accessibility.hpp

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#pragma once
 
// Accessibility interfaces for platform screen reader integration.
// Provides ValueInterface, TextInterface, TableInterface, CellInterface
// that can be attached to Views for accessibility provider implementation.
 
#include <string>
#include <string_view>
#include <functional>
#include <optional>
#include <vector>
 
namespace pulp::view {

class AccessibilityValueInterface {
public:
    // Out-of-line in src/accessibility.cpp so the vtable + typeinfo
    // anchors there — required for dynamic_cast on Android NDK builds
    // that link with -Wl,--no-undefined.
    virtual ~AccessibilityValueInterface();

    virtual double get_current_value() const = 0;

    virtual void set_current_value(double value) = 0;

    virtual double get_minimum_value() const = 0;

    virtual double get_maximum_value() const = 0;

    virtual double get_step_size() const { return (get_maximum_value() - get_minimum_value()) / 100.0; }

    virtual std::string get_value_string() const;
};

class AccessibilityTextInterface {
public:
    virtual ~AccessibilityTextInterface();

    virtual std::string get_text() const = 0;

    virtual void set_text(std::string_view text) = 0;

    virtual std::pair<int, int> get_selection() const { return {0, 0}; }

    virtual void set_selection(int start, int end) { (void)start; (void)end; }

    virtual bool is_editable() const { return false; }

    virtual int get_character_count() const {
        return static_cast<int>(get_text().size());
    }

    virtual std::string get_text_range(int start, int end) const {
        auto text = get_text();
        if (start < 0) start = 0;
        if (end > static_cast<int>(text.size())) end = static_cast<int>(text.size());
        if (start >= end) return "";
        return text.substr(static_cast<size_t>(start), static_cast<size_t>(end - start));
    }
};

class AccessibilityTableInterface {
public:
    virtual ~AccessibilityTableInterface();

    virtual int get_row_count() const = 0;

    virtual int get_column_count() const = 0;

    virtual std::string get_column_header(int column) const = 0;

    virtual int get_selected_row() const { return -1; }

    virtual void select_row(int row) { (void)row; }

    virtual bool supports_multi_selection() const { return false; }

    virtual std::vector<int> get_selected_rows() const {
        int row = get_selected_row();
        return row >= 0 ? std::vector<int>{row} : std::vector<int>{};
    }
};

class AccessibilityCellInterface {
public:
    virtual ~AccessibilityCellInterface();

    virtual std::string get_cell_text(int row, int column) const = 0;

    virtual bool is_cell_editable(int row, int column) const { (void)row; (void)column; return false; }

    virtual std::pair<int, int> get_cell_span(int row, int column) const {
        (void)row; (void)column;
        return {1, 1};
    }
};
 
// ── Value resolution ────────────────────────────────────────────────────
 
class View;

enum class AccessToggleState { unset, off, on, mixed };

AccessToggleState accessibility_toggle_state(const View& v);

std::string accessibility_toggle_state_string(const View& v);

std::string accessibility_value_string(const View& v);

bool has_accessibility_value(const View& v);

struct AccessibilityInterfaceSet {
    bool value = false;
    bool text = false;
};
AccessibilityInterfaceSet accessibility_interfaces(const View& v);

std::string accessibility_text_content(const View& v);

bool accessibility_text_editable(const View& v);

bool is_accessibility_element(const View& v);
 
// ── Live-region announcements ───────────────────────────────────────────

enum class AnnouncementPriority {
    Polite,
    Assertive,
};

void announce_accessibility(std::string_view text,
                            AnnouncementPriority priority = AnnouncementPriority::Polite);

using AnnouncementSink =
    std::function<void(std::string_view text, AnnouncementPriority)>;
void set_announcement_sink(AnnouncementSink sink);
 
}  // namespace pulp::view