carousel_strategy.hpp

#pragma once
 
#include <QVector>
#include <Qt>
#include "qml_material/token/duration.hpp"
 
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              = int(token::Duration {}.medium4);
    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