v1: Web Multi-View - embedding Flet web app into existing web page

[FeodorFitsner]

Summary by Human

before_main

A new before_main arg added to ft.run(). before_main is a hook that allows to reliable configure page-level event handlers before Flutter client starts sending events. before_main is a function that accepts one parameter: page: ft.Page

Example usage:

def config(page: ft.Page):
  page.on_resize = lambda e: print("Page resized!")

def main(page: ft.Page):
  page.add(ft.Text("Hello!"))

ft.run(main, before_main=config)

Summary by Sourcery

Implement Web Multi-View support for embedding Flet web apps into existing web pages

New Features:

• Add multi-view support for web applications
• Enable embedding Flet web apps into existing web pages
• Introduce initial data passing for multi-view scenarios

Enhancements:

• Refactor page and view control architecture
• Improve flexibility of web app rendering
• Add support for dynamic view management

Chores:

• Remove deprecated methods
• Clean up unused imports and code
• Simplify configuration handling

[Copilot]

Pull Request Overview

This PR adds multi-view support to allow embedding Flet web apps into existing web pages while improving the application's configuration and initialization flow.

• Introduces a new multi-view initialization mechanism with initial data passing and view constraints.
• Refactors configuration handling in both the worker setup and Flutter bootstrap process.
• Cleans up meta tags and inline configurations in the main HTML file.

Reviewed Changes

Copilot reviewed 28 out of 45 changed files in this pull request and generated 1 comment.

File	Description
client/web/python.js	Updated worker initialization to use flet configuration values.
client/web/index.html	Replaced meta tags with a flet config object and added multi-view initialization.
client/web/flutter_bootstrap.js	Refactored configuration merging and Flutter app bootstrap using a new config object.

Files not reviewed (17)

• client/lib/main.dart: Language not supported
• packages/flet/lib/flet.dart: Language not supported
• packages/flet/lib/src/controls/circle_avatar.dart: Language not supported
• packages/flet/lib/src/controls/markdown.dart: Language not supported
• packages/flet/lib/src/controls/page.dart: Language not supported
• packages/flet/lib/src/controls/view.dart: Language not supported
• packages/flet/lib/src/flet_app.dart: Language not supported
• packages/flet/lib/src/flet_backend.dart: Language not supported
• packages/flet/lib/src/models/multi_view.dart: Language not supported
• packages/flet/lib/src/models/page_args_model.dart: Language not supported
• packages/flet/lib/src/utils/locale.dart: Language not supported
• packages/flet/lib/src/utils/platform_utils_non_web.dart: Language not supported
• packages/flet/lib/src/utils/platform_utils_web.dart: Language not supported
• packages/flet/lib/src/utils/session_store_web.dart: Language not supported
• packages/flet/lib/src/widgets/flet_app_context.dart: Language not supported
• packages/flet/lib/src/widgets/flet_store_mixin.dart: Language not supported
• packages/flet/lib/src/widgets/page_context.dart: Language not supported

Comments suppressed due to low confidence (1)

client/web/python.js:33

• Ensure that the 'flet.noCdn' flag is set intentionally and that 'flet.pyodideUrl' is guaranteed to be defined when noCdn is true.

pyodideUrl: flet.noCdn ? flet.pyodideUrl : defaultPyodideUrl,

[Copilot]

[nitpick] If the commented-out view constraint is no longer required, consider removing it to improve code clarity; otherwise, add a clarifying comment explaining its purpose.

Suggested change

//maxWidth: 320,

[ndonkoHenri]

We should perhaps think of having just one src prop, and have intelligent ifs on dart end.