svn: r9447
This commit is contained in:
Matthias Felleisen
parent
65467c8483
commit
538e960133
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@ -2,7 +2,7 @@
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@(require scribble/manual)
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@title[#:tag "draw"]{Draw: draw.*}
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@title[#:tag "Jdraw"]{Draw: draw.*}
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Add
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@verbatim[#:indent 3]{
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@ -18,61 +18,74 @@ import geometry.*;
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+-----------------------------------+
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| abstract World |
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+-----------------------------------+ +---------------------------------------+
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| Canvas theCanvas |------>| Canvas |
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+-----------------------------------+ +---------------------------------------+
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| boolean bigBang(int,int,double) | +---------------------------------------+
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| boolean endOfTime(String) | | boolean show() |
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| World endOfWorld(String) | | boolean close() |
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| | | boolean drawCircle(Posn,int,IColor) |
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| | | boolean drawDisk(Posn,int,IColor) |
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| abstract World onTick() | | boolean drawRect(Posn,int,int,IColor) |
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| abstract World onKeyEvent(String) | | boolean drawLine(Posn,Posn,IColor) |
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| abstract boolean draw() | | boolean drawString(Posn,String) |
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+-----------------------------------+ +---------------------------------------+
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}
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+-----------------------------------+
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| Canvas theCanvas |----+
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+-----------------------------------+ |
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| boolean bigBang(int,int,double) | |
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| boolean endOfTime(String) | |
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| World endOfWorld(String) | |
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| | |
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| | |
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| abstract World onTick() | |
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| abstract World onKeyEvent(String) | |
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| abstract boolean draw() | |
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+-----------------------------------+ |
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v
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+---------------------------------------+
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| Canvas |
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+---------------------------------------+
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+---------------------------------------+
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| boolean show() |
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| boolean close() |
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| boolean drawCircle(Posn,int,IColor) |
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| boolean drawDisk(Posn,int,IColor) |
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| boolean drawRect(Posn,int,int,IColor) |
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| boolean drawLine(Posn,Posn,IColor) |
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| boolean drawString(Posn,String) |
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+---------------------------------------+}
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Methods in these classes may fail due to the unavailability of the physical
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devices, inappropriate uses, etc. In those cases, they fail with an
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exception.
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@section[#:tag "world"]{World}
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@section[#:tag "Jworld"]{World}
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The abstract @scheme[World] class exports the following methods.
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The abstract @tt{World} class exports the following methods.
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@; -----------------------------------------------------------------------------
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bigBang(int width,int height,double speed)
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Initializes the world, associates it with a @scheme[width] x
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@scheme[height] <a href="#canvas">@scheme[Canvas]</a>, displays
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Initializes the world, associates it with a @tt{width} x
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@tt{height} <a href="#canvas">@tt{Canvas}</a>, displays
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this canvas, enables keyevents, and finally starts the clock at a rate of
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one tick per @scheme[speed] seconds. If it succeeds with all of its
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actions, the method produces @scheme[true].
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one tick per @tt{speed} seconds. If it succeeds with all of its
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actions, the method produces @tt{true}.
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@bold{Note}: @scheme[width], @scheme[height] and
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@scheme[speed] must be a positive.
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@bold{Note}: @tt{width}, @tt{height} and
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@tt{speed} must be a positive.
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@; -----------------------------------------------------------------------------
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The canvas in @scheme[World] is called
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The canvas in @tt{World} is called
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@scheme[theCanvas].
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@tt{theCanvas}.
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References to a "canvas" in conjunction with the @scheme[World] class
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References to a "canvas" in conjunction with the @tt{World} class
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denote this default canvas.
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@; -----------------------------------------------------------------------------
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endOfTime()
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Displays the given message, stops the clock and, if it succeeds, produces
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@scheme[true]. After the end of time, events no longer trigger calls
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to @scheme[onTick] or @scheme[onKeyEvent]. The canvas remains visible.
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@tt{true}. After the end of time, events no longer trigger calls
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to @tt{onTick} or @tt{onKeyEvent}. The canvas remains visible.
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@; -----------------------------------------------------------------------------
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endOfWorld(String msg)
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Displays the given message, stops the clock and, if it succeeds, produces the
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last @scheme[World]. After the end of the world, events no longer trigger calls
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to @scheme[onTick] or @scheme[onKeyEvent] (see below). The canvas
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last @tt{World}. After the end of the world, events no longer trigger calls
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to @tt{onTick} or @tt{onKeyEvent} (see below). The canvas
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remains visible.
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@; -----------------------------------------------------------------------------
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@ -82,79 +95,78 @@ A derived concrete class must supply definitions for the following methods:
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onTick()
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Invoked for every tick of the clock. Its purpose is to create a
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@scheme[World] whose differences with @scheme[this] one represent
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@tt{World} whose differences with @tt{this} one represent
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what happened during the amount of time it takes the clock to tick.
