Struct gdk4::FrameClock

#[repr(transparent)]
pub struct FrameClock { /* private fields */ }

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. FrameClockPhase::UPDATE and the signal::GdkFrameClock::update signal are most interesting for application writers, and are used to update the animations, using the frame time given by 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 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 frame_time() and the value inside the signal::GdkFrameClock::update signal of the clock, they will stay exactly synchronized.

This is an Abstract Base Class, you cannot instantiate it.

Implementations

impl FrameClock

pub fn begin_updating(&self)

Starts updates for an animation.

Until a matching call to end_updating() is made, the frame clock will continually request a new frame with the FrameClockPhase::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.

pub fn end_updating(&self)

Stops updates for an animation.

See the documentation for begin_updating().

pub fn current_timings(&self) -> Option<FrameTimings>

Gets the frame timings for the current frame.

Returns

the FrameTimings for the frame currently being processed, or even no frame is being processed, for the previous frame. Before any frames have been processed, returns None.

pub fn fps(&self) -> f64

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

Returns

the current fps, as a double

pub fn frame_counter(&self) -> i64

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

Returns

inside frame processing, the value of the frame counter for the current frame. Outside of frame processing, the frame counter for the last frame.

pub fn frame_time(&self) -> i64

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.

Returns

a timestamp in microseconds, in the timescale of of g_get_monotonic_time().

pub fn history_start(&self) -> i64

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

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

Returns

the frame counter value for the oldest frame that is available in the internal frame history of the FrameClock

pub fn refresh_info(&self, base_time: i64) -> (i64, i64)

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.

base_time

base time for determining a presentaton time

Returns

refresh_interval_return

a location to store the determined refresh interval, or None. A default refresh interval of 1/60th of a second will be stored if no history is present.

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.

pub fn timings(&self, frame_counter: i64) -> Option<FrameTimings>

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

The FrameTimings object may not yet be complete: see FrameTimings::is_complete() and history_start().

frame_counter

the frame counter value identifying the frame to be received

Returns

the FrameTimings object for the specified frame, or None if it is not available

pub fn request_phase(&self, phase: FrameClockPhase)

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 FrameClockPhase::UPDATE phase for a period of time, you should use begin_updating() instead, since this allows GTK to adjust system parameters to get maximally smooth animations.

phase

the phase that is requested

pub fn connect_after_paint<F: Fn(&Self) + 'static>( &self, f: F ) -> SignalHandlerId

This signal ends processing of the frame.

Applications should generally not handle this signal.

pub fn connect_before_paint<F: Fn(&Self) + 'static>( &self, f: F ) -> SignalHandlerId

Begins processing of the frame.

Applications should generally not handle this signal.

pub fn connect_flush_events<F: Fn(&Self) + 'static>( &self, f: F ) -> SignalHandlerId

Used to flush pending motion events that are being batched up and compressed together.

Applications should not handle this signal.

pub fn connect_layout<F: Fn(&Self) + 'static>(&self, f: F) -> SignalHandlerId

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.

pub fn connect_paint<F: Fn(&Self) + 'static>(&self, f: F) -> SignalHandlerId

Emitted as the third step of toolkit and application processing of the frame.

The frame is repainted. GDK normally handles this internally and emits signal::Surface::render signals which are turned into signal::Gtk::Widget::snapshot signals by GTK.

pub fn connect_resume_events<F: Fn(&Self) + 'static>( &self, f: F ) -> SignalHandlerId

Emitted after processing of the frame is finished.

This signal is handled internally by GTK to resume normal event processing. Applications should not handle this signal.

pub fn connect_update<F: Fn(&Self) + 'static>(&self, f: F) -> SignalHandlerId

Emitted as the first step of toolkit and application processing of the frame.

Animations should be updated using frame_time(). Applications can connect directly to this signal, or use Gtk::Widget::add_tick_callback() as a more convenient interface.

Trait Implementations

impl Clone for FrameClock

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FrameClock

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for FrameClock

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for FrameClock

fn hash<H>(&self, state: &mut H)where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for FrameClock

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl ParentClassIs for FrameClock

type Parent = Object

impl<OT: ObjectType> PartialEq<OT> for FrameClock

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<OT: ObjectType> PartialOrd<OT> for FrameClock

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for FrameClock

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for FrameClock