carousel_strategy.hpp

#pragma once
 
#include <QVector>
#include <Qt>
 
namespace qml_material
{
 
// Keep in sync with MD.Enum.CarouselLayout (include/qml_material/core/enum.hpp).
namespace CarouselLayoutId
{
constexpr int Uncontained            = 0;
constexpr int MultiBrowse            = 1;
constexpr int Hero                   = 2;
constexpr int HeroCenter             = 3;
constexpr int FullScreen             = 4;
constexpr int UncontainedMultiAspect = 5;
} // namespace CarouselLayoutId
 
// Keep in sync with qml_material::token::Carousel (MD.Token.carousel).
struct CarouselEngineDefaults
{
    static constexpr qreal min_peek_px                = 16;
    static constexpr qreal parallax_ratio             = 0.35;
    static constexpr qreal parallax_ratio_uncontained = 0.5;
    static constexpr int   snap_duration              = 400;
    static constexpr qreal min_item_aspect            = 9.0 / 16.0;
    static constexpr qreal max_item_aspect            = 16.0 / 9.0;
};
 
struct CarouselItemGeometry
{
    int   index         = 0;
    qreal position      = 0;
    qreal size          = 0;
    qreal mask_start    = 0;
    qreal mask_end      = 0;
    qreal parallax_shift = 0;
    int   size_class    = 2; // CarouselSizeLarge
};
 
struct CarouselLayoutInput
{
    int     layout            = 0;
    Qt::Orientation orientation = Qt::Horizontal;
    qreal   viewport_size     = 0;
    qreal   cross_size        = 0;
    qreal   scroll_offset     = 0;
    qreal   item_extent       = 180;
    qreal   spacing           = 8;
    qreal   small_item_min    = 40;
    qreal   small_item_max    = 56;
    qreal   content_padding_start = 0;
    qreal   content_padding_end   = 0;
    qreal   content_padding_cross = 0;
    qreal   min_peek_px       = 16;
    qreal   item_corner_radius = 28;
    qreal   parallax_ratio    = 0.35;
    qreal   min_item_aspect   = 9.0 / 16.0;
    qreal   max_item_aspect   = 16.0 / 9.0;
    int     count             = 0;
    bool    reduce_motion     = false;
    QVector<qreal> item_aspects;
};
 
struct CarouselLayoutOutput
{
    QVector<CarouselItemGeometry> items;
    QVector<qreal>                snap_offsets;
    qreal                         content_size       = 0;
    qreal                         max_scroll_offset  = 0;
    qreal                         end_snap_offset    = 0;
    qreal                         scroll_step        = 0;
    int                           leading_index      = 0;
};
 
class CarouselStrategy
{
public:
    static auto compute(const CarouselLayoutInput& input) -> CarouselLayoutOutput;
};
 
} // namespace qml_material