How to engine map in the developed source code in Flutter? (Android) - flutter

I have recently developed an Android App with Google's Flutter Framework. When taking a deeper look into what is going on when the app compiles I saw that flutter builds four blobs of data (non-ELF binary). How does the Flutter engine load that code (my developed source code if I am not mistaken) at runtime?
I searched the Flutter engine documentation for more information, but the only thing I could find is, that the engine "maps in" those blobs (called snapshots);
Source: https://github.com/flutter/flutter/wiki/Flutter-engine-operation-in-AOT-Mode)
How does that "mapping in" actually work? I understand, that the flutter engine can communicate with the underlying android runner app via JNI, but how does it load my developed Dart Code?
I tried to read the flutter engine source code, but it's written in C++ and I'm rather unfamiliar with that.
So if anyone has a deeper insight into the startup process of a flutter app for android any new information or suggestions would be appreciated, I can't seem to be able to wrap my head around what's going on with those binary data files.

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Creating an audio visualizer in Flutter for web

I'm currently trying to create an audioplayer in Flutter Web, which is also able to visualize the bytefrequencydata. I already built this app in Angular but i just don't know how to access the data via audiocontext like in js.
I searched many libraries but none seems to provide the option to create an analyser node,
There is the standard dart:web_audio lib, but I can't use that in Flutter.
I am getting really desperate since there is also not a single tutorial to find which shows how to build such an app for flutter web, or at least I can't seem to find one.
The app only needs to run for flutter web.
A little help to get me on the right tracks would be much appreciated.

Flutter. Is it possible to see the generated native code for the specific platform?

I am currently working with cross-platform frameworks like Flutter, while I was studying the docs and architecture I was wondering if it is possible to see the compiled native code?
In the figure, you can see the Flutter architecture. As I understand it, the written Dart code is generated into a platform specific native code. Is it possible to view this code? I would find it very interesting to check the code quality of the generated code.

Do iOS and Android Flutter widgets also work on Flutter Web(PWA)

I'm interested in using Flutter primarily for my startup MVP on Web and possibly Android. I see the flutter community has made a lot of widgets but a lot of them are tagged iOS or Android. Since Futter is all about using one codebase is it wrong to assume that these widgets would work on web too? I imagine the setup would be different but similar with a Flutter web app as opposed to a Flutter Android app.
I couldn't find a whole lot about this on the Flutter site. I also know that web is still beta but by the time I'm done with the MVP it'll probably be at stable release or close enough.
Well... It depends. If the widget has some sort of native code the answer is no. In Flutter there are two type of packages: the "normal" package, and the plugin.
The packages are made only of dart code, so there are no bounds to native, and you can use everywhere dart (and Flutter) can run.
The plugins are packages with native code and you can use only on the platform supported by that plugin.
For example the package provider, it's a package, and you can use in every supported platform where dart (and Flutter) can run. But url_launcher, it's a plugin, so you can run only on Android, iOS, and web, but for example on desktop, it will no work.
If the package if you found it's only a widget, you should be able to use on the web.
TLDR: No,a PWA it's a web app, so it can't run Android or iOS specific code.

Is there any built in flutter library for 2D bar-code scanner?

I am developing a mobile application with Flutter framework and I want to scan bill bar-code and extract its code, so I need a bar-code scanner library for my app. Actually I've googled and found some libraries and SDKs, but they are not written in Dart and I have to import and implement them separately for Android and iOS directories, also it has lots of effort for me to import native codes to a Flutter project. Now I have following questions:
Is there any Dart written and Flutter compatible package, library, SDk, API or ... to use in Flutter project?
Hasn't Google made Flutter version of its ML-KIT or Google-Vision SDKs for its own multi platform framework?
Thanks in advance for helping me.
There are no direct flutter widgets available which supports Barcode reading as of now.
Anyway you can use firebase_ml_vision plugin which pretty straight forward and easy to integrate.
https://pub.dartlang.org/packages/firebase_ml_vision
There is, but I haven't ever used it myself. Just searched it on here: https://pub.dartlang.org/flutter
https://pub.dartlang.org/packages/barcode_scan or maybe this https://pub.dartlang.org/packages/barcode_flutter

How to get a working QR code scanner for Flutter web?

I’m kind of expecting the impossible, but asking anyway to ensure I’ve not missed out on any great ideas.
I’ve tried a couple of Flutter QR code scanner libraries, but as I was kind of expecting, none of those would run when I used the web beta support in Chrome for instance.
My question is, is there a Flutter QR code scanner library that works for iOS, Android and Web?
If not, is there a way to write this in Flutter for Web specifically?
There was one Stack Overflow question of running a QR scanner JavaScript library inside a WebView and trying to run a Web version which the post indicated faced issues with camera streaming. Is this a possible approach that would translate to Web?
Is there any other way to have a QR code scanner in Flutter to run in Web?
You could use an API like http://goqr.me/api/ in your flutter web project. You just have to use the read command on their api. I think it returns a response in either json or xml. If that isn't enough there are othe apis just search it till you find a cool one