[Spec] Improve the performance of this Framework

[huangjinshe]

[The feature]

In the Xamarin.Forms there is a really big design problem.
Everytime navigate to a page, it will start to initial() the content page (No matter it's a navigation page, tabbed page, Master detail page, even maybe there is a navigation page in a Master detail page as a content page),
and after pop() the content page from the navigation page , the execute dispose() to destroy the content page.

This kind of design give us so much bugs, especially when we are trying to reuse the exists page, just because last time it already disposed, then it initialize again, the result is : It still slow..... The things that really let people mad is: when we reuse a exists page, just because it initial again and reset again, the ListView in the page still need to reload again(that will let us wait more time), selected item gone, the page scroll reset to 0....etc.... eventually give us much more problems and bugs.

You may ask why we just can't create a new content page every time, but it will cost big running time for low performance device, that's why we want to reuse a existsting page, but that design problem never fixed in Xamarin.Forms

More details: [Enhancement] Need team finish the fix performance issue pull request!

I really hope in the new framework we can avoid this kind of design. let the low performance device running for faster(at least more faster running when open a page second times).

[huangjinshe]

Those people who downvote this, can at least give you reason for discussion? Thanks.

I really hope to know these people did used Xamarin before? Did they know this Bug and reported to Bugzilla or Github of Xamarin ? did they used Xamarin on low performance devices before?
If they did not. I hope they would understand:

.NET MAUI is the next generation of Xamarin Forms

And:

.NET MAUI is essentially the next evolution of Xamarin.Forms

In that case, I hope we really need to carefully handle this kind of design problem in the beginning.

[charlesroddie]

This is your issue:

Title: preserve inactive navigation pages when pushing and popping.
Pros: avoid reinitializing pages which can saves time and preserves state
Cons: increases memory usage

Please note small number of words needed to explain it, the close correspondence between the title and the description, and the omission of the inapplicable word "bug".

As given, this still woudln't be accepted because of the con, which will adversely and unexpectedly affect many users. So I would adjust this to "give an option to preserve inactive navigation pages when pushing and popping".

I don't understand why you have let this bother you and not just worked around this. Writing a navigation system is very easy, so much so that I find it very strange that Xamarin.Forms comes with one built in. So you can just write your own and ignore the Xamarin.Forms NavigationPage.

[huangjinshe]

@charlesroddie , Thanks for make this issue more clear. I'm really sorry for my bad English.

I don't know did you used UPW version of Xamarin.Forms or not . On the contrary, frequent creation and release of controls will further increase the memory footprint. So actually I did not even worry about increased memory usage, Actually I even think this is the better way to fix that (Of course we can't use this solution fix memory usage problem with other things caused.)

"give an option" solution is acceptable, I don't have any problem with that. Actually maybe you can see I actually add some variable to fix it of UWP in that PR.

The problem not only happen in NavigationPage, Also MasterDetailPage, change the root MainPage, or any other Navigational thing all had it, I don't think it's very easy to writing it, otherwise Xamarin.Forms team already did it by themselves.

Some feature like this need to consider at the beginning, If too late, it will cause too much Bug for us. That's why I add this issue right now.