[cl-cairo2-devel] patch for image-surface-get-data

[Tamas K Papp]

Hi Johann,

Thanks, I applied your patch.  It is now committed to the repository.

I think that the change to keywords you suggested is very sensible,
and I will do it as soon as I have the time.  I will be travelling
until Tuesday though, so that is the earliest I can do it.  In the
meantime, if you feel you would like to do it and submit a patch, that
would be very welcome.

Best,

Tamas



On Wed, May 28, 2008 at 01:58:55AM +0200, Johann Korndoerfer wrote:
> hello
> 
> included is a diff for extending cl-cairo2 to support extracting pixel
> data (as a 1d array) from image surfaces via image-surface-get-data. it
> also fixes a minor glitch concerning error messages thrown when a symbol
> was not found in a table.
> 
> i also noticed something like
> (cl-cairo2:create-image-surface 'format-argb32 23 42))
> will not work (complaining about not finding the symbol) since the
> symbol cl-user:format-argb32 obviously is not the same as
> cl:cairo2:format-argb32.
> 
> i therefore suggest using keyword symbols for the right halves of the
> tables as well if there is no reason to do otherwise.
> 
> johann

> Index: tables.lisp
> ===================================================================
> --- tables.lisp	(revision 19)
> +++ tables.lisp	(working copy)
> @@ -112,5 +112,5 @@
>  (defun lookup-enum (enum table)
>    (let ((cairo-enum (car (rassoc enum table))))
>      (unless cairo-enum
> -      (error "Could not find ~a in ~a." cairo-enum table))
> +      (error "Could not find ~a in ~a." enum table))
>      cairo-enum))
> Index: surface.lisp
> ===================================================================
> --- surface.lisp	(revision 19)
> +++ surface.lisp	(working copy)
> @@ -113,6 +113,25 @@
>  			       width height)
>     width height t))
>  
> +(defun get-bytes-per-pixel (format)
> +  (case format
> +    (format-argb32 4)
> +    (format-rgb24 3)
> +    (format-a8 1)
> +    (otherwise (error (format nil "unknown format: ~a" format))))) ;todo: how does format-a1 fit in here?
> +
> +(defun image-surface-get-data (surface)
> +  (with-surface (surface pointer)
> +    (let* ((width (image-surface-get-width surface))
> +           (height (image-surface-get-height surface))
> +           (bytes-per-pixel (get-bytes-per-pixel (image-surface-get-format surface)))
> +           (buffer (make-array (* width height bytes-per-pixel) :element-type '(unsigned-byte 8) :fill-pointer 0))
> +           (data (cairo_image_surface_get_data pointer)))
> +      (loop for i from 0 below (* width height bytes-per-pixel) do
> +         (vector-push-extend (cffi:mem-ref data :uint8 i) buffer))
> +      buffer)))
> +
> +
>  (defun image-surface-get-format (surface)
>    (with-surface (surface pointer)
>      (lookup-cairo-enum (cairo_image_surface_get_format pointer) table-format)))
> Index: package.lisp
> ===================================================================
> --- package.lisp	(revision 19)
> +++ package.lisp	(working copy)
> @@ -14,6 +14,7 @@
>     destroy create-ps-surface create-pdf-surface create-svg-surface
>     create-image-surface image-surface-get-format
>     image-surface-get-width image-surface-get-height
> +   image-surface-get-data
>     image-surface-create-from-png surface-write-to-png
>      
>     ;; context

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