Class
GdkFrameClock
Description [src]
abstract class Gdk.FrameClock : GObject.Object
{
/* No available fields */
}A GdkFrameClock tells the application when to update and repaint a
window. This may be synced to the vertical refresh rate of the
monitor, for example. Even when the frame clock uses a simple timer
rather than a hardware-based vertical sync, the frame clock helps
because it ensures everything paints at the same time (reducing the
total number of frames). The frame clock can also automatically
stop painting when it knows the frames will not be visible, or
scale back animation framerates.
GdkFrameClock is designed to be compatible with an OpenGL-based
implementation or with mozRequestAnimationFrame in Firefox,
for example.
A frame clock is idle until someone requests a frame with
gdk_frame_clock_request_phase(). At some later point that makes
sense for the synchronization being implemented, the clock will
process a frame and emit signals for each phase that has been
requested. (See the signals of the GdkFrameClock class for
documentation of the phases. GDK_FRAME_CLOCK_PHASE_UPDATE and the
GdkFrameClock::update signal are most interesting for application
writers, and are used to update the animations, using the frame time
given by gdk_frame_clock_get_frame_time().
The frame time is reported in microseconds and generally in the same
timescale as g_get_monotonic_time(), however, it is not the same
as g_get_monotonic_time(). The frame time does not advance during
the time a frame is being painted, and outside of a frame, an attempt
is made so that all calls to gdk_frame_clock_get_frame_time() that
are called at a “similar” time get the same value. This means that
if different animations are timed by looking at the difference in
time between an initial value from gdk_frame_clock_get_frame_time()
and the value inside the GdkFrameClock::update signal of the clock,
they will stay exactly synchronized.
Instance methods
gdk_frame_clock_begin_updating
Starts updates for an animation. Until a matching call to
gdk_frame_clock_end_updating() is made, the frame clock will continually
request a new frame with the GDK_FRAME_CLOCK_PHASE_UPDATE phase.
This function may be called multiple times and frames will be
requested until gdk_frame_clock_end_updating() is called the same
number of times.
since: 3.8
gdk_frame_clock_end_updating
Stops updates for an animation. See the documentation for gdk_frame_clock_begin_updating().
since: 3.8
gdk_frame_clock_get_frame_counter
A GdkFrameClock maintains a 64-bit counter that increments for
each frame drawn.
since: 3.8
gdk_frame_clock_get_frame_time
Gets the time that should currently be used for animations. Inside the processing of a frame, it’s the time used to compute the animation position of everything in a frame. Outside of a frame, it’s the time of the conceptual “previous frame,” which may be either the actual previous frame time, or if that’s too old, an updated time.
since: 3.8
gdk_frame_clock_get_history_start
GdkFrameClock internally keeps a history of GdkFrameTimings
objects for recent frames that can be retrieved with
gdk_frame_clock_get_timings(). The set of stored frames
is the set from the counter values given by
gdk_frame_clock_get_history_start() and
gdk_frame_clock_get_frame_counter(), inclusive.
since: 3.8
gdk_frame_clock_get_refresh_info
Using the frame history stored in the frame clock, finds the last
known presentation time and refresh interval, and assuming that
presentation times are separated by the refresh interval,
predicts a presentation time that is a multiple of the refresh
interval after the last presentation time, and later than base_time.
since: 3.8
gdk_frame_clock_get_timings
Retrieves a GdkFrameTimings object holding timing information
for the current frame or a recent frame. The GdkFrameTimings
object may not yet be complete: see gdk_frame_timings_get_complete().
since: 3.8
gdk_frame_clock_request_phase
Asks the frame clock to run a particular phase. The signal
corresponding the requested phase will be emitted the next
time the frame clock processes. Multiple calls to
gdk_frame_clock_request_phase() will be combined together
and only one frame processed. If you are displaying animated
content and want to continually request the
GDK_FRAME_CLOCK_PHASE_UPDATE phase for a period of time,
you should use gdk_frame_clock_begin_updating() instead, since
this allows GTK+ to adjust system parameters to get maximally
smooth animations.
since: 3.8
Signals
Gdk.FrameClock::after-paint
This signal ends processing of the frame. Applications should generally not handle this signal.
Gdk.FrameClock::before-paint
This signal begins processing of the frame. Applications should generally not handle this signal.
Gdk.FrameClock::flush-events
This signal is used to flush pending motion events that are being batched up and compressed together. Applications should not handle this signal.
Gdk.FrameClock::layout
This signal is emitted as the second step of toolkit and application processing of the frame. Any work to update sizes and positions of application elements should be performed. GTK+ normally handles this internally.
Gdk.FrameClock::paint
This signal is emitted as the third step of toolkit and
application processing of the frame. The frame is
repainted. GDK normally handles this internally and
produces expose events, which are turned into GTK+
GtkWidget::draw signals.
Gdk.FrameClock::resume-events
This signal is emitted after processing of the frame is finished, and is handled internally by GTK+ to resume normal event processing. Applications should not handle this signal.
Gdk.FrameClock::update
This signal is emitted as the first step of toolkit and
application processing of the frame. Animations should
be updated using gdk_frame_clock_get_frame_time().
Applications can connect directly to this signal, or
use gtk_widget_add_tick_callback() as a more convenient interface.
Signals inherited from GObject (1)
GObject::notify
The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.