Re: Modernizing the display loop

[Owen Taylor <otaylor redhat com>]

Please ignore this for now for now - sent accidentally when not finished
- will send a finished version in the next day or two.

- Owen

On Mon, 2011-12-12 at 11:27 -0500, Owen Taylor wrote:
> My current large-scale project is to get proper coordination between the
> application and window system for timing.
> 
> Window Clocks
> ==============
> 
> My basic idea is to have a "Window Clock" object that serves as the
> central point of timing coordination for each toplevel window.
> 
>  /* Get the singleton window clock for a toplevel window */
>  GdkWindowClock *gdk_window_get_clock (GdkWindow *window);
> 
> The window clock object has two signals:
> 
>  ::layout
>  ::draw
> 
> With corresponding methods:
> 
>  gdk_window_clock_queue_layout (GdkWindowClock *clock);
>  gdk_window_clock_queue_draw   (GdkWindowClock *clock);
> 
> It also has can have any number of "clock targets" objects added to it:
> 
>  void gdk_window_clock_add    (GdkWindowClock *clock,
>                                GdkClockTarget *target);
>  void gdk_window_clock_remove (GdkWindowClock *clock,
>                                GdkClockTarget *target);
> 
> GdkClockTarget is a simple interface:
> 
>  struct _GdkClockTargetClass {
>      GTypeInterface base_iface;
> 
>      void (*update) (GdkClockTarget  target,
>                      GdkWindowClock *clock);
>  };
> 
> When there is at least one clock target added, the clock is "on", and
> whenever it's time to draw a frame, each clock is updated.
> 
> Event compression
> =================
> 
> Cross-platform issues
> =====================
> 
> I spent some time looking at what windowing system capabilities we'd
> want to hook this into on Windows and the Mac. It seemed like on the
> Mac, you might want to hook this up to CVDisplayLink
> 
> http://developer.apple.com/library/mac/#documentation/QuartzCore/Reference/CVDisplayLinkRef/Reference/reference.html
> 
> On Windows (Vista, 7), the Desktop Window Manager APIs allow querying
> for information about how the scree is being updated:
> 
> 
> - Owen
> 
> 
> 
> 
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