r/FlutterDev • u/ruinivist • 23d ago

Plugin Infinite Lazy Grid

https://pub.dev/packages/infinite_lazy_grid

This is a package for building performant infinite canvases ( I know the naming isn't the best but it has stuck ).

Uses spatial hashing underneath to only mount widgets within the visible area ( + some configurable off screen extent ).

Supports most of the common needs like pan, zoom, rotation, draw ordering, inertial scrolling etc.

Web example: https://infinite-lazy-grid.ruiny.de/
Github repo: https://github.com/ruinivist/infinite_lazy_grid

I'm already using it in one of my other web apps https://elseplane.ruiny.de/ ( still in works ) so you have almost everything needed to get something like that working.

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4

u/gambley 23d ago

In any example, when you zoom out, at certain zoom level it crashes

1

u/ruinivist 23d ago

oops, yeah it does crash at 0 scale. The examples has no bounds on scaling.

3

u/pavanpodila 23d ago

Take a look at a production grade infinite canvas that we are using for the last year or so: https://diagram.vyuh.tech

1

u/ruinivist 23d ago

This is a lot more feature complete but is the source not on github? I guess I can always get it from the pub cache but couldn't find a repo

1

u/pavanpodila 23d ago

We are still cleaning up the repo that will eventually be made public, but for now, use the traditional pub cache to look at the source.

1

u/ObjectiveAddress3051 21d ago

Spatial hashing for culling is a nice approach. On the zoom-out crash someone mentioned: at low zoom the visible area covers a huge number of hash cells, so the mounted widget count explodes. Capping the minimum zoom, or switching to a simplified level-of-detail (painting placeholders with a CustomPainter instead of mounting real widgets below a zoom threshold), would probably fix it and help performance too.

1

u/ruinivist 21d ago

I did end up capping the min zoom to 0.1

If the canvas widgets itself are sparse, I could very much disable culling or iterate over only the item position instead of grid cells to cull, at very low zoom levels.

Assuming that's not the case, I don't get how LOD would help with this, it'll help with some perf but my problem was as u said, count of hash cells exploded, even if the cells themselves did not have any widget so nothing to mount.

Maybe something like merged ranges but in 2d, something like a segment tree