Lightweight, bitonal image compression static C++ library that was designed with WASM-compatibility in mind. Built for The Gecko Project.

Gecko requires the following to build:

• CMake version 3.16 or above
• A compiler which supports C++ 20 features

First, clone the reposity. Gecko can be built and configured for a variety of different environments and build systems. To configure and build a x64 Release for Visual Studio 2022, run:

cmake -B out/build -S . -G "Visual Studio 17 2022" -A x64 && cmake --build out/build --config Release

Subsequent builds that don't require reconfiguring cmake can be simplified:

cmake --build out/build --config Release

Gecko uses GoogleTest framework, and integrates with ctest to run tests in a configuration-agnostic way. To execute all tests for a Release build, run:

ctest --test-dir build -C Release

If you've configured your project for Visual Studio, the tests can alternatively be discovered and run via the Test Explorer.

For now, Gecko's compression library currently only supports encoding from / to 3-channel bitmaps. More specifically, it only supports encoding to uncompressed, positive-height, 24bpp .bmp files that follow the BITMAPINFOHEADER header format. Indexed-color bitmaps (with color palettes) are not supported.

Although these limitations may seem overly strict, Gecko is only really designed to be used by, well, Gecko.

#include <optional>
#include <cstddef>
#include <vector>
#include "CompressedBitonal.h"
#include "UncompressedBitonal.h"
using namespace Gecko::Compression;

...

std::vector<uint8_t> bmpBytes{}; // Load uncompressed bytes

std::optional<UncompressedBitonal> uncompressed;
std::optional<CompressedBitonal> compressed;
std::optional<std::vector<uint8_t>> compressedBytes;

uncompressed = UncompressedBitonal::TryReadFromBuffer(bmpBytes, UncompressedBitonal::StorageFormat::BMPStrict24);

if (uncompressed)
  compressed = Encoder::TryCompressBitonal(*uncompressed);

if (compressed)
  compressedBytes = CompressedBitonal::TryWriteToBuffer(*compressed, CompressedBitonal::StorageFormat::BDC);

if (compressedBytes)
  ; // Save compressed bytes