FrameClock
Object Hierarchy:
Description:
[
CCode ( type_id =
"gdk_frame_clock_get_type ()" ) ]
public abstract class FrameClock :
Object
A FrameClock tells the application when to update and repaint a surface.
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.
FrameClock 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 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 FrameClock class for documentation of the phases.
gdk_frame_clock_phase_update and the update
signal are most interesting for application writers, and are used to update the animations, using the frame time given by
get_frame_time.
The frame time is reported in microseconds and generally in the same timescale as
get_monotonic_time, however, it is not the same as
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
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
get_frame_time and the value inside the
update signal of the clock, they will stay exactly synchronized.
Content:
Creation methods:
Methods:
- public void begin_updating ()
Starts updates for an animation.
- public void end_updating ()
Stops updates for an animation.
- public unowned FrameTimings? get_current_timings ()
Gets the frame timings for the current frame.
- public double get_fps ()
Calculates the current frames-per-second, based on the frame timings of
this.
- public int64 get_frame_counter ()
A FrameClock maintains a 64-bit counter
that increments for each frame drawn.
- public int64 get_frame_time ()
Gets the time that should currently be used for animations.
- public int64 get_history_start ()
FrameClock internally keeps a history of
FrameTimings objects for recent frames that can be retrieved with
get_timings.
- public void get_refresh_info (int64 base_time, out int64 refresh_interval_return, out int64 presentation_time_return)
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.
- public unowned FrameTimings? get_timings (int64 frame_counter)
Retrieves a FrameTimings
object holding timing information for the current frame or a recent frame.
- public void request_phase (FrameClockPhase phase)
Asks the frame clock to run a particular phase.
Signals:
- public signal void after_paint ()
This signal ends processing of the frame.
- public signal void before_paint ()
This signal begins processing of the frame.
- public signal void flush_events ()
This signal is used to flush pending motion events that are being batched up
and compressed together.
- public signal void layout ()
This signal is emitted as the second step of toolkit and application
processing of the frame.
- public signal void paint ()
This signal is emitted as the third step of toolkit and application
processing of the frame.
- public signal void resume_events ()
This signal is emitted after processing of the frame is finished, and is
handled internally by GTK to resume normal event processing.
- public signal void update ()
This signal is emitted as the first step of toolkit and application
processing of the frame.
Inherited Members:
All known members inherited from class GLib.Object