reorder_list.hpp

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#pragma once

 
#include <pulp/canvas/canvas.hpp>
#include <pulp/view/animation.hpp>
#include <pulp/view/geometry.hpp>
#include <pulp/view/view.hpp>
 
#include <functional>
#include <memory>
#include <vector>
 
namespace pulp::view {

int reorder_target_index(int from, float offset, float pitch, int count);

class ReorderList : public View {
public:
    enum class Orientation { vertical, horizontal };
 
    ReorderList() = default;

    void add_item(std::unique_ptr<View> item);
 
    int item_count() const { return static_cast<int>(items_.size()); }
    View* item_at(int i) const {
        return (i >= 0 && i < item_count()) ? items_[i] : nullptr;
    }

    int index_of(const View* v) const;
 
    void set_orientation(Orientation o) { orientation_ = o; }
    Orientation orientation() const { return orientation_; }
    void set_item_extent(float px) { item_extent_ = px; }  
    void set_gap(float px) { gap_ = px; }
    float pitch() const { return item_extent_ + gap_; }

    int dragging_index() const { return dragging_; }
    int drop_target_index() const { return target_; }

    std::function<void(int from, int to)> on_reorder;
 
    void layout_children() override;
    void paint(canvas::Canvas& canvas) override;
    void on_mouse_down(Point pos) override;
    void on_mouse_drag(Point pos) override;
    void on_mouse_up(Point pos) override;
    bool wants_mouse_input() const override { return true; }
 
private:
    // Main-axis coordinate of a point in this view's local space.
    float main_of(Point p) const {
        return orientation_ == Orientation::vertical ? p.y : p.x;
    }
    // Position item `display_index` at its resting slot (accounting for an
    // in-progress drag that opened a gap), writing its bounds.
    void position_item(int display_index) const;
 
    std::vector<View*> items_;   
    Orientation orientation_ = Orientation::vertical;
    float item_extent_ = 40.0f;
    float gap_ = 6.0f;
 
    int dragging_ = -1;          
    int target_ = -1;            
    float drag_start_main_ = 0;  
    float drag_offset_ = 0;      
    ValueAnimation settle_{0.0f};   
    ValueAnimation glow_{0.0f};     
    int glow_index_ = -1;           
};
 
}  // namespace pulp::view