IO.Github.Hcoona.Pngcs 1.2.1

.NET 8.0 .NET Standard 2.0

dotnet add package IO.Github.Hcoona.Pngcs --version 1.2.1

NuGet\Install-Package IO.Github.Hcoona.Pngcs -Version 1.2.1

This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.

<PackageReference Include="IO.Github.Hcoona.Pngcs" Version="1.2.1" />

For projects that support PackageReference, copy this XML node into the project file to reference the package.

<PackageVersion Include="IO.Github.Hcoona.Pngcs" Version="1.2.1" />
                    

                            Directory.Packages.props

<PackageReference Include="IO.Github.Hcoona.Pngcs" />
                    

                            Project file

For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.

paket add IO.Github.Hcoona.Pngcs --version 1.2.1

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

#r "nuget: IO.Github.Hcoona.Pngcs, 1.2.1"

#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.

#:package IO.Github.Hcoona.Pngcs@1.2.1

#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.

#addin nuget:?package=IO.Github.Hcoona.Pngcs&version=1.2.1
                    

                            Install as a Cake Addin

#tool nuget:?package=IO.Github.Hcoona.Pngcs&version=1.2.1
                    

                            Install as a Cake Tool

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

PNGCS

A small library to read/write huge PNG files in C#.

Overview

PngCs is a C# library to read/write PNG images.

It provides a simple API for progressive (sequential line-oriented) reading and writing. It's specially suitable for huge images, which one does not want to load fully in memory.

Installation

Install the NuGet package:

dotnet add package IO.Github.Hcoona.Pngcs

Or via Package Manager Console:

Install-Package IO.Github.Hcoona.Pngcs

Features

Modern .NET support: Multi-targeting for netstandard2.0, netstandard2.1, net8.0, and net9.0
Native AOT compatibility: Full support for Native Ahead-of-Time compilation
Supports all PNG spec color models and bitdepths:
- RGB8/RGB16/RGBA8/RGBA16
- G8/4/2/1
- GA8/4/2/1
- PAL8/4/2/1
All filters/compression settings
Support for Chunks (metadata)
API Compatibility: API aligned with Hjg.Pngcs v1.1.4. See CompatibilitySuppressions.xml for details.
Note: Does not support interlaced images

Origin

This is a port of the PngJ library (Java). The API, documentation and samples from PNGJ apply also to this PngCs library: http://code.google.com/p/pngj/wiki/Overview

History

See ChangeLog.md

Authors

Hernan J Gonzalez - hgonzalez@gmail.com - Stack Overflow Profile - The original author.
Shuai Zhang - zhangshuai.ustc@gmail.com - Current maintainer.

License

This project is licensed under the GNU General Public License v3.0 or later (GPL v3+). See LICENSE.GPL.txt for details.

Portions of the code are derived from an open source project originally licensed under the Apache License, Version 2.0 by Hernán J. González. The original copyright and license notice are preserved in accordance with the Apache License.

For more information, see the files:

LICENSE.GPL.txt (GPL v3+)
LICENSE.APACHE.txt (Apache 2.0)

Product	Compatible and additional computed target framework versions.
.NET	net5.0 was computed. net5.0-windows was computed. net6.0 was computed. net6.0-android was computed. net6.0-ios was computed. net6.0-maccatalyst was computed. net6.0-macos was computed. net6.0-tvos was computed. net6.0-windows was computed. net7.0 was computed. net7.0-android was computed. net7.0-ios was computed. net7.0-maccatalyst was computed. net7.0-macos was computed. net7.0-tvos was computed. net7.0-windows was computed. net8.0 is compatible. net8.0-android was computed. net8.0-browser was computed. net8.0-ios was computed. net8.0-maccatalyst was computed. net8.0-macos was computed. net8.0-tvos was computed. net8.0-windows was computed. net9.0 is compatible. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 was computed. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed.
.NET Core	netcoreapp2.0 was computed. netcoreapp2.1 was computed. netcoreapp2.2 was computed. netcoreapp3.0 was computed. netcoreapp3.1 was computed.
.NET Standard	netstandard2.0 is compatible. netstandard2.1 is compatible.
.NET Framework	net461 was computed. net462 was computed. net463 was computed. net47 was computed. net471 was computed. net472 was computed. net48 was computed. net481 was computed.
MonoAndroid	monoandroid was computed.
MonoMac	monomac was computed.
MonoTouch	monotouch was computed.
Tizen	tizen40 was computed. tizen60 was computed.
Xamarin.iOS	xamarinios was computed.
Xamarin.Mac	xamarinmac was computed.
Xamarin.TVOS	xamarintvos was computed.
Xamarin.WatchOS	xamarinwatchos was computed.

Compatible target framework(s)

Included target framework(s) (in package)

Learn more about Target Frameworks and .NET Standard.

.NETStandard 2.0
- No dependencies.
.NETStandard 2.1
- No dependencies.
net8.0
- No dependencies.
net9.0
- No dependencies.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version	Downloads	Last Updated
1.2.1	60	7/27/2025
1.2.0-beta.14	194	7/26/2025
1.2.0-beta.11	194	7/26/2025
1.2.0-beta.2	208	7/26/2025

