[Sugar-devel] TA cairo conversion

[C. Scott Ananian]

I've been pushing my work to
 http://git.sugarlabs.org/~walter/turtleart/walters-gtk3/commits/cscotts-gtk3

I'll rebase to the latest cairo bits.  (It might be best to continue
working with HEAD of my branch, since it runs fine on gtk2 and will
minimize unnecessary patch conflicts.)  It's also a little confusing
to have so many clones: walters-cairo, walters-gtk3, cscott-gtk3, etc.
 Can we pick one clone and stick with it, even if we're going to work
on separate branches?

Gtk2 operation on my branch is unmodified, although the code uses Gtk3
"style" throughout, for future-proofing.  The GTK3 version just needs
some more incremental fixes; at the moment it's failing trying to
create a CairoContext from a canvas---which I think should just be a
no-op, more or less.  Just a matter of getting enough time to work
through the fixes, help welcome.
  --scott

On Sat, Nov 5, 2011 at 9:15 AM, Benjamin Berg <benzea at sugarlabs.org> wrote:
> Hello,
>
> On Sat, 2011-11-05 at 08:56 -0400, Walter Bender wrote:
>> I pushed a few more patches last night [1]. I have just two blockers
>> right now to releasing the Cairo version:
>>
>> (1) I cannot seem to figure out how to convert my surface to a pixbuf
>> or png for saving to a file;
>>         surface = canvas.canvas.get_target()  # get the surface used
>> by the canvas
>>         surface.cairo_surface_write_to_png(file_name)  <--- fails
>> because XlibSurface doesn't have a cairo_surface_write_to_png
>> attribute
>
> What you can do is the following:
>  1. x_surface = canvas.canvas.get_target()
>  2. Create an image surface:
>    img_surface = cairo.ImageSurface(...)
>  3. Create a context:
>    cr = cairo.Context(img_surface)
>  4. cr.set_source_surface(x_surface)
>  5. cr.paint()
>  6. img_surface.write_to_png(file_name)
>
> This way you can download the image data from the X server, and store it
> inside the applications memory. After this it can be written out to a
> file.
>
>> (2) I cannot seem to create the proper surface from a Pixbuf to use in
>> non-interactive mode in replacement of the canvas surface. I have
>> unsuccessfully tried to create a pixbuf and use it to source a cairo
>> context.
>
> The pixel format that cairo uses, and the one that Gdk.Pixbuf uses is
> differs.  If I understand correctly, what you want to do is to create an
> cairo.ImageSurface instead of the create_similar call.
>
>> The only non-blockers are:
>> (1) I am struggling with the erratic behavior of rotate on bitmaps. It
>> is disabled at the moment.
>> (2) There must be some way to cache the surfaces used by the sprites
>> instead of re-rendering them from pixbufs each time, but using
>> get_target() gives X errors.
>
> Hm, I can't say anything about these of the top of my head.
>
> Benjamin
>
>



-- 
      ( http://cscott.net )