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@; -----------------------------------------------------------------------------
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onKeyEvent(String key)
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Invoked for every keyboard event associated with the canvas. Its purposes
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is to create a @scheme[World] whose differences with
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@scheme[this] one represent what happens due to the user's use of the
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is to create a @tt{World} whose differences with
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@tt{this} one represent what happens due to the user's use of the
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keyboard. The latter is represented with the string-valued argument
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@scheme[key].
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@tt{key}.
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@; -----------------------------------------------------------------------------
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draw()
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Invoked <em>after</em> one of the two event handlers has been called. Its
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purpose is to present @scheme[this World ] graphically on its
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canvas. If it succeeds, its result is @scheme[true.]
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purpose is to present @tt{this World} graphically on its
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canvas. If it succeeds, its result is @tt{true}.
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A program may, in principle, start several instances of (subclasses of)
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@scheme[World]. If it does, the event handlers are called in a unpredictable
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@tt{World}. If it does, the event handlers are called in a unpredictable
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order.
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@section[#:tag "canvas"]{Canvas}
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To create an instance of the @scheme[Canvas] class, a program must supply
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two @scheme[int] values: one for the width of the canvas and one for its
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To create an instance of the @tt{Canvas} class, a program must supply
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two @tt{int} values: one for the width of the canvas and one for its
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height. The canvas is a rectangle, whose borders are parallel to the computer
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screen's borders. A program can use the following methods on instances of
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@scheme[Canvas:]
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@tt{Canvas}]
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show()
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Initializes the canvas to a white area, enables the drawing methods, and
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finally displays the canvas. If it succeeds, it produces
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@scheme[true]. Invoking the method a second time without calling
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@scheme[close] before has no effect.
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@tt{true}. Invoking the method a second time without calling
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@tt{close} before has no effect.
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close()
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Hides the canvas and erases the current content. If it succeeds, it
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produces @scheme[true].
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produces @tt{true}.
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Closing the Canvas using the display controls does not fully hide the
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canvas; it is still necessary to invoke @scheme[close] before
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@scheme[show] is re-enabled.
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canvas; it is still necessary to invoke @tt{close} before
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@tt{show} is re-enabled.
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drawCircle(Posn p,int r,IColor c)>
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Draws a circle on @scheme[this Canvas] at @scheme[p] with radius
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@scheme[r] and color @scheme[c]. If it succeeds, it produces
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@scheme[true].
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Draws a circle on @tt{this}Canvas] at @tt{p} with radius
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@tt{r} and color @tt{c}. If it succeeds, it produces
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@tt{true}.
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drawDisk(Posn p,int r,IColor c)
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Draws a disk on @scheme[this Canvas] at @scheme[p] with radius
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@scheme[r] and color @scheme[c]. If it succeeds, it produces
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@scheme[true].
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Draws a disk on @tt{this}Canvas] at @tt{p} with radius
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@tt{r} and color @tt{c}. If it succeeds, it produces
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@tt{true}.
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drawRect(Posn p,int w,int h,IColor c)
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Draws a solid rectangle on @scheme[this Canvas] at @scheme[p] with
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width @scheme[w], height @scheme[h], and color @scheme[c]. The
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Draws a solid rectangle on @tt{this}Canvas] at @tt{p} with
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width @tt{w}, height @tt{h}, and color @tt{c}. The
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rectangle's lines are parallel to the canvas's borders. If it succeeds, it
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produces @scheme[true].
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produces @tt{true}.
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drawLine(Posn p0,Posn p1,IColor c)
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Draws a line on @scheme[this Canvas] from @scheme[p0] to
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@scheme[p1] using color @scheme[c]. If it succeeds, it produces
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@scheme[true].
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Draws a line on @tt{this}Canvas] from @tt{p0} to
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@tt{p1} using color @tt{c}. If it succeeds, it produces
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@tt{true}.
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drawString(Posn p,String s)
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Draws the string @scheme[s] at @scheme[p] on @scheme[this
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Canvas]. If it succeeds, it produces @scheme[true].
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Draws the string @tt{s} at @tt{p} on @tt{this}Canvas]. If it succeeds, it produces @tt{true}.
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@ -1,11 +0,0 @@
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<html>
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<head>
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<title>Teachpacks for How to Design Classes</title>
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</head>
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<body bgcolor="#ffffff" text="#000000" link="#009900" vlink="#007700" alink="#cc0000">
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<h1>Teachpacks for "How to Design Classes"</h1>
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<ul>
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{ LIBLINKS ; libraries should be set before processing this file }</ul>
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{(include "foot.tinc")}
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