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indexed world

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svn: r1600
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Matthias Felleisen 2005-12-12 21:10:48 +00:00
parent 4d76550b9f
commit b4a2f0570e
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18
teachpack/htdp/Docs/world.thtml
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@ -4,18 +4,18 @@
<p>The teachpack provides two kinds of functions. The first four allow
students to simulate a small world of animated drawings and games:
<menu>
<li><code>big-bang : Number Number Number World -> true</code><br>
<li><code>{(idx big-bang)} : Number Number Number World -> true</code><br>
<code>(big-bang width height n w)</code>
creates and shows a width x height canvas,
starts the clock,
makes it tick every n seconds,
and makes w the first world
<li><code>on-tick-event : (World -> World) -> true</code><br>
<li><code>{(idx on-tick-event)} : (World -> World) -> true</code><br>
<code>(on-tick-event tock)</code> means that DrScheme must call <code>tock</code>
on the current world every time the clock ticks; it uses the result as the next world
<li><code>on-key-event : (World KeyEvent -> World) -> true</code><br>
<li><code>{(idx on-key-event)} : (World KeyEvent -> World) -> true</code><br>
<code>(on-key-event change)</code> means that DrScheme must call
<code>change</code> on the current world and a (representation of the)
keyevent for every keystroke the programmer (user of the computer) makes; it uses
@ -33,32 +33,32 @@ students to simulate a small world of animated drawings and games:
or the events of releasing a key on the keypad.
</pre>
<li><code>on-redraw : (World -> Image) -> true</code><br>
<li><code>{(idx on-redraw)} : (World -> Image) -> true</code><br>
<code>(on-tick-event world->image)</code> means that DrScheme
calls <code>world->image</code> whenever the canvas must be redrawn; the
result is displayed in the teachpack's canvas
<li><code>end-of-time String u Symbol : -> World</code><br> When DrScheme
<li><code>{(idx end-of-time)} : String u Symbol -> World</code><br> When DrScheme
evaluates <code>(end-of-time)</code>, it stops the clock and displays the
given string or symbol; no further tick events, key events, or redraw events
take place until the world is created again. </menu></p>
<p>The rest are functions for creating scenes:
<menu>
<li><code>nw:rectangle : Number Number Mode Color -> Image</code><br>
<li><code>{(idx nw:rectangle)} : Number Number Mode Color -> Image</code><br>
<code>(nw:rectangle width height mode color)</code>
creates a width x height rectangle, solid or outlined,
with its anchor in the NW corner
<li><code>empty-scene : Number Number -> Scene</code><br>
<li><code>{(idx empty-scene)} : Number Number -> Scene</code><br>
<code>(empty-scene width height)</code>
creates a width x height "scene" (frame with origin in NW)
<li><code>place-image : Image Number Number Scence -> Scene</code><br>
<li><code>{(idx place-image)} : Image Number Number Scence -> Scene</code><br>
<code>(place-image image x y scene)</code>
places image at (x,y) into scene; (x,y) are comp. graph. coordinates
<li><code>run-movie : (Listof Image) -> true </code><br>
<li><code>{(idx run-movie)} : (Listof Image) -> true </code><br>
<code>(run-movie loi)</code>
shows the list of images in loi, time-delayed
</menu></p>