Class FrameClock

java.lang.Object
org.javagi.base.ProxyInstance
org.gnome.gobject.TypeInstance
org.gnome.gobject.GObject
org.gnome.gdk.FrameClock
All Implemented Interfaces:
Proxy
Direct Known Subclasses:
FrameClock.FrameClock$Impl
@Generated("org.javagi.JavaGI") public abstract class FrameClock extends GObject

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 requestPhase(Set). 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. FrameClockPhase.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 getFrameTime().

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 getFrameTime() 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 getFrameTime() and the value inside the Gdk.FrameClock::update signal of the clock, they will stay exactly synchronized.

  • Constructor Details

    • FrameClock

      public FrameClock(MemorySegment address)
      Create a FrameClock instance for the provided memory address.
      Parameters:
      address - the memory address of the native object

    • FrameClock

      public FrameClock()
      Create a new FrameClock.

  • Method Details

    • getType

      public static @Nullable Type getType()
      Get the GType of the FrameClock class.
      Returns:
      the GType

    • getMemoryLayout

      public static MemoryLayout getMemoryLayout()
      The memory layout of the native struct.
      Returns:
      the memory layout

    • asParent

      protected FrameClock asParent()
      Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.
      Overrides:
      asParent in class GObject
      Returns:
      the instance as if it were its parent type

    • beginUpdating

      public void beginUpdating()

      Starts updates for an animation.

      Until a matching call to endUpdating() 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.

    • endUpdating

      public void endUpdating()

      Stops updates for an animation.

      See the documentation for beginUpdating().

    • getCurrentTimings

      public @Nullable FrameTimings getCurrentTimings()
      Gets the frame timings for the current frame.
      Returns:
      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.

    • getFps

      public double getFps()
      Calculates the current frames-per-second, based on the frame timings of frameClock.
      Returns:
      the current fps, as a double

    • getFrameCounter

      public long getFrameCounter()
      GdkFrameClock 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.

    • getFrameTime

      public long getFrameTime()

      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().

    • getHistoryStart

      public long getHistoryStart()

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

      GdkFrameClock internally keeps a history of GdkFrameTimings objects for recent frames that can be retrieved with getTimings(long). The set of stored frames is the set from the counter values given by getHistoryStart() and getFrameCounter(), inclusive.

      Returns:
      the frame counter value for the oldest frame that is available in the internal frame history of the GdkFrameClock

    • getRefreshInfo

      public void getRefreshInfo(long baseTime, @Nullable Out<Long> refreshIntervalReturn, Out<Long> presentationTimeReturn)

      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 baseTime.

      Parameters:
      baseTime - base time for determining a presentaton time
      refreshIntervalReturn - a location to store the determined refresh interval, or null. A default refresh interval of 1/60th of a second will be stored if no history is present.
      presentationTimeReturn - 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.

    • getTimings

      public @Nullable FrameTimings getTimings(long frameCounter)

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

      The GdkFrameTimings object may not yet be complete: see FrameTimings.getComplete() and getHistoryStart().

      Parameters:
      frameCounter - the frame counter value identifying the frame to be received
      Returns:
      the GdkFrameTimings object for the specified frame, or null if it is not available

    • requestPhase

      public void requestPhase(Set<FrameClockPhase> 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 FrameClockPhase.UPDATE phase for a period of time, you should use beginUpdating() instead, since this allows GTK to adjust system parameters to get maximally smooth animations.

      Parameters:
      phase - the phase that is requested

    • requestPhase

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

      Parameters:
      phase - the phase that is requested

    • onAfterPaint

      public SignalConnection<FrameClock.AfterPaintCallback> onAfterPaint(FrameClock.AfterPaintCallback handler)

      This signal ends processing of the frame.

      Applications should generally not handle this signal.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitAfterPaint

      public void emitAfterPaint()
      Emits the "after-paint" signal. See onAfterPaint(FrameClock.AfterPaintCallback).

    • onBeforePaint

      public SignalConnection<FrameClock.BeforePaintCallback> onBeforePaint(FrameClock.BeforePaintCallback handler)

      Begins processing of the frame.

      Applications should generally not handle this signal.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitBeforePaint

      public void emitBeforePaint()
      Emits the "before-paint" signal. See onBeforePaint(FrameClock.BeforePaintCallback).

    • onFlushEvents

      public SignalConnection<FrameClock.FlushEventsCallback> onFlushEvents(FrameClock.FlushEventsCallback handler)

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

      Applications should not handle this signal.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitFlushEvents

      public void emitFlushEvents()
      Emits the "flush-events" signal. See onFlushEvents(FrameClock.FlushEventsCallback).

    • onLayout

      public SignalConnection<FrameClock.LayoutCallback> onLayout(FrameClock.LayoutCallback handler)

      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.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitLayout

      public void emitLayout()
      Emits the "layout" signal. See onLayout(FrameClock.LayoutCallback).

    • onPaint

      public SignalConnection<FrameClock.PaintCallback> onPaint(FrameClock.PaintCallback handler)

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

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

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitPaint

      public void emitPaint()
      Emits the "paint" signal. See onPaint(FrameClock.PaintCallback).

    • onResumeEvents

      public SignalConnection<FrameClock.ResumeEventsCallback> onResumeEvents(FrameClock.ResumeEventsCallback handler)

      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.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitResumeEvents

      public void emitResumeEvents()
      Emits the "resume-events" signal. See onResumeEvents(FrameClock.ResumeEventsCallback).

    • onUpdate

      public SignalConnection<FrameClock.UpdateCallback> onUpdate(FrameClock.UpdateCallback handler)

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

      Animations should be updated using getFrameTime(). Applications can connect directly to this signal, or use gtk_widget_add_tick_callback() as a more convenient interface.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitUpdate

      public void emitUpdate()
      Emits the "update" signal. See onUpdate(FrameClock.UpdateCallback).