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https://github.com/randy408/libspng

Simple, modern libpng alternative
https://github.com/randy408/libspng

c c99 cmake codec decoding encoder libpng meson optimized oss-fuzz png png-decoder png-encoder spng

Last synced: 2 days ago
JSON representation

Simple, modern libpng alternative

Host: GitHub
URL: https://github.com/randy408/libspng
Owner: randy408
License: bsd-2-clause
Created: 2018-03-28T10:39:20.000Z (almost 7 years ago)
Default Branch: master
Last Pushed: 2024-06-15T13:27:26.000Z (7 months ago)
Last Synced: 2025-01-02T03:10:24.566Z (10 days ago)
Topics: c, c99, cmake, codec, decoding, encoder, libpng, meson, optimized, oss-fuzz, png, png-decoder, png-encoder, spng
Language: C
Homepage: https://libspng.org
Size: 942 KB
Stars: 755
Watchers: 29
Forks: 74
Open Issues: 75
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE
- Security: SECURITY.md

Awesome Lists containing this project

awesome-game-engine-dev - Libspng - Simple, modern libpng alternative. (Libraries / C)

README

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# libspng

lib**spng** (**s**imple **png**) is a C library for reading and writing Portable Network Graphics (PNG)

format files with a focus on security and ease of use.

libspng is an alternative to libpng, the projects are separate and the APIs are

not compatible.

## Motivation

The goal is to provide a fast PNG library with a simpler API than [libpng](https://github.com/glennrp/libpng/blob/libpng16/png.h),

it outperforms the reference implementation in common use cases.

## Performance

![](https://libspng.org/perfx86.png)

## Features

| Feature                              |  spng   | libpng             | stb_image | lodepng |

|--------------------------------------|---------|--------------------|-----------|---------|

| Decode from stream                   | ✅      |  ✅               | ✅       | ❌      |

| Gamma correction                     | ✅      |  ✅               | ❌       | ❌      |

| No known security bugs^[1] | ✅      |  ✅               | ❌       | ✅      |

| Progressive image read               | ✅      |  ✅               | ❌       | ❌      |

| Parses all standard chunks           | ✅      |  ✅               | ❌       | ❌      |

| Doesn't require zlib^[2]   | ✅      |  ❌               | ✅       | ✅      |

| Encoding                             | ✅      |  ✅               | ✅       | ✅      |

| Animated PNG                         | Planned  |  ✅^[3] | ❌       | ❌      |

^[1] The project is fuzz tested on [OSS-Fuzz](https://github.com/google/oss-fuzz) and vulnerabilities are fixed before they become public.

^[2] Building with miniz is [supported](docs/build.md#miniz).

^[3] With a 3rd party patch

## Getting spng

Download the [latest release](https://libspng.org/download) and include `spng.c/spng.h` in your project,

you can also build with CMake or Meson, refer to the [documentation](docs/build.md) for details.

## Usage

```c

#include 

/* Create a decoder context */

spng_ctx *ctx = spng_ctx_new(0);

/* Set an input buffer */

spng_set_png_buffer(ctx, buf, buf_size);

/* Determine output image size */

spng_decoded_image_size(ctx, SPNG_FMT_RGBA8, &out_size);

/* Decode to 8-bit RGBA */

spng_decode_image(ctx, out, out_size, SPNG_FMT_RGBA8, 0);

/* Free context memory */

spng_ctx_free(ctx);

/* Creating an encoder context requires a flag */

spng_ctx *enc = spng_ctx_new(SPNG_CTX_ENCODER);

/* Encode to internal buffer managed by the library */

spng_set_option(enc, SPNG_ENCODE_TO_BUFFER, 1);

/* Specify image dimensions, PNG format */

struct spng_ihdr ihdr =

{

    .width = width,

    .height = height,

    .bit_depth = 8,

    .color_type = SPNG_COLOR_TYPE_TRUECOLOR_ALPHA

};

/* Image will be encoded according to ihdr.color_type, .bit_depth */

spng_set_ihdr(enc, &ihdr);

/* SPNG_FMT_PNG is a special value that matches the format in ihdr,

   SPNG_ENCODE_FINALIZE will finalize the PNG with the end-of-file marker */

spng_encode_image(enc, image, image_size, SPNG_FMT_PNG, SPNG_ENCODE_FINALIZE);

/* PNG is written to an internal buffer by default */

void *png = spng_get_png_buffer(enc, &png_size, &error);

/* User owns the buffer after a successful call */

free(png);

/* Free context memory */

spng_ctx_free(enc);

```

See [example.c](examples/example.c).

## License

Code is licensed under the BSD 2-clause "Simplified" License.

The project contains optimizations and test images from libpng, these are licensed under the

[PNG Reference Library License version 2](http://www.libpng.org/pub/png/src/libpng-LICENSE.txt).

## Security & Testing

Code is written according to the rules of the

[CERT C Coding Standard](https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard).

All integer arithmetic is checked for overflow and all error conditions are handled gracefully.

The library is continuously fuzzed by [OSS-Fuzz](https://github.com/google/oss-fuzz),

code is also scanned with Clang Static Analyzer, Coverity Scan and PVS-Studio.

The test suite consists of over 1000 test cases,

175 [test images](http://www.schaik.com/pngsuite/) are decoded with all possible

output format and flag combinations and compared against libpng for [correctness](tests/README.md#Correctness).

## Versioning

Releases follow the [semantic versioning](https://semver.org/) scheme with additional guarantees:

* Releases from 0.4.0 to 0.8.x are stable

* If 1.0.0 will introduce breaking changes then 0.8.x will be maintained as a separate stable branch

Currently 1.0.0 is planned to be [compatible](https://github.com/randy408/libspng/issues/3).

## Documentation

Online documentation is available at [libspng.org/docs](https://libspng.org/docs).

## Known Issues

* Decoding to `SPNG_FMT_G8`, `SPNG_FMT_GA8` and `SPNG_FMT_GA16` output formats is not supported

 for all PNG color type and bit depth combinations, see documentation for details.

* Gamma correction is not implemented for `SPNG_FMT_PNG`, `SPNG_FMT_G8`, `SPNG_FMT_GA8`

 and `SPNG_FMT_GA16` output formats.

## Supporting spng

You can sponsor development through [OpenCollective](https://opencollective.com/libspng/), funds will be used for maintenance and further development according to the [roadmap](https://github.com/randy408/libspng/milestones).

### OpenCollective backers

#### Individuals



#### Organizations

Support this project with your organization. Your logo will show up here with a link to your website. [[Contribute](https://opencollective.com/libspng/contribute)]