Re: New libart/freetype-based backend

[Adam Fedor]

Alexander Malmberg wrote:
> Disadvantages are:
> - It's slower than xgps (but still fast enough to use), and uses more
> memory (double backing store: both the gsc/ stuff and the internal
> buffer).

Well sorry to change the graphics interface on you, but I just commited 
change that does this...

I though it was odd to have to use both -contextDevice: and 
DPSsetgcdrawable:::: to setup the graphics context with the correct 
drawable, so I combined these both into:

- (void) GSSetDevice: (void*)device : (int)x : (int)y;

where device is (currently) a gswindow_device_t pointer (so you can get 
all the info you need quickly).  I also added an informal protocol for 
communication between the window server and graphics drivers that handle 
backing store, so you might implement in the graphics driver:

- (void) GSSetDevice: (void*)device : (int)x : (int)y
{
  gswindow_device_t *gswin = device;

  window = gswin->ident;

  /* Tell the server we will do backing */
  gswin->gdriverProtocol = (GSDriverHandlesBacking | 
GSDriverHandlesExpose);

  /* Insert a pointer to our backing device handler */
  gswin->gdriver = mywindriver;
}


Then when the window needs to be flushed or exposed, you will receive a 
message where you can flush the window:

+ (void) handleExposeRect: (NSRect)rect forDriver: (void *)driver
{
   MyWinDriver *wd = (MyWindDriver *)driver;
   [wd flushRect: rect];
}

I think this interface is really just temporary to help you work on the 
graphics part and see how fast it can be without having to 
double-buffer, but in fact this interface makes it nearly impossible to 
have more than one context draw into a window (say, if you had an 
NSOpenGLView). It also forces the graphics driver to know lots of stuff 
about the window server (like is it X11 or Windows).
Eventually we will have to agree on a common buffer format which you can 
write to and the window server can read which is server independant (if 
that's possible - it may not be if we want decent graphics performace).






--
Adam Fedor, Digital Optics Corp.      | I'm glad I hate spinach, because
http://www.doc.com                    | if I didn't, I'd eat it, and you
                                      | know how I hate the stuff.