomes the
current world. The clock ticks at the rate of @scheme[rate-expr].}} current world. The clock ticks at the rate of @scheme[rate-expr].}}
@item{A @tech{KeyEvent} represents key board events, e.g., keys pressed or @item{A @tech{KeyEvent} represents key board events.
released.
@deftech{KeyEvent} : @scheme[string?] @deftech{KeyEvent} : @scheme[string?]
@ -238,7 +238,6 @@ Second, some keys have multiple-character string representations. Strings
@item{@scheme["right"] is the right arrow;} @item{@scheme["right"] is the right arrow;}
@item{@scheme["up"] is the up arrow;} @item{@scheme["up"] is the up arrow;}
@item{@scheme["down"] is the down arrow;} @item{@scheme["down"] is the down arrow;}
@item{@scheme["release"] is the event of releasing a key;}
@item{@scheme["start"]} @item{@scheme["start"]}
@item{@scheme["cancel"]} @item{@scheme["cancel"]}
@item{@scheme["clear"]} @item{@scheme["clear"]}
@ -311,10 +310,10 @@ Second, some keys have multiple-character string representations. Strings
@defproc[(key=? [x key-event?][y key-event?]) boolean?]{ @defproc[(key=? [x key-event?][y key-event?]) boolean?]{
compares two @tech{KeyEvent} for equality} compares two @tech{KeyEvent} for equality}
@defform[(on-key change-expr) @defform[(on-key key-expr)
#:contracts #:contracts
([change-expr (-> (unsyntax @tech{WorldState}) key-event? (unsyntax @tech{WorldState}))])]{ ([key-expr (-> (unsyntax @tech{WorldState}) key-event? (unsyntax @tech{WorldState}))])]{
tell DrScheme to call @scheme[change-expr] function on the current world and a tell DrScheme to call the @scheme[key-expr] function on the current world and a
@tech{KeyEvent} for every keystroke the user of the computer makes. The result @tech{KeyEvent} for every keystroke the user of the computer makes. The result
of the call becomes the current world. of the call becomes the current world.
@ -332,6 +331,16 @@ Second, some keys have multiple-character string representations. Strings
} }
The omitted, auxiliary function @emph{world-go} is supposed to consume a The omitted, auxiliary function @emph{world-go} is supposed to consume a
world and a number and produces a world. world and a number and produces a world.
@defform[(on-release release-expr)
#:contracts
([release-expr (-> (unsyntax @tech{WorldState}) key-event? (unsyntax @tech{WorldState}))])]{
tell DrScheme to call the @scheme[release-expr] function on the current world and a
@tech{KeyEvent} for every release event on the keyboard. A release event
occurs when a user presses the key and then releases it. The second argument
indicates which key has been released. The result of the function call
becomes the current world.
}
} }
@item{ A @tech{MouseEvent} represents mouse events, e.g., mouse movements @item{ A @tech{MouseEvent} represents mouse events, e.g., mouse movements
@ -668,9 +677,15 @@ As mentioned, all event handlers may return @tech{WorldState}s or
} }
@defform/none[#:literals (on-key) @defform/none[#:literals (on-key)
(on-key change-expr) (on-key key-expr)
#:contracts #:contracts
([change-expr (-> (unsyntax @tech{WorldState}) key-event? (or/c (unsyntax @tech{WorldState}) package?))])]{ ([key-expr (-> (unsyntax @tech{WorldState}) key-event? (or/c (unsyntax @tech{WorldState}) package?))])]{
}
@defform/none[#:literals (on-release)
(on-release release-expr)
#:contracts
([release-expr (-> (unsyntax @tech{WorldState}) key-event? (or/c (unsyntax @tech{WorldState}) package?))])]{
} }
@defform/none[#:literals (on-mouse) @defform/none[#:literals (on-mouse)