pulp::timeline_editor::UiPlayhead Struct Reference

One complete reading of where playback is. More...

#include <sequencer_ui_host.hpp>

Public Member Functions
constexpr bool	moving () const noexcept
	Whether the position advances on its own.
constexpr bool	operator== (const UiPlayhead &) const =default

Public Attributes
std::uint64_t	program_generation = 0
	Identity of the compiled program this reading came from.
std::uint64_t	sequence = 0
	Monotonic per publish.
std::uint64_t	continuity_epoch = 0
	Identity of the continuous interval this reading's position belongs to.
timebase::TickPosition	position {}
	Document position. This is the value a ruler and a playhead line draw.
timebase::LoopRegion	loop {}
UiTransportState	state = UiTransportState::Stopped
double	tempo_bpm = 120.0

Detailed Description

One complete reading of where playback is.

Every field is a value. Holding a UiPlayhead across a program swap, a seek, or the destruction of the host's engine is defined: the reading goes stale, never invalid. program_generation is how a view tells stale from live without holding anything a swap can invalidate — it changes on every program adoption, so a view comparing two readings knows whether they describe the same compiled world.

continuity_epoch answers the other question a view has about two readings, and program_generation cannot answer it: whether the position moved continuously between them. A loop wrap, a seek, and a latched scrub anchor all break continuity without recompiling anything, so the generation is unchanged across exactly the discontinuities a drawn playhead must not smooth over.

Member Function Documentation

moving()

bool pulp::timeline_editor::UiPlayhead::moving ( ) const

inlineconstexprnoexcept

Whether the position advances on its own.

True while scrubbing, because a scrub moves the playhead even though the musical transport is stopped.

operator==()

bool pulp::timeline_editor::UiPlayhead::operator== ( const UiPlayhead & ) const

constexprdefault

Member Data Documentation

continuity_epoch

std::uint64_t pulp::timeline_editor::UiPlayhead::continuity_epoch = 0

Identity of the continuous interval this reading's position belongs to.

A view must not interpolate position across a change in this value: the two readings name positions in different intervals, and a line drawn between them travels ground the playhead never covered — backwards through the whole timeline, on a loop wrap. Hold the newer reading's position outright instead, and resume interpolating from there.

loop

timebase::LoopRegion pulp::timeline_editor::UiPlayhead::loop {}

position

timebase::TickPosition pulp::timeline_editor::UiPlayhead::position {}

Document position. This is the value a ruler and a playhead line draw.

program_generation

std::uint64_t pulp::timeline_editor::UiPlayhead::program_generation = 0

Identity of the compiled program this reading came from.

Monotonic; a change means the engine adopted a different program between readings.

sequence

std::uint64_t pulp::timeline_editor::UiPlayhead::sequence = 0

Monotonic per publish.

Two readings with the same value are the same reading, which is how a view skips redundant repaints.

state

UiTransportState pulp::timeline_editor::UiPlayhead::state = UiTransportState::Stopped

tempo_bpm

double pulp::timeline_editor::UiPlayhead::tempo_bpm = 120.0

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The documentation for this struct was generated from the following file:

• /home/runner/work/pulp/pulp/core/timeline_editor/include/pulp/timeline_editor/sequencer_ui_host.hpp