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| void | after-paint | Run Last |
| void | before-paint | Run Last |
| void | flush-events | Run Last |
| void | layout | Run Last |
| void | paint | Run Last |
| void | resume-events | Run Last |
| void | update | Run Last |
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
“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 “update” signal of the clock,
they will stay exactly synchronized.
gint64
gdk_frame_clock_get_frame_time (GdkFrameClock *frame_clock);
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
void gdk_frame_clock_request_phase (GdkFrameClock *frame_clock,GdkFrameClockPhase 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
void
gdk_frame_clock_begin_updating (GdkFrameClock *frame_clock);
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
void
gdk_frame_clock_end_updating (GdkFrameClock *frame_clock);
Stops updates for an animation. See the documentation for
gdk_frame_clock_begin_updating().
Since: 3.8
gint64
gdk_frame_clock_get_frame_counter (GdkFrameClock *frame_clock);
A GdkFrameClock maintains a 64-bit counter that increments for each frame drawn.
inside frame processing, the value of the frame counter for the current frame. Outside of frame processing, the frame counter for the last frame.
Since: 3.8
gint64
gdk_frame_clock_get_history_start (GdkFrameClock *frame_clock);
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.
the frame counter value for the oldest frame that is available in the internal frame history of the GdkFrameClock.
Since: 3.8
GdkFrameTimings * gdk_frame_clock_get_timings (GdkFrameClock *frame_clock,gint64 frame_counter);
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().
the GdkFrameTimings object for
the specified frame, or NULL if it is not available. See
gdk_frame_clock_get_history_start().
[nullable][transfer none]
Since: 3.8
GdkFrameTimings *
gdk_frame_clock_get_current_timings (GdkFrameClock *frame_clock);
Gets the frame timings for the current frame.
the GdkFrameTimings for the
frame currently being processed, or even no frame is being
processed, for the previous frame. Before any frames have been
processed, returns NULL.
[nullable][transfer none]
Since: 3.8
void gdk_frame_clock_get_refresh_info (GdkFrameClock *frame_clock,gint64 base_time,gint64 *refresh_interval_return,gint64 *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
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frame_clock |
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base_time |
base time for determining a presentaton time |
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refresh_interval_return |
a location to store the
determined refresh interval, or |
[out][optional] |
presentation_time_return |
a location to store the next candidate presentation time after the given base time. 0 will be will be stored if no history is present. |
[out] |
Since: 3.8
GdkFrameClockPhase is used to represent the different paint clock phases that can be requested. The elements of the enumeration correspond to the signals of GdkFrameClock.
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no phase |
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corresponds to GdkFrameClock::flush-events. Should not be handled by applications. |
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corresponds to GdkFrameClock::before-paint. Should not be handled by applications. |
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corresponds to GdkFrameClock::update. |
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corresponds to GdkFrameClock::layout. |
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corresponds to GdkFrameClock::paint. |
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corresponds to GdkFrameClock::resume-events. Should not be handled by applications. |
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corresponds to GdkFrameClock::after-paint. Should not be handled by applications. |
Since: 3.8
“after-paint” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
This signal ends processing of the frame. Applications should generally not handle this signal.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“before-paint” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
This signal begins processing of the frame. Applications should generally not handle this signal.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“flush-events” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
This signal is used to flush pending motion events that are being batched up and compressed together. Applications should not handle this signal.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“layout” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
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.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“paint” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
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+ “draw” signals.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“resume-events” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
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.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last
“update” signalvoid user_function (GdkFrameClock *clock, gpointer user_data)
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.
clock |
the frame clock emitting the signal |
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user_data |
user data set when the signal handler was connected. |
Flags: Run Last