Imagesharp: PNGEncoder does not write EXIF data

[Inumedia]

Prerequisites

• [x] I have written a descriptive issue title
• [x] I have verified that I am running the latest version of ImageSharp
• [x] I have verified if the problem exist in both DEBUG and RELEASE mode
• [x] I have searched open and closed issues to ensure it has not already been reported

Description

PNGEncoder does not seem to write the EXIF chunk as expected, while this seems to be intentional I'd recommend adding the ability to turn this on or an API for writing it yourself as a user.

Steps to Reproduce

• Encode PNG
• View PNG's EXIF data using any online EXIF tool

System Configuration

Windows 10 / .NET Core 2.0

• ImageSharp version: 1.0.0-beta0004
• Other ImageSharp packages and versions:
• Environment (Operating system, version and so on): Windows 10
• .NET Framework version: .NET Core 2.0
• Additional information:

[JimBobSquarePants]

Implementation specification notes.

http://ftp-osl.osuosl.org/pub/libpng/documents/pngext-1.5.0.html#C.eXIf

[brianpopow]

i have started to work on this.

As the png EXIF is basically defined as: "it should be the same as in JPG", i was able to use the existing ExifReader. Encoding and Decoding seems to work in my first attempt.

[JimBobSquarePants]

@brianpopow Ah fantastic, Thanks!

Yeah our EXIF API is nicely decoupled from the individual image formats so once you have reading/writing the chunk identifiers it should work immediately.