Error compiling for HoloLens

[motionsmith]

Hello,

I'm trying to use zxing.unity.dll on the HoloLens. I'm so close.

When building, I'm getting the following error, related to System.ComponentModel.BrowsableAttribute:
Reference rewriter: Error: type System.ComponentModel.BrowsableAttribute doesn't exist in target framework.

There are about 4 of these errors that reference this namespace in various places. I saw a video online of someone who was successful in deploying ZXing to Unity/HoloLens, but they didn't mention this issue. I'm not sure if it's some version difference. But anyway, here are some specs:

• Unity 5.5.1f1
• ZXing.Net (not sure the version, but recent as of today)
• Visual Studio 2015

Thank you!
Eric

[motionsmith]

Following up with more info, it seems to be related to some post process that HoloToolkit is doing... so not sure if this falls under anyone's jurisdiction. The call stack reveals:

PostProcessWinRT:RunReferenceRewriter() (at C:/buildslave/unity/build/PlatformDependent/WinRT/SharedSources/CSharp/PostProcessWinRT.cs:560) PostProcessWinRT:Process() (at C:/buildslave/unity/build/PlatformDependent/WinRT/SharedSources/CSharp/PostProcessWinRT.cs:127) UnityEditor.BuildPipeline:BuildPlayer(String[], String, BuildTarget, BuildOptions) HoloToolkit.Unity.BuildSLNUtilities:PerformBuild(BuildInfo) (at Assets/HoloToolkit/Build/Editor/BuildSLNUtilities.cs:219) HoloToolkit.Unity.BuildDeployTools:BuildSLN(String, Boolean) (at Assets/HoloToolkit/Build/Editor/BuildDeployTools.cs:30)

[micjahn]

I think the ZXing.Unity build isn't perfect. But I can't test it myself. I looked a little bit around in the internet
and found some posts which describe solutions for the same or a similar problem.
Perhaps that would help you:
https://forums.hololens.com/discussion/3263/zxing-unity-barcode-dll-issue
https://forums.hololens.com/discussion/2337/has-anyone-been-able-to-successfully-use-zxing-in-their-hololens-app
https://mtaulty.com/2016/12/28/windows-10-uwp-qr-code-scanning-with-zxing-and-hololens/
It would be great if someone with more experience on unity can give me some hints (or a pull request) with changes in the zxing codebase to get it running out of the box.

[motionsmith]

Thanks for the links. I think there are a lot of options to try. My current hypothesis is that there is an incompatibility with the HoloToolkit. But I still have a lot of options to try. I'll check in if I make any progress today.

[motionsmith]

@micjahn I found this user who has the same problem.
https://forum.unity3d.com/threads/zxing-net-and-browsableattribute.429933/

We need to remove references to the System.ComponentModel.BrowsableAttribute class/namespace. Do you think that the Unity build of ZXing.Net can go without this namespace? How hard would it be to remove?

(BTW, the other option mentioned in the thread produces a litany of other errors due to IL2CPP incompatibilities. I think removing the BrowsableAttribute references is lower friction).

I tried to build ZXing.Net right out of the box but got a bunch of errors. I'm not sure if it's a VS config issue, or what the problem is. If you are able to walk me through how to build ZXing.Net, maybe I can work to remove BrowsableAttribute. If you know how to safely remove reference to it in the Unity build of ZXing, that would be even better. :)

[motionsmith]

Update: I think that we need to wrap the [Browsable] attributes in #if !UNITY. I can't compile the Unity build to find out (see my other thread), but I've copied the entire .NET 3.5 project into Unity and have been slowly combing through errors. That browsable attribute is one of the pieces that HoloLens doesn't like.

[micjahn]

I don't understand why other users get it running with the published assembly.
Anyway, ZXing.Net should be buildable out of the box. If you use VS 2012 or newer you have to disable
parallel builds because the different projects stay in the same directory and using the same obj directory.
I will remove the Browsable attribute next time and build a new binary. Hopefully this week.

[motionsmith]

@micjahn It does work on Unity, just not a UWP application built by Unity (published as a Windows Store App). The error comes when Unity compiles for UWP, specifically.

So I guess the directive would be #if !UNITY && UWP. I'd be happy to pursue making this pull request if you can help me with my problem building the Unity-specific DLL.

[micjahn]

I made a special build without the Browsable attribute.
Please try it with your UWP app.
https://www.dropbox.com/s/9tzhrnvqco6csf1/zxing.unity.dll?dl=0

[motionsmith]

Thanks! I'm going to try this asap.

[micjahn]

Next version of ZXing.Net will included binaries for unity without the Browseable attribute. Source code changes are already within the repository.