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documentation bug in draw

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svn: r3894
This commit is contained in:
Matthias Felleisen 2006-07-29 15:47:54 +00:00
parent 84021a7e40
commit 581100edbe
1 changed files with 16 additions and 12 deletions
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26
collects/teachpack/htdc/Docs/draw.thtml
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@ -36,7 +36,7 @@ import geometry.*;
<li><code>bigBang(width,height,speed)</code>, which initializes the world,
associates it with a <code>width</code> x <code>height</code> <a
href="#canvas"><code>Canvas</code></a>, displays
this canvas, and finally starts the clock at a rate of one tick per
this canvas, enables keyevents, and finally starts the clock at a rate of one tick per
<code>speed</code> seconds. If it succeeds with all of its actions, the method
produces <code>true</code>.
@ -86,11 +86,11 @@ handlers has been called. Its purpose is to present <code>this World </code>
graphically on its canvas. If it succeeds, its result is <code>true.</code>
</li>
<li><code>erase()</code>, which is invoked <em>after</em> one of the two event
handlers has been called. Its purpose is to erase <code>this World</code>'s
canvas, as much as needed. If it succeeds, its result is <code>true.</code>
Simple erase methods just draw a white rectangle of appropriate width and
height located at the origin.
<li><code>erase()</code>, which is invoked <em>before</em> one of the two event
handlers has been called. Its purpose is to erase <code>this World</code>'s
canvas, as much as needed. If it succeeds, its result is <code>true.</code>
Simple erase methods just draw a white rectangle of appropriate width and
height located at the origin.
</li>
</ul>
A program may, in principle, start several instances of (subclasses of)
@ -104,14 +104,18 @@ height. The canvas is a rectangle, whose borders are parallel to the computer
screen's borders. A program can use the following methods on instances of
<code>Canvas:</code>
<ul>
<li><code>show()</code>, which displays the canvas.
If it succeeds, it produces <code>true</code>. Invoking the method a second
<li><code>show()</code>, which initializes the canvas to a white area,
enables the drawing methods, and finally displays the canvas. If it
succeeds, it produces <code>true</code>. Invoking the method a second
time without calling <code>close</code> before has no effect.
</li>
<li><code>close()</code>, which destroys the canvas.
If it succeeds, it produces <code>true</code>. Invoking <code>show</code>
again, displays an empty canvas of the same size.
<li><code>close()</code>, which hides the canvas. If it succeeds, it produces <code>true</code>.
<p>Closing the Canvas using the display controls does not fully hide the
canvas; it is still necessary to invoke <code>close</code> before
<code>show</code> is re-enabled.</p>
</li>
<li><code>drawCircle(p,r,c)</code>, which draws a circle on <code>this