Class

GdkFrameClock

Description [src]

abstract class Gdk.FrameClock : GObject.Object {
  /* No available fields */
}

A GdkFrameClock 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.

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.

Hierarchy

hierarchy this GdkFrameClock ancestor_0 GObject ancestor_0--this

Ancestors

  • GObject

Instance methods

gdk_frame_clock_begin_updating

Starts updates for an animation.

gdk_frame_clock_end_updating

Stops updates for an animation.

gdk_frame_clock_get_current_timings

Gets the frame timings for the current frame.

gdk_frame_clock_get_fps

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

gdk_frame_clock_get_frame_counter

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

gdk_frame_clock_get_frame_time

Gets the time that should currently be used for animations.

gdk_frame_clock_get_history_start

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

gdk_frame_clock_get_refresh_info

Predicts a presentation time, based on history.

gdk_frame_clock_get_timings

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

gdk_frame_clock_request_phase

Asks the frame clock to run a particular phase.

Signals

Gdk.FrameClock::after-paint

This signal ends processing of the frame.

Gdk.FrameClock::before-paint

Begins processing of the frame.

Gdk.FrameClock::flush-events

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

Gdk.FrameClock::layout

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

Gdk.FrameClock::paint

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

Gdk.FrameClock::resume-events

Emitted after processing of the frame is finished.

Gdk.FrameClock::update

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

Class structure

struct GdkFrameClockClass {
  /* no available fields */
}