include/rive/scroll_event.hpp

#ifndef _RIVE_SCROLL_EVENT_HPP_
#define _RIVE_SCROLL_EVENT_HPP_

#include "rive/math/vec2d.hpp"
#include <stdint.h>

namespace rive
{
/// Where a scroll event sits within its gesture. A phaseless wheel only ever
/// reports update.
enum class ScrollPhase : uint8_t
{
  /// Stops any running fling and primes velocity tracking.
  begin = 0,

  update = 1,

  /// Contact ended; the runtime flings from the velocity it accumulated.
  /// Hosts whose platform generates its own momentum never send this.
  end = 2,

  /// Platform-generated after release. Applied directly, never flung on top
  /// of; closed by going idle rather than by an end.
  momentum = 3,

  /// Contact landed during momentum. Halts motion; delta is ignored.
  inertiaCancel = 4,
};

/// A scroll delta from indirect input: a wheel, or a trackpad gesture the
/// platform already classified as a scroll. Direct touch stays on the pointer
/// path.
struct ScrollEvent
{
  /// Distance the content moves, in artboard-space pixels -- the same sense
  /// as ScrollConstraint::dragView, so revealing later content is negative.
  /// Hosts normalize; the runtime never sees platform units.
  /// Zero unless set: Vec2D leaves its fields uninitialized, and a stray
  /// delta on a begin would claim a view the gesture never picked.
  Vec2D delta = Vec2D(0.0f, 0.0f);

  ScrollPhase phase = ScrollPhase::update;

  /// Pixel-precise source (trackpad) rather than a detented wheel.
  bool precise = false;
};

/// A gesture that reports no end of its own, like a wheel or platform
/// momentum, closes after this long without events.
constexpr float scrollIdleSeconds = 0.1f;
} // namespace rive

#endif