adding view-width and view-height methods

examples/drag-and-drop/drag-and-drop-1.rkt

@@ -11,8 +11,6 @@
 ;; The world consists of a set of boxes.
 ;;
 ;; A box has an id and a position.
-
-(define-struct world (boxes))
 (define-struct box (id x y))
 
 

examples/drag-and-drop/drag-and-drop-2.rkt

@@ -8,11 +8,13 @@
 
 ;; A small drag-and-drop example using the web-world library.
 ;;
-;; The world consists of a set of boxes.
+;; The world consists of a set of boxes.  It also has a reference
-;;
+;; to the currently dragged box, if one is being dragged.
-;; A box has an id and a position.
+(define-struct world (boxes  ;; (listof box)
+                      dragged ;; (U box #f)
+                      ))
 
-(define-struct world (boxes))
+;; A box has an id and a position.
 (define-struct box (id x y))
 
 
@@ -21,10 +23,11 @@
 ;; Given a world, creates a new world within the boundaries of the playground.
 (define (add-fresh-box w v)
   (define-values (max-width max-height) (width-and-height "playground"))
-  (define new-world (cons (make-box (fresh-id)
+  (define new-world (make-world (cons (make-box (fresh-id)
-                                    (random max-width)
+                                                (random max-width)
-                                    (random max-height))
+                                                (random max-height))
-                          w))
+                                      (world-boxes w))
+                                (world-dragged w)))
   new-world)
 
 
@@ -49,14 +52,24 @@
                                                                    (box-y a-box))))
                                                  "box")))]))
          (view-focus v "playground")
-         w))
+         (world-boxes w)))
+
+
+;; When the mouse is down, we see if the event intersects any of our boxes.
+(define (mousedown w v evt)
+  ...)
+
+
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define the-view (view-bind-many view.html
-                                 ["add" "click" add-fresh-box]))
+                                 ["add" "click" add-fresh-box]
+                                 ["playground" "mousedown" mousedown]
+                                 ["playground" "mousemove" mousemove]
+                                 ["playground" "mouseup" mouseup]))
   
-(big-bang (list)
+(big-bang (make-world (list) #f)
           (initial-view the-view)
           (to-draw draw))
           

scribblings/manual.scrbl

@@ -1043,6 +1043,14 @@ Update the attribute @racket[name] with the value @racket[value] at the focus.
 Remove the attribute @racket[name] at the focus.
 }
 
+@defproc[(view-width [v view]) number]{
+Get the width at the focus.
+}
+
+@defproc[(view-height [v view]) number]{
+Get the height at the focus.
+}
+
 @defproc[(view-css [v view] [name String]) view]{
 Get the css value @racket[name] at the focus.
 }

web-world/impl.rkt

@@ -71,6 +71,9 @@
 
                     view-css
                     update-view-css
+
+                    view-width
+                    view-height
                     
                     view-id
                     

web-world/js-impl.js

@@ -307,6 +307,14 @@
         return $(this.getCursor().node[0]).css(name);
     };
 
+    MockView.prototype.getWidth = function(name) {        
+        return $(this.getCursor().node[0]).width();
+    };
+
+    MockView.prototype.getHeight = function(name) {        
+        return $(this.getCursor().node[0]).height();
+    };
+
 
     MockView.prototype.updateCss = function(name, value) {
         return this.act(
@@ -2018,6 +2026,20 @@
             return view.getCss(name);
         });
 
+    EXPORTS['view-width'] = makePrimitiveProcedure(
+        'view-width',
+        1,
+        function(MACHINE) {
+            var view = checkMockViewOnElement(MACHINE, 'view-width', 0);
+            return view.getWidth();
+        });
+    EXPORTS['view-height'] = makePrimitiveProcedure(
+        'view-height',
+        1,
+        function(MACHINE) {
+            var view = checkMockViewOnElement(MACHINE, 'view-height', 0);
+            return view.getHeight();
+        });
 
     EXPORTS['update-view-css'] = makePrimitiveProcedure(
         'update-view-css',

web-world/racket-impl.rkt

@@ -20,6 +20,7 @@
          view-text update-view-text
          view-attr view-has-attr? update-view-attr remove-view-attr
          view-css update-view-css
+         view-width view-height
          view-id
 
          view-bind
@@ -163,6 +164,12 @@
 (define (view-css v attr-name)
   (error 'view-css "Please run in JavaScript context."))
 
+(define (view-width v)
+  (error 'view-width "Please run in JavaScript context."))
+
+(define (view-height v)
+  (error 'view-height "Please run in JavaScript context."))
+
 (define (update-view-css v attr-name value)
   (error 'update-view-css "Please run in JavaScript context."))