# PngCs Changelog
A C# port of the PNG Java library.
## Version History on GitHub
Change logs for <https://github.com/hcoona/pngcs>.
### Version 1.2.1 (July 27, 2025)
- **Modern .NET support**: Multi-targeting for `netstandard2.0`, `netstandard2.1`, `net8.0`, and `net9.0`
- **Native AOT compatibility**: Full support for Native Ahead-of-Time compilation
- **NuGet package availability**: Official NuGet package with assembly name `Hjg.Pngcs`
- **Enhanced compression support**: Improved ZLib stream implementation
- Native `ZLibStream` support for .NET 8.0+ targets
- Unified compression stream architecture
- **Performance improvements**:
- Enhanced string operations with ordinal comparison
- Optimized dictionary lookups with `TryGetValue()` patterns
- Eliminated unnecessary array allocations
- **Bug fixes**:
- Fixed `PngChunkTIME.GetAsString()` format string issues
- Improved stream disposal to prevent resource leaks
- Fixed ThreadStatic field initialization problems
- **Breaking changes**:
- Assembly renamed from `pngcs` to `Hjg.Pngcs`
- Consolidated ZLib stream implementations (removed separate `ZlibInputStreamMs` and `ZlibOutputStreamMs` classes)
- Updated to GPL-3.0+ licensing
## Version History on Google Code
Change logs for <http://code.google.com/p/pngcs/>.
### Version 1.1.4 (December 15, 2012)
- **Dual targeting support**: .NET 4.5 with CLR `DeflateStream` (with custom Zlib wrapper) and older versions with SharpZipLib (requires additional DLL)
- New `Zlib` namespace/folder structure
- Decoupled compression implementation from SharpZipLib/.NET CLR
- Custom implementations of CRC32 and Adler checksums
- **Bug fixes**:
- Fixed bad namespace in internal `PngInterlacer`
- Replaced CRC test in `PngReader` with Adler32
### Version 1.1.3 (December 8, 2012)
- **Interlaced PNG support**: Full reading support for interlaced images
- **Enhanced sample storage**: Read/write operations now support both `INT` and `BYTE` for sample storage
- `ImageLine` includes `sampleType` with dual buffers: `Scanline` (integer) and `ScanlineB` (byte)
- New type-specific methods: `ReadRowInt`/`ReadRowByte`, `WriteRowInt`/`WriteRowByte`
- **Packed format support**: Bit depths 1-2-4 can be unpacked on-the-fly during read/write operations (see `PngReader.SetUnpackedMode()`)
- **Improved PngReader**:
- `ReadRow` can skip rows efficiently (`getRow` is now deprecated)
- More efficient decoding (only processes necessary data)
- New batch operations: `ReadRows`/`WriteRows` returning `ImageLines` object
- `PngReader.ReadSkippingAllRows` allows efficient pixel data skipping
- **Enhanced testing framework**:
- Added `crctest` and `PngReaderTest` for improved internal testing
- `PngSuiteTest` performs double-mirror comparison with original images (including interlaced)
- **API improvements**:
- `ImageLineHelper.Pal2rgb` (renamed, corrected, supports alpha with TRNS)
- Added `getMetadata().GetPalette()` and `getMetadata().CreateNewPalette()`
- Fixed textual chunk issues (null bytes, empty texts) with comprehensive testing
- **Code organization**: Extensive polishing and reorganization of test/sample code into unified project
### Version 1.0.96 (October 21, 2012)
- **API enhancement**: `SetMaxXXX()` methods now accept zero for unlimited operation (e.g., `PngReader.setMaxTotalBytesRead(0)`)
- **New sample**: Added `SampleCustomChunk` demonstrating custom chunk registration for read/write operations
- **Bug fixes**:
- Fixed `PNGChunkTIME` output format issues
- Fixed `PngWriter.init()` not being called internally when row number not provided
### Version 1.0.95 (August 14, 2012)
- **Enhanced security**: Defensive limits and tuning for `PngReader`
- New limits: `MaxTotalBytesRead` (200MB), `MaxBytesMetadata` (5MB), `SkipChunkMaxSize` (2MB)
- Added `SkipChunkIds` for "fdAT" chunks
- `PngChunkSkipped`: Truly skipped chunks (never loaded into memory)
- All skipped chunks represented as `PngChunkSkipped` in `ChunksLists`
- **Code improvements**:
- Removed `ParseChunkAndAddToList()`, added `ReadChunk()` method
- Added 'offset' property to chunks (informational)
- Updated `PngReader` offset to `long` type (supports >2GB files) with `MaxTotalBytesRead` validation
### Version 1.0.93 (June 23, 2012)
- **Non-sequential reading**: `PngReader.GetRow()` supports non-sequential access (useful for line skipping)
- **API update**: `PngReader.End()` no longer deprecated, now recommended
- **Bug fix**: Fixed `ImageLine.Pack()`/`ImageLine.Unpack()` buffer length requirements
- **New feature**: Added `PngWriter.ComputeCompressionRatio()`
### Version 1.0.92 (June 15, 2012)
- **License change**: Now released under Apache License
- **Standalone assembly**: Replaced external SharpZipLib with embedded `ICSharpCode.SharpZipLib.dll`
- **C# conventions**: Extensive refactoring to follow C# best practices
- **Breaking changes**: Signature modifications (especially casing) break backward compatibility
- Removed unnecessary LINQ imports and .NET 4.0 dependencies (now targets .NET 2.0)
- **Documentation**: Complete XML documentation for all classes and methods (`Pngcs.xml`)
- **Samples**: Reorganized and added new sample projects (e.g., `SampleCreateOrangeGradient`)
- **Documentation**: Added Doxygen documentation generation
### Version 1.0.91 (June 10, 2012)
- **Major reorganization**: Synchronized with Java port PngJ v0.91
- Complete chunk implementation and full PNG Test Suite support
- Public methods/properties now follow C# naming conventions
### Early Development
**September 22, 2011**: Feature parity achieved with current PngJ implementation. Testing, optimization, and validation pending.
**September 21, 2011**: Integrated SharpZipLib classes. Basic reading and writing functionality operational.
**January 2011**: Initial port from Java, assisted by j2cstranslator.sourceforge.net
---
## Credits
**Author**: Hernan J. Gonzalez
**Email**: <hgonzalez@gmail.com>
**Website**: <http://hjg.com.ar/>