fixed bug and specs of draw/idraw Canvases in htdch

svn: r3865

collects/graphics/graphics-posn-less-unit.ss

@@ -251,6 +251,7 @@
         [stop-tick 
          (lambda ()
 	   (send the-time stop)
+	   (set! on-char-proc #f)
 	   the-world)]
         [init-world (lambda (w) (set! the-world w))])
       ;; --- end timing stuff

collects/htdch/draw/Canvas.java

@@ -18,8 +18,22 @@ public class Canvas {
     // I need to figure out how to accomplish these two things, especially stop,
     // directly at the Scheme level w/o going thru the Java layer.
      
-  public native boolean show();
-  public native boolean close();
+    private boolean showing = false; 
+    public boolean show() { 
+	if (!showing) {
+	    xshow();
+	    showing = true; 
+	}
+	return true; 
+    }
+    public boolean close() { 
+	xclose(); 
+	showing = false; 
+	return true; 
+    }
+	    
+  public native boolean xshow();
+  public native boolean xclose();
   public native boolean drawCircle(Posn p, int r, Color c);
   public native boolean drawDisk(Posn p, int r, Color c);
   public native boolean drawRect(Posn p, int width, int height, Color c);

collects/htdch/draw/support.scm

@@ -16,8 +16,8 @@
      bigBangO-double-native))
   
   (define-signature canvas-native^
-    (show-native
-     close-native
+    (xshow-native
+     xclose-native
      stop-native
      copy-native
      drawCircle-geometry.Posn-int-colors.Color-native
@@ -88,7 +88,7 @@
 			       (lower (cdr s))))))))
 	  (list->string (lower (string->list s)))))
   
-      (define (show-native this accs gets privates)
+      (define (xshow-native this accs gets privates)
 	;; Kathy: it looks like I am working around a bug here. 
 	;; I really wanted to write ([hash-table-get privates 'width] this)
 	;; but that didn't work at all. 'width is not a key for privates, 
@@ -100,8 +100,9 @@
 	(start-and-export x y privates)
 	void-or-true)
   
-      (define (close-native this accs gets privates)
-	(wrap-start-check ([hash-table-get privates '%stop])))
+      (define (xclose-native this accs gets privates)
+	(wrap-start-check ([hash-table-get privates '%stop]))
+	void-or-true)
   
       (define (stop-native this accs gets privates)
 	(wrap-start-check ([hash-table-get privates '%end-of-time])))

collects/htdch/idraw/Canvas.java

@@ -18,8 +18,23 @@ public class Canvas {
     // MF: I need to figure out how to accomplish these two things, especially
     //     stop, directly at the Scheme level w/o going thru the Java layer.
      
-  public native void show();
-  public native void close();
+     
+    private boolean showing = false; 
+    public void show() { 
+	if (!showing) {
+	    xshow();
+	    showing = true; 
+	}
+	return ; 
+    }
+    public void close() { 
+	xclose(); 
+	showing = false; 
+	return ; 
+    }
+	    
+  public native void xshow();
+  public native void xclose();
   public native void drawCircle(Posn p, int r, Color c);
   public native void drawDisk(Posn p, int r, Color c);
   public native void drawRect(Posn p, int width, int height, Color c);

collects/htdp/big-draw.ss

@@ -209,14 +209,17 @@
       (setter vp* pm* %clear-string (make-%string 'clear-string (clear-string vp*))) 
       ;; --- 
       (set! %end-of-time
+	(let () #;([vp* vp*][pm* pm*])
             (lambda () 
               [(stop-tick vp*)]
               [(stop-tick pm*)] 
-              #t))
+              #t)))
       (hash-table-put! h '%end-of-time %end-of-time)
       ;; ---
       (set! %stop
-            (let ([a (lambda () (close-viewport @vp) (close-viewport @pm))])
+            (let* ([vp* vp*]
+		   [pm* pm*]
+		   [a (lambda () (close-viewport vp*) (close-viewport pm*))])
               (lambda ()
                 [(stop-tick vp*)]
                 [(stop-tick pm*)]

collects/teachpack/htdc/Docs/draw.thtml

@@ -40,18 +40,27 @@ this canvas, 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>. 
 
-<p>A <code>World</code> is associated with one default <code>Canvas</code>,
-called <code>theCanvas</code>. If a <code>World</code> needs additional
-canvases for its graphical presentation, its concrete subclasses must add
-those.</p>
+<p><strong>Note:</strong> <code>width</code> and <code>height</code> must be
+  positive <code>int</code>s, <code>speed</code> must be a positive
+  <code>double</code>.
+</p>
+
+<p>The canvas in <code>World</code> is called
+  <code>theCanvas</code>. References to a "canvas" in conjunction with the
+  <code>World</code> class denote this default canvas.
+</p>
 </li>
 
 <li><code>endOfTime</code>, stops the clock and, if it succeeds, produces
-<code>true</code>. 
+ <code>true</code>. After the end of time, events no longer trigger calls
+ to <code>onTick</code> or <code>onKeyEvent</code> (see below). The canvas
+ remains visible. 
 </li>
 
 <li><code>endOfWorld</code>, stops the clock and, if it succeeds, produces the
-last <code>World</code>. 
+ last <code>World</code>. After the end of the world,  events no longer trigger calls
+ to <code>onTick</code> or <code>onKeyEvent</code> (see below). The canvas
+ remains visible. 
 </li>
 </ul>
 The methods may fail due to the unavailability of the physical devices,
@@ -65,11 +74,11 @@ purpose is to create a <code>World</code> whose differences with
 the clock to tick. 
 </li>
 
-<li><code>onKeyEvent(key)</code>, which is invoked for every keyboard event. Its
-purposes is to create a <code>World</code> whose differences with
-<code>this</code> one represent what happens due to the user's use of the
-keyboard. The latter is represented with the string-valued argument
-<code>key</code>.  
+<li><code>onKeyEvent(key)</code>, which is invoked for every keyboard event
+  associated with the canvas. Its purposes is to create a
+  <code>World</code> whose differences with <code>this</code> one represent
+  what happens due to the user's use of the keyboard. The latter is
+  represented with the string-valued argument <code>key</code>.
 </li>
 
 <li><code>draw()</code>, which is invoked <em>after</em> one of the two event
@@ -80,6 +89,8 @@ graphically on its canvas. If it succeeds, its result is <code>true.</code>
 <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>
 </ul>
 A program may, in principle, start several instances of (subclasses of)
@@ -94,10 +105,14 @@ 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>.</li>
+  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>.</li>
+If it succeeds, it produces <code>true</code>. Invoking <code>show</code>
+  again, displays an empty canvas of the same size. 
+</li>
 
 <li><code>drawCircle(p,r,c)</code>, which draws a circle on <code>this
 Canvas</code> at <code>p</code> with radius <code>r</code> and color