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Frame timings

Frame timings — Object holding timing information for a single frame

Types and Values

Includes

#include <gdk/gdk.h>

Description

A GdkFrameTimings object holds timing information for a single frame of the application’s displays. To retrieve GdkFrameTimings objects, use gdk_frame_clock_get_timings() or gdk_frame_clock_get_current_timings(). The information in GdkFrameTimings is useful for precise synchronization of video with the event or audio streams, and for measuring quality metrics for the application’s display, such as latency and jitter.

Functions

gdk_frame_timings_ref ()

GdkFrameTimings *
gdk_frame_timings_ref (GdkFrameTimings *timings);

Increases the reference count of timings .

Parameters

timings

a GdkFrameTimings

 

Returns

timings

Since: 3.8


gdk_frame_timings_unref ()

void
gdk_frame_timings_unref (GdkFrameTimings *timings);

Decreases the reference count of timings . If timings is no longer referenced, it will be freed.

Parameters

timings

a GdkFrameTimings

 

Since: 3.8


gdk_frame_timings_get_frame_counter ()

gint64
gdk_frame_timings_get_frame_counter (GdkFrameTimings *timings);

Gets the frame counter value of the GdkFrameClock when this this frame was drawn.

Parameters

timings

a GdkFrameTimings

 

Returns

the frame counter value for this frame

Since: 3.8


gdk_frame_timings_get_complete ()

gboolean
gdk_frame_timings_get_complete (GdkFrameTimings *timings);

The timing information in a GdkFrameTimings is filled in incrementally as the frame as drawn and passed off to the window system for processing and display to the user. The accessor functions for GdkFrameTimings can return 0 to indicate an unavailable value for two reasons: either because the information is not yet available, or because it isn't available at all. Once gdk_frame_timings_get_complete() returns TRUE for a frame, you can be certain that no further values will become available and be stored in the GdkFrameTimings.

Parameters

timings

a GdkFrameTimings

 

Returns

TRUE if all information that will be available for the frame has been filled in.

Since: 3.8


gdk_frame_timings_get_frame_time ()

gint64
gdk_frame_timings_get_frame_time (GdkFrameTimings *timings);

Returns the frame time for the frame. This is the time value that is typically used to time animations for the frame. See gdk_frame_clock_get_frame_time().

Parameters

timings

A GdkFrameTimings

 

Returns

the frame time for the frame, in the timescale of g_get_monotonic_time()


gdk_frame_timings_get_presentation_time ()

gint64
gdk_frame_timings_get_presentation_time
                               (GdkFrameTimings *timings);

Reurns the presentation time. This is the time at which the frame became visible to the user.

Parameters

timings

a GdkFrameTimings

 

Returns

the time the frame was displayed to the user, in the timescale of g_get_monotonic_time(), or 0 if no presentation time is available. See gdk_frame_timings_get_complete()

Since: 3.8


gdk_frame_timings_get_refresh_interval ()

gint64
gdk_frame_timings_get_refresh_interval
                               (GdkFrameTimings *timings);

Gets the natural interval between presentation times for the display that this frame was displayed on. Frame presentation usually happens during the “vertical blanking interval”.

Parameters

timings

a GdkFrameTimings

 

Returns

the refresh interval of the display, in microseconds, or 0 if the refresh interval is not available. See gdk_frame_timings_get_complete().

Since: 3.8


gdk_frame_timings_get_predicted_presentation_time ()

gint64
gdk_frame_timings_get_predicted_presentation_time
                               (GdkFrameTimings *timings);

Gets the predicted time at which this frame will be displayed. Although no predicted time may be available, if one is available, it will be available while the frame is being generated, in contrast to gdk_frame_timings_get_presentation_time(), which is only available after the frame has been presented. In general, if you are simply animating, you should use gdk_frame_clock_get_frame_time() rather than this function, but this function is useful for applications that want exact control over latency. For example, a movie player may want this information for Audio/Video synchronization.

Parameters

timings

a GdkFrameTimings

 

Returns

The predicted time at which the frame will be presented, in the timescale of g_get_monotonic_time(), or 0 if no predicted presentation time is available.

Since: 3.8

Types and Values

GdkFrameTimings

typedef struct _GdkFrameTimings GdkFrameTimings;
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