Bug 1495 - Timelines run 4% short
Previously the timelines were timed by calculating the interval
between each frame stored as an integer number of milliseconds so some
precision is lost. For example, requesting 60 frames per second gets
converted to 16 ms per frame which is actually 62.5 frames per
second. This makes the timeline shorter by 4%.
This patch merges the common code for timing from the timeout pools
and frame sources into an internal clutter-timeout-interval file. This
stores the interval directly as the FPS and counts the number of
frames that have been reached instead of the elapsed time.
A ClutterTimeoutPool is a source for the GLib main loop which pools
multiple timeout functions. The pool is always sorted so that the first
timeout to expire is also the first element of the pool; hence, extraction
is a constant time operation. This also makes the usage of multiple
timeouts at the same priority not compete for a timeslice of the main
loop, leading to starvation.
