[video_player] [WIP] Add web implementation

[cbenhagen]

Description

This is adding a web plugin for video_player using HtmlElementView and a generated plugin registrant.

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[MateusAmin]

Thanks for working on this @cbenhagen :D

[amirh]

We can't land this before next stable release as the plugin won't compile with the stable tool.

[amirh]

This should be implemented as a federated package (see: https://flutter.dev/go/federated-plugins).

I think this plugin needs a refactoring to have a Dart platform interface before adding the web implementation.

cc @hterkelsen

[cbenhagen]

@amirh / @hterkelsen I feel a bit lost adding that platform interface and especially in adding the needed tests. Would you be able to provide some guidance / mentoring?

[harryterkelsen]

Hi Ben, I'm happy to help! To get you started, you can take a look at the changes I made to url_launcher to add a platform interface:

• Adding the platform interface: https://github.com/flutter/plugins/pull/2217/files
• Using the interface in package:url_launcher: https://github.com/flutter/plugins/pull/2228/files
• Updating url_launcher_web to implement the platform interface: https://github.com/flutter/plugins/pull/2237/files

Please don't hesitate to ask if you have any questions

[cbenhagen]

@hterkelsen I used your changes as a template and opened #2273 and #2276.

Is there an advantage in using method channels for the web plugins? Or should I just implement a WebVideoPlayer which does not use them?

[cbenhagen]

Closing in favor of #2279