class Gdk::FrameClock


A Gdk::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.

Gdk::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 Gdk::FrameClock#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 Gdk::FrameClock class for documentation of the phases. %GDK_FRAME_CLOCK_PHASE_UPDATE and the Gdk::FrameClock::#update signal are most interesting for application writers, and are used to update the animations, using the frame time given by Gdk::FrameClock#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::FrameClock#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::FrameClock#frame_time and the value inside the Gdk::FrameClock::#update signal of the clock, they will stay exactly synchronized.

Defined in:



Class Method Summary

Instance Method Summary

Instance methods inherited from class GObject::Object

==(other : self) ==, bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding bind_property, bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding bind_property_full, data(key : String) : Pointer(Void) | Nil data, finalize finalize, freeze_notify : Nil freeze_notify, getv(names : Enumerable(String), values : Enumerable(_)) : Nil getv, hash(hasher) hash, notify(property_name : String) : Nil notify, notify_by_pspec(pspec : GObject::ParamSpec) : Nil notify_by_pspec, notify_signal notify_signal, property(property_name : String, value : _) : Nil property, qdata(quark : UInt32) : Pointer(Void) | Nil qdata, ref_count : UInt32 ref_count, run_dispose : Nil run_dispose, set_data(key : String, data : Pointer(Void) | Nil) : Nil set_data, set_property(property_name : String, value : _) : Nil set_property, steal_data(key : String) : Pointer(Void) | Nil steal_data, steal_qdata(quark : UInt32) : Pointer(Void) | Nil steal_qdata, thaw_notify : Nil thaw_notify, to_unsafe : Pointer(Void) to_unsafe, watch_closure(closure : GObject::Closure) : Nil watch_closure

Constructor methods inherited from class GObject::Object

cast(obj : GObject::Object) : self cast, new(pointer : Pointer(Void), transfer : GICrystal::Transfer)
, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv

Class methods inherited from class GObject::Object

cast?(obj : GObject::Object) : self | Nil cast?, compat_control(what : UInt64, data : Pointer(Void) | Nil) : UInt64 compat_control, g_type : UInt64 g_type, interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec interface_find_property, interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec) interface_list_properties

Macros inherited from class GObject::Object

previous_vfunc(*args) previous_vfunc, previous_vfunc!(*args) previous_vfunc!, signal(signature) signal

Constructor Detail

def #

Initialize a new FrameClock.

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Class Method Detail

def self.g_type : UInt64 #

Returns the type id (GType) registered in GLib type system.

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Instance Method Detail

def ==(other : self) #
Description copied from class Reference

Returns true if this reference is the same as other. Invokes same?.

def after_paint_signal #

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def before_paint_signal #

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def begin_updating : Nil #

Starts updates for an animation.

Until a matching call to Gdk::FrameClock#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.

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def current_timings : Gdk::FrameTimings | Nil #

Gets the frame timings for the current frame.

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def end_updating : Nil #

Stops updates for an animation.

See the documentation for Gdk::FrameClock#begin_updating.

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def flush_events_signal #

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def fps : Float64 #

Calculates the current frames-per-second, based on the frame timings of frame_clock.

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def frame_counter : Int64 #

Gdk::FrameClock maintains a 64-bit counter that increments for each frame drawn.

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def frame_time : Int64 #

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.

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def hash(hasher) #
Description copied from class Reference

See Object#hash(hasher)

def history_start : Int64 #

Returns the frame counter for the oldest frame available in history.

Gdk::FrameClock internally keeps a history of Gdk::FrameTimings objects for recent frames that can be retrieved with Gdk::FrameClock#timings. The set of stored frames is the set from the counter values given by Gdk::FrameClock#history_start and Gdk::FrameClock#frame_counter, inclusive.

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def layout_signal #

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def paint_signal #

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def refresh_info(base_time : Int64, presentation_time_return : Int64) : Nil #

Predicts a presentation time, based on history.

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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def request_phase(phase : Gdk::FrameClockPhase) : Nil #

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::FrameClock#begin_updating instead, since this allows GTK to adjust system parameters to get maximally smooth animations.

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def resume_events_signal #

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def timings(frame_counter : Int64) : Gdk::FrameTimings | Nil #

Retrieves a Gdk::FrameTimings object holding timing information for the current frame or a recent frame.

The Gdk::FrameTimings object may not yet be complete: see Gdk::FrameTimings#complete and Gdk::FrameClock#history_start.

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def update_signal #

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