Centralized pixel encoding/decoding utilities for framebuffers. More...
#include "epaper/color/color.hpp"#include "epaper/core/types.hpp"#include "epaper/drivers/driver.hpp"#include <array>#include <cstddef>#include <cstdint>#include <span>
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Namespaces | |
| namespace | epaper |
| namespace | epaper::pixel_constants |
Functions | |
| constexpr auto | epaper::spectra6_color_to_value (Color color) noexcept -> std::uint8_t |
| Convert a Color to its 3-bit Spectra6 value. | |
| constexpr auto | epaper::spectra6_value_to_color (std::uint8_t value) noexcept -> Color |
| Convert a 3-bit Spectra6 value to Color. | |
| constexpr auto | epaper::color_to_rgb (Color color) noexcept -> RGB |
| Convert a Color enum to RGB values. | |
| constexpr auto | epaper::rgb_to_grayscale (std::uint8_t r, std::uint8_t g, std::uint8_t b) noexcept -> std::uint8_t |
| Convert RGB values to grayscale using standard luminance formula. | |
| constexpr auto | epaper::rgb_to_color_bw (std::uint8_t r, std::uint8_t g, std::uint8_t b) noexcept -> Color |
| Convert RGB to Color for black/white mode. | |
| constexpr auto | epaper::rgb_to_color_grayscale4 (std::uint8_t r, std::uint8_t g, std::uint8_t b) noexcept -> Color |
| Convert RGB to Color for 4-level grayscale mode. | |
| constexpr auto | epaper::rgb_to_color (DisplayMode mode, std::uint8_t r, std::uint8_t g, std::uint8_t b) noexcept -> Color |
| Convert RGB to Color based on display mode. | |
| constexpr auto | epaper::calculate_bw_position (std::size_t width, std::size_t x, std::size_t y) noexcept -> std::pair< std::size_t, std::uint8_t > |
| Calculate byte index and bit mask for B/W mode pixel. | |
| constexpr auto | epaper::calculate_gray_position (std::size_t width, std::size_t x, std::size_t y) noexcept -> std::pair< std::size_t, std::uint8_t > |
| Calculate byte index and pixel shift for Grayscale4 mode pixel. | |
| constexpr auto | epaper::calculate_spectra6_position (std::size_t width, std::size_t x, std::size_t y) noexcept -> std::pair< std::size_t, std::size_t > |
| Calculate byte index and bit offset for Spectra6 (3-bit) mode pixel. | |
| auto | epaper::get_pixel_bw (std::span< const std::byte > buffer, std::size_t width, std::size_t x, std::size_t y) noexcept -> Color |
| Read a pixel from a B/W mode buffer. | |
| auto | epaper::get_pixel_grayscale4 (std::span< const std::byte > buffer, std::size_t width, std::size_t x, std::size_t y) noexcept -> Color |
| Read a pixel from a Grayscale4 mode buffer. | |
| auto | epaper::get_pixel_bwr_bwy (std::span< const std::byte > buffer, std::size_t width, std::size_t height, std::size_t x, std::size_t y, bool is_bwr) noexcept -> Color |
| Read a pixel from a BWR or BWY mode buffer. | |
| auto | epaper::get_pixel_spectra6 (std::span< const std::byte > buffer, std::size_t width, std::size_t x, std::size_t y) noexcept -> Color |
| Read a pixel from a Spectra6 mode buffer. | |
| auto | epaper::get_pixel_from_buffer (DisplayMode mode, std::span< const std::byte > buffer, std::size_t width, std::size_t height, std::size_t x, std::size_t y) noexcept -> Color |
| Read a pixel from a buffer based on display mode. | |
| auto | epaper::set_pixel_bw (std::span< std::byte > buffer, std::size_t width, std::size_t x, std::size_t y, Color color) noexcept -> void |
| Write a pixel to a B/W mode buffer. | |
| auto | epaper::set_pixel_grayscale4 (std::span< std::byte > buffer, std::size_t width, std::size_t x, std::size_t y, Color color) noexcept -> void |
