Optimize markers calculations

[TheLastGimbus]

This PR is attempting to optimize and shrink all calculations that are done when user drags map with a lot of markers

Hopefully, I will get it to state where we have full 60 fps with 5k markers, but we will se how it goes

Fixes #824 I would really want to Yeah, pretty much - I don't see we how could do much better than this

[TheLastGimbus]

This CI is broken...

[TheLastGimbus]

You literally commented that when I was about to push it 😄

[TheLastGimbus]

This may look kinda hack-ish, but this actually brough whole loop's time (on my tablet) from ~20 to ~10ms! On 5k markers!

(As always: When zoomed to no markers and not zooming in/out)

[TheLastGimbus]

@ibrierley You proposed to cache them per-zoom-level. Out of curiosity, I printed when zoom changes and:

I/flutter (16890): 6.249008887924742
I/flutter (16890): 6.254358513273377
I/flutter (16890): 6.255482934237276
I/flutter (16890): 6.261930705947585
I/flutter (16890): 6.266114410749081
I/flutter (16890): 6.2766681718506305
I/flutter (16890): 6.283982456742614
I/flutter (16890): 6.2892041742113065
I/flutter (16890): 6.296456503011495
I/flutter (16890): 6.301633471546501
I/flutter (16890): 6.303673583816311
I/flutter (16890): 6.30882487202124
I/flutter (16890): 6.311932043194194
I/flutter (16890): 6.317053908214326
I/flutter (16890): 6.3190726270623445

We probably couldn't phisically fit so many ints into whole device ram 😆 So I guess that's the best we can settle on

[TheLastGimbus]

Okay, this is ready for review and merge

Hopefully, I will get it to state where we have full 60 fps with 5k

I have 30 fps at 5k markers and 60 at 2.5k - not bad 👍

[TheLastGimbus]

One important thing I noticed:

When you have a simple widget as markers, and make it a const, fpses can sometimes double when you have all of them on the screen

We could add this hint somewhere in the documentation

(but, of course, behavior between devices/widget cases can vary)

[KlausJokisuo]

Any news on this?

[TheLastGimbus]

I was just about to apologize that I'm running late with pushing commits as always, but, oh, it's not me 😄

We are just waiting for @johnpryan review 👍

[KlausJokisuo]

I was just about to apologize that I'm running late with pushing commits as always, but, oh, it's not me 😄

We are just waiting for @johnpryan review 👍

No worries mate, what kind of performance improvements can except for example with 2000 markers and 200 visible.

[TheLastGimbus]

Yeah, not that much, but it's always something

I think we need to make some new plugin for markers that will base on Canvas or something for that many markers

Edit: Oh, if that was a question - on my tablet, 3,5k markers where ~20fps when zoomed to 30 visible, and like 15fps when 200 visible. After optimization, 3.5k 60fps when <100 visible, then maybe 45fps when 200 visible 👍

[KlausJokisuo]

Yeah, not that much, but it's always something

I think we need to make some new plugin for markers that will base on Canvas or something for that many markers

Edit: Oh, if that was a question - on my tablet, 3,5k markers where ~20fps when zoomed to 30 visible, and like 15fps when 200 visible. After optimization, 3.5k 60fps when <100 visible, then maybe 45fps when 200 visible 👍

Thanks! Keep up the good work and sorry I phrased my question oddly. 😅

[kengu]

All RFCs from @johnpryan are resolved in code. LGTM.

[kengu]

@TheLastGimbus The only remaining thing to do is to resolve the conflicts with master in lib/src/layer/marker_layer.dart

[TheLastGimbus]

Done! All working, markers rotating correctly 👌 @kengu ready to merge 👍

[kengu]

@TheLastGimbus I got this error in the log when opening the "A lot of markers" page in the example-app.

======== Exception caught by widgets library =======================================================
The following RangeError was thrown building ManyMarkersPage(dirty, state: _ManyMarkersPageState#bb88c):
RangeError (end): Invalid value: Only valid value is 0: 500

The relevant error-causing widget was: 
  ManyMarkersPage file:///Users/kengu/src/git/flutter_map/example/lib/main.dart:66:45
When the exception was thrown, this was the stack: 
#0      RangeError.checkValidRange (dart:core/errors.dart:333:9)
#1      List.sublist (dart:core-patch/growable_array.dart:84:38)
#2      _ManyMarkersPageState.build (package:flutter_map_example/pages/many_markers.dart:85:56)
#3      StatefulElement.build (package:flutter/src/widgets/framework.dart:4612:27)
#4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4495:15)

This fixes it

allMarkers.sublist(0, min(allMarkers.length, _sliderVal))

@johnpryan I've testet this on my phone and it looks good. The merge is blocked by your request for change, which I think is mostly resolved.

[TheLastGimbus]

Done 💯

[TheLastGimbus]

@kengu you can pretty much press merge 👌
_{I think}

[kengu]

@kengu you can pretty much press merge 👌
I think

Waiting on @johnpryan - unable to merge until changes are ack-ed by him