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#include "kinetic_scroller.hpp"
#include "visual_params.hpp"
#include "indexer/scales.hpp"
#include "base/logging.hpp"
namespace df
{
double const kKineticDuration = 1.5;
double const kKineticFadeoff = 4.0;
double const kKineticThreshold = 50.0;
double const kKineticAcceleration = 0.4;
double const kKineticMaxSpeedStart = 1000.0; // pixels per second
double const kKineticMaxSpeedEnd = 10000.0; // pixels per second
double CalculateKineticMaxSpeed(ScreenBase const & modelView)
{
double const lerpCoef = 1.0 - GetNormalizedZoomLevel(modelView.GetScale());
return (kKineticMaxSpeedStart * lerpCoef + kKineticMaxSpeedEnd * (1.0 - lerpCoef)) * VisualParams::Instance().GetVisualScale();
}
class KineticScrollAnimation : public Animation
{
public:
// startRect - mercator visible on screen rect in moment when user release fingers.
// direction - mercator space direction of moving. length(direction) - mercator distance on wich map will be offset.
KineticScrollAnimation(m2::PointD const & startPos, m2::PointD const & direction, double duration)
: Animation(true /* couldBeInterrupted */, true /* couldBeBlended */)
, m_endPos(startPos + direction)
, m_direction(direction)
, m_duration(duration)
, m_elapsedTime(0.0)
{
SetInterruptedOnCombine(true);
m_objects.insert(Animation::MapPlane);
m_properties.insert(Animation::Position);
}
Animation::Type GetType() const override { return Animation::KineticScroll; }
TAnimObjects const & GetObjects() const override
{
return m_objects;
}
bool HasObject(TObject object) const override
{
return m_objects.find(object) != m_objects.end();
}
TObjectProperties const & GetProperties(TObject object) const override
{
ASSERT(HasObject(object), ());
return m_properties;
}
bool HasProperty(TObject object, TProperty property) const override
{
return HasObject(object) && m_properties.find(property) != m_properties.end();
}
void SetMaxDuration(double maxDuration) override
{
if (m_duration > maxDuration)
m_duration = maxDuration;
}
double GetDuration() const override { return m_duration; }
bool IsFinished() const override { return m_elapsedTime >= m_duration; }
void Advance(double elapsedSeconds) override
{
m_elapsedTime += elapsedSeconds;
}
void Finish() override
{
m_elapsedTime = m_duration;
Animation::Finish();
}
bool GetProperty(TObject object, TProperty property, PropertyValue & value) const override
{
ASSERT(HasProperty(object, property), ());
// Current position = target position - amplutide * e ^ (elapsed / duration).
// We calculate current position not based on start position, but based on target position.
value = PropertyValue(m_endPos - m_direction * exp(-kKineticFadeoff * GetT()));
return true;
}
bool GetTargetProperty(TObject object, TProperty property, PropertyValue & value) const override
{
ASSERT(HasProperty(object, property), ());
value = PropertyValue(m_endPos);
return true;
}
private:
double GetT() const
{
return IsFinished() ? 1.0 : m_elapsedTime / m_duration;
}
m2::PointD m_endPos;
m2::PointD m_direction;
double m_duration;
double m_elapsedTime;
TAnimObjects m_objects;
TObjectProperties m_properties;
};
KineticScroller::KineticScroller()
: m_lastTimestamp(-1.0)
, m_direction(m2::PointD::Zero())
{
}
void KineticScroller::InitGrab(ScreenBase const & modelView, double timeStamp)
{
ASSERT_LESS(m_lastTimestamp, 0.0, ());
m_lastTimestamp = timeStamp;
m_lastRect = modelView.GlobalRect();
}
bool KineticScroller::IsActive() const
{
return m_lastTimestamp > 0.0;
}
void KineticScroller::GrabViewRect(ScreenBase const & modelView, double timeStamp)
{
// In KineitcScroller we store m_direction in mixed state.
// Direction in mercator space, and length(m_direction) in pixel space.
// We need same reaction on different zoom levels, and should calculate velocity on pixel space.
ASSERT_GREATER(m_lastTimestamp, 0.0, ());
ASSERT_GREATER(timeStamp, m_lastTimestamp, ());
double elapsed = timeStamp - m_lastTimestamp;
m2::PointD lastCenter = m_lastRect.GlobalCenter();
m2::PointD currentCenter = modelView.GlobalRect().GlobalCenter();
double pxDeltaLength = (modelView.GtoP(currentCenter) - modelView.GtoP(lastCenter)).Length();
m2::PointD delta = (currentCenter - lastCenter);
if (!delta.IsAlmostZero())
{
delta = delta.Normalize();
// Velocity on pixels.
double const v = min(pxDeltaLength / elapsed, CalculateKineticMaxSpeed(modelView));
// At this point length(m_direction) already in pixel space, and delta normalized.
m_direction = delta * v;
}
else
{
m_direction = m2::PointD::Zero();
}
m_lastTimestamp = timeStamp;
m_lastRect = modelView.GlobalRect();
}
void KineticScroller::CancelGrab()
{
m_lastTimestamp = -1;
m_direction = m2::PointD::Zero();
}
drape_ptr<Animation> KineticScroller::CreateKineticAnimation(ScreenBase const & modelView)
{
static double kVelocityThreshold = kKineticThreshold * VisualParams::Instance().GetVisualScale();
if (m_direction.Length() < kVelocityThreshold)
return drape_ptr<Animation>();
// Before we start animation we have to convert length(m_direction) from pixel space to mercator space.
m2::PointD center = m_lastRect.GlobalCenter();
double const offset = (modelView.PtoG(modelView.GtoP(center) + m_direction) - center).Length();
double const glbLength = kKineticAcceleration * offset;
m2::PointD const glbDirection = m_direction.Normalize() * glbLength;
m2::PointD const targetCenter = center + glbDirection;
if (!df::GetWorldRect().IsPointInside(targetCenter))
return drape_ptr<Animation>();
return make_unique_dp<KineticScrollAnimation>(center, glbDirection, kKineticDuration);
}
} // namespace df
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