capabilities.hpp File Reference

Compile-time driver capability traits system. More...

#include "epaper/drivers/driver.hpp"
#include <concepts>
#include <cstddef>

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Namespaces
namespace	epaper

Concepts
concept	epaper::DriverTraits
	Concept to check if a type is a valid driver with capabilities.

Functions
template<typename Driver > requires DriverTraits<Driver>
constexpr auto	epaper::supports_display_mode (DisplayMode mode) noexcept -> bool

Detailed Description

Compile-time driver capability traits system.

Provides template specialization-based mechanism for querying driver capabilities at compile time. Used for static validation, optimization, and feature detection.

Design Pattern:

Trait Class Pattern (Compile-Time Introspection)
├─ Specialization: Each driver specializes driver_traits<Driver>
├─ Constexpr Fields: All capabilities are compile-time constants
├─ Zero Runtime Cost: All queries resolved at compile time
└─ Validation: DriverTraits concept enforces complete specialization

Capabilities Provided:

• max_mode: Highest DisplayMode supported (e.g., DisplayMode::BWR)
• supports_grayscale: Can render 4-level grayscale
• supports_partial_refresh: Can update regions without full refresh
• supports_power_control: Can enter/exit sleep modes
• supports_wake_from_sleep: Can wake without full re-init
• max_width, max_height: Physical display dimensions

Specialization Template:

template <>
struct driver_traits<MyDriver> {
  static constexpr DisplayMode max_mode = DisplayMode::BWR;
  static constexpr bool supports_grayscale = true;
  static constexpr bool supports_partial_refresh = false;
  static constexpr bool supports_power_control = true;
  static constexpr bool supports_wake_from_sleep = true;
  static constexpr std::size_t max_width = 264;
  static constexpr std::size_t max_height = 176;
};

Usage Patterns:

// Compile-time capability check
if constexpr (driver_traits<EPD27>::supports_grayscale) {
  // Use Grayscale4 mode
}
 
// Static assertion for required features
static_assert(driver_traits<MyDriver>::supports_power_control,
              "This application requires sleep mode support");
 
// Mode validation
bool can_use_bwr = supports_display_mode<EPD27>(DisplayMode::BWR);

Mode Support Logic:

• BlackWhite: Always supported (baseline)
• Grayscale4: Requires supports_grayscale == true
• Color modes (BWR/BWY/Spectra6): Requires exact match with max_mode
• Rationale: Color modes are hardware-specific, not hierarchical

See also

Driver, DisplayMode, supports_display_mode()