Dont cache BaseOnSourceLayers which use WritableLayers as their SourceLayer about mapsui

[pauldendulk]

What are you referring too exactly. There is no 'BaseOnSourceLayers' in the Mapsui code. Are you using the WriteableLayer within a RasterizingLayer?

[EmaDozer]

I recognized that the IBaseOnSourceLayer interface is not part of Mapsui. But the issue stays the same. Which layers are cached? I saw a commit which prevent to cache WritableLayers but all other layers will be chached?

I think the question is this:
What happens if I change the coordinations of features of a cached layer?

The issue which i encountered is, that the cache is returning different SkiaPaths for "nearly" the same ViewPort and the exact same LineString, which appears for the user as "jumping" lines. The user can drag lines while the ViewPort stays the same. But somehow different SkiaPaths are cached. Here are the key (Viewport, float, TPath) and value of the VectorCache.GetOrCreatePath() method:

key: (BL: (X=9447737,444718989,Y=6016036,122831078) TR: (X=9515876,695165673,Y=6121144,541073304), 0, LINESTRING (9525303.71018535 6081266.624317251, 9496860.208610183 6067012.749910232), 2)
value: {Left=449,3636,Top=422,3461,Width=208,63641,Height=85,38812}

key: (BL: (X=9447737,444718987,Y=6016036,122831079) TR: (X=9515876,695165671,Y=6121144,541073305), 0, LINESTRING (9525303.71018535 6081266.624317251, 9496860.208610183 6067012.749910232), 2)
value: {Left=467,3636,Top=425,69656,Width=190,63641,Height=85,03766}

The differences of the ViewPort are in bold (the very last number of the X and Y coordination).

[charlenni]

I would say, you have to provide some more information. What provider do you use, what layer do you use? Best would be to provide a small sample, with which it is possible to reproduce the problem.

[EmaDozer]

I have a custom layer which uses WritableLayer as its source. So its basically a wrapper layer which referencing the features returned by the WritableLayer. I dont use any provider.

For the WritableLayer the IModifyFeatureLayer interface is used, to indicate that this layer should not be cached. For now, I also use this interface for my custom layer, which solves the issue.

Is that the considered solution for custom, modifiable layers? Took me a while to figure it out.

[pauldendulk]

In v5 there is no distinction between layers in how they cache. If a feature is modified in user code you need to call IFeature.Modified() to indicate the cache should be updated.