[add] canvas-paint example; [refactor] with-current-pen

2 files changed, 15 insertions, 13 deletions

diff --git a/src/canvas-language.lisp b/src/canvas-language.lisp
index 8188e53..b90e22d 100644
--- a/src/canvas-language.lisp
+++ b/src/canvas-language.lisp
@@ -24,17 +24,18 @@
   "Like WITH-CURRENT-PEN, but lets you set the state of the pen
   EXECUTION BODY.  After BODY executes, the state is restored to
   whatever it was before WITH-PEN-STATE was evaluated."
-  `(let ((*current-pen-position* ,(if position nil '*current-pen-position*))
-         (*current-pen-color* ,(if color-supplied-p nil '*current-pen-color*))
-         (*current-pen-width* ,(if width nil '*current-pen-width*)))
-     ,(when position
-        `(move-to ,@position))
-     ,(when color-supplied-p
-        `(canvas-pen-color ,color))
-     ,(when width
-        `(canvas-pen-width ,width))
-     (with-current-pen
-       ,@body)))
+  (with-gensyms (newpos) 
+    `(let ((*current-pen-position* ,(if position nil '*current-pen-position*))
+           (*current-pen-color* ,(if color-supplied-p nil '*current-pen-color*))
+           (*current-pen-width* ,(if width nil '*current-pen-width*)))
+       ,(when position
+          `(let ((,newpos ,position))  (apply 'move-pen-to ,newpos)))
+       ,(when color-supplied-p
+          `(canvas-pen-color ,color))
+       ,(when width
+          `(canvas-pen-width ,width))
+       (with-current-pen
+         ,@body))))
 
 (defmacro with-canvas (canvas &body body)
   "Perform drawing commands in BODY using the value of CANVAS as the
diff --git a/src/interactive/canvas.lisp b/src/interactive/canvas.lisp
index d870ae8..977e3ec 100644
--- a/src/interactive/canvas.lisp
+++ b/src/interactive/canvas.lisp
@@ -3,7 +3,7 @@
 (in-package #:wheelwork)
 
 (defclass/std pixels ()
-  ((pixel-width pixel-height  :std (error "pixel-width and pixel-height are required"))
+  ((pixel-width pixel-height :std (error "pixel-width and pixel-height are required"))
    (data :a :with :doc "Array of RGBA data representing an image of pixel-width X pixel-height")))
 
 (defmethod initialize-instance :after ((pixels pixels) &key)
@@ -23,7 +23,8 @@
 
      I.E. If you are are wanting to manipulate more than one pixel at
      a time, you should get those pixels with USE-CACHED set to NIL."
-    (with-slots (pixel-width pixel-height data) pixels 
+    (let ((pixel-width (pixel-width pixels))
+          (data (pixels-data pixels))) 
       (cond
         ((and use-cached cached-pixel)
          (adjust-array cached-pixel 4