selectable_text.hpp

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#pragma once
 
// SelectableText — the capability that lets a text-bearing widget take part in
// a selection that spans more than one widget.
//
// The shape follows the repo's "expose the pipeline, not just the endpoints"
// rule. Both `Label` and `TextEditor` already compute, during paint, the exact
// intermediate a selection needs: where each painted line sits and where every
// cluster boundary falls inside it. `TextEditor` kept that intermediate private
// in `LayoutSnapshot`; `Label` threw it away entirely. This header names that
// intermediate once, so the hit-test and rect arithmetic are written a single
// time instead of per widget.
//
// Offsets are UTF-8 BYTE offsets into `selectable_text()`, matching the units
// `TextEditor` already uses for its own selection and the units
// `text_accessibility.hpp` reports to assistive technology
// (`selection_start_utf8` / `selection_end_utf8`).
 
#include <pulp/view/geometry.hpp>
 
#include <string>
#include <string_view>
#include <vector>
 
namespace pulp::view {
 
class View;

struct SelectableLine {
    int start_utf8 = 0; 
    int end_utf8 = 0;   
    float top = 0.0f;
    float height = 0.0f;
    std::vector<float> x_offsets;
    std::vector<int> byte_offsets;
};

struct SelectableLayout {
    bool measured = false;
    std::vector<SelectableLine> lines;
};

class SelectableText {
  public:
    virtual ~SelectableText() = default;

    virtual std::string_view selectable_text() const = 0;

    virtual SelectableLayout selectable_layout() const = 0;

    virtual void set_selection_highlight(int start_utf8, int end_utf8) = 0;

    virtual bool selection_highlight(int& start_utf8, int& end_utf8) const = 0;

    virtual View* selectable_view() = 0;
    const View* selectable_view() const {
        return const_cast<SelectableText*>(this)->selectable_view();
    }
};

View* enclosing_text_selection_region(View& from);

int selectable_index_at_point(const SelectableLayout& layout, Point local);

std::vector<Rect> selectable_rects_for_range(const SelectableLayout& layout, int start_utf8,
                                             int end_utf8);

int selectable_first_index(const SelectableLayout& layout);
int selectable_last_index(const SelectableLayout& layout);
 
} // namespace pulp::view