| Write a pixel to a Grayscale4 mode buffer. | |
| auto | epaper::set_pixel_bwr_bwy (std::span< std::byte > buffer, std::size_t width, std::size_t height, std::size_t x, std::size_t y, Color color, bool is_bwr) noexcept -> void |
| Write a pixel to a BWR or BWY mode buffer. | |
| auto | epaper::set_pixel_spectra6 (std::span< std::byte > buffer, std::size_t width, std::size_t x, std::size_t y, Color color) noexcept -> void |
| Write a pixel to a Spectra6 mode buffer. | |
| auto | epaper::set_pixel_in_buffer (DisplayMode mode, std::span< std::byte > buffer, std::size_t width, std::size_t height, std::size_t x, std::size_t y, Color color) noexcept -> void |
| Write a pixel to a buffer based on display mode. | |
Variables | |
| constexpr std::array< Color, 8 > | epaper::SPECTRA6_VALUE_TO_COLOR |
| Mapping from 3-bit Spectra6 value to Color enum. | |
Black/White Mode Constants | |
| constexpr std::uint8_t | epaper::pixel_constants::BW_PIXELS_PER_BYTE = 8 |
| constexpr std::uint8_t | epaper::pixel_constants::BW_MSB_MASK = 0x80 |
Grayscale4 Mode Constants | |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_PIXELS_PER_BYTE = 4 |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_BITS_PER_PIXEL = 2 |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_PIXEL_MASK = 0xC0 |
Spectra6 Mode Constants | |
| constexpr std::uint8_t | epaper::pixel_constants::SPECTRA6_BITS_PER_PIXEL = 3 |
| constexpr std::uint8_t | epaper::pixel_constants::SPECTRA6_COLOR_MASK = 0x07 |
Grayscale Thresholds (for RGB conversion) | |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_THRESHOLD_WHITE = 192 |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_THRESHOLD_LIGHT = 128 |
| constexpr std::uint8_t | epaper::pixel_constants::GRAY_THRESHOLD_DARK = 64 |
Detailed Description
Centralized pixel encoding/decoding utilities for framebuffers.
Provides all the bit manipulation logic for reading and writing pixels in various display modes. This eliminates duplication between Display and MockDriver while documenting the exact framebuffer format for each mode.
Supported Display Modes:
- BlackWhite: 1 bit per pixel, MSB-first, 8 pixels/byte
- Grayscale4: 2 bits per pixel, 4 levels (White/Gray1/Gray2/Black), 4 pixels/byte
- BWR/BWY: Dual-plane, 1 bit per pixel per plane (BW + Color), active-low color
- Spectra6: 3 bits per pixel, 6 colors, cross-byte packing
Design Principles:
- Pure functions: No side effects, all constexpr where possible
- Type safety: std::span<std::byte> instead of raw pointers
- Bounds checking: All functions validate buffer sizes
- Integer-only: No floating point in pixel operations
- Fallback values: Return safe defaults (White) on error
Bit Layout Examples:
Black/White (1bpp MSB-first):
Byte: [p0 p1 p2 p3 p4 p5 p6 p7]
p0 = MSB (bit 7), p7 = LSB (bit 0)
1 = White, 0 = Black
Grayscale4 (2bpp):
Byte: [p0_hi p0_lo | p1_hi p1_lo | p2_hi p2_lo | p3_hi p3_lo]
00 = Black, 01 = Gray2, 10 = Gray1, 11 = White
BWR/BWY (dual-plane 1bpp):
Plane 0 (BW): [b0 b1 b2 ... ] (1=White, 0=Black)
Plane 1 (Color): [c0 c1 c2 ... ] (0=Color, 1=Transparent) [active-low]
Color pixel = (BW=0, Color=0), White = (BW=1, Color=1)
Spectra6 (3bpp cross-byte):
3 pixels = 9 bits = 1 byte + 1 bit:
[p0_b2 p0_b1 p0_b0 | p1_b2 p1_b1 p1_b0 | p2_b2 p2_b1 p2_b0 ...]
Values: 0=Black, 1=White, 2=Red, 3=Yellow, 4=Blue, 5=Green
- See also
- DisplayMode, Color, MonoFramebuffer, MultiPlaneFramebuffer
