[cairo] cairo -> cairo c src backend

Mike Emmel mike.emmel at gmail.com
Fri Sep 22 13:50:30 PDT 2006

On 9/22/06, Behdad Esfahbod <behdad at behdad.org> wrote:
> On Fri, 2006-09-22 at 11:10 -0700, Carl Worth wrote:
> > Yes, I've had this idea at various times. I've never wanted anything
> > that would be very complete, (in the cases I've wanted this, I
> > wouldn't care to get C code to reconstruct the source surfaces, for
> > example), but it would be convenient to be able to grab snippets of
> > code or at least some statistics about what operations are being
> > performed at various times.
> I also had this other idea of reimplementing the paginated stuff using
> the decorator pattern.  Currently paginated is implemented as a single
> decorator, while it shouldn't really be.  The concept of a paginated
> surface is different from the concept of a surface needing whole-page
> analysis.  For example, an animated PNG can be thought of as a paginated
> surface, but the current paginated infrastructure doesn't allow that.
> What we need is decorators for:
>   - paginated
>   - analysis
>   - logging
>   - imagefallback
>   - ...
> the logging decorator will print out all the operations performed on it
> as cairo code to a log file.  It will even have a stack of
> enable/disable states, so you can do things like:
> void draw (cr)
> {
>   cairo_surface_t *surface = cairo_get_target (cr);
>   cairo_logging_surface_save_logging (surface);
>   cairo_logging_surface_set_logging (surface, TRUE);
>   ...drawing code...
>   cairo_logging_surface_restore_logging (surface);
> }
> This way, with non-logging surfaces you get no extra functionality, nor
> errors, but if the context is connected to a surface which is a logging
> decorator, you get the drawing instructions of draw() logged.
> Similarly, you should be able to create a paginated surface out of any
> surface, by just giving the paginated constructor a surface, a show_page
> and a start_page callback, and user data.
> Same for analysis.  It can be used to check whether performed operations
> are supported on the backend of the surface passed in to the
> constructor.
> Then there's the imagefallback decorator.  It uses the metasurface and
> analysis decorator to implement what we are currently doing in PS and
> PDF backends.
> Given these, we will be able to construct the PS backend as a paginated
> decorator for an imagefallback decorator.

Your still missing the meta-gstate concept though correct ?
or more correctly meta-gstate resource-creator watcher to
follow saves/restores transforms patterns etc.
These are not captured ?
> --
> behdad
> http://behdad.org/
> "Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
>         -- Dan Bern, "New American Language"
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