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Re: Drawing Cursor or Cursor to PICT
- To: firstname.lastname@example.org
- Subject: Re: Drawing Cursor or Cursor to PICT
- From: email@example.com (Bill St. Clair)
- Date: Wed, 13 May 1992 14:41:05 -0500
- Cc: gb, info-mcl
>Thanks for the hack and the advice. I can't seem to find any documentation
>for with-macptrs. Is that the same as with-pointers? If so, I don't
>understand the usefulness of it here. ccl::%getport is not likely to
>return a handle, is it?
WITH-MACPTRS is basically the same as LET and DYNAMIC-EXTENT, but
it's a little more likely to avoid consing a macptr. E.g. the
following conses a macptr:
(let ((foo (#_GetCursor #$IBeamCursor)))
(declare (dynamic-extent foo))
but this code does not.
(with-macptrs ((foo (#_GetCursor #$IBeamCursor)))
WITH-POINTERS dereferences and locks any handles you pass it.
Hence, WITH-MACPTRS is a much lower-level macro.
That the former conses a mactpr may qualify as a compiler bug, but
since the latter does not, it's no killer.
>I'm all done with the tool-pallette code, and will put it in the drop-box
>(or post it if there is no drop-box) as soon as I figure this out.
By drop-box do you mean the anonymous FTP server at cambridge.apple.com?
>Oh yeah, is there any way to use #_GetPort rather than the undocumented
>%getport? I tried it with a straightforward substitution, and it didn't
>work. But I thought you might know a way to do it.
>BTW, is it a bug that *arrow-cursor* is a pointer rather than a handle? I
>don't care much, of course, since it's not too hard to handle [pun
>intended] both cases.
*arrow-cursor* is intentionally a pointer. The following modification
of my initial hack solves the problems you mention. All the %setf-macptr's
are to avoid heap consing the cursor-pointer value.
; Drawing a cursor to a grafport.
; Does not handle the mask.
; May fail if the cursor resource is purgeable.
; If cursor is a fixnum, calls #_GetCursor on it.
; If cursor is a handle, dereferences it.
; Otherwise, cursor should be a pointer to a cursor record.
(defun draw-cursor (cursor h &optional v)
(let ((p (make-point h v))
(declare (dynamic-extent cursor-pointer))
(cond ((fixnump cursor)
(with-macptrs ((handle (#_GetCursor cursor)))
(when (%null-ptr-p handle)
(error "~s does not specify a valid cursor" cursor))
(%setf-macptr cursor-pointer (%get-ptr handle))))
(%setf-macptr cursor-pointer (%get-ptr cursor)))
(t (%setf-macptr cursor-pointer cursor)))
(rlet ((srcrect :rect :topleft #@(0 0) :botRight #@(16 16))
(dstrect :rect :topleft p :botright (add-points p #@(16 16)))
(rlet ((port-var :pointer))
(rref (%get-ptr port-var) :grafport.portbits)
(defparameter *w* (make-instance 'window))
(defun draw-cursors (&optional (cursors
(let ((point #@(10 50)))
(dolist (cursor cursors)
(draw-cursor cursor point)
(setq point (add-points point #@(24 0)))))))