jansule
commented
4 years ago When styling vector based layers, we stumble upon the problem that the applied OpenLayers Style often is a style function rather than a style object. This happens when styles are based on feature properties. In contrast to style objects, OpenLayers only accepts a single style function. A given style function cannot be extended directly, so I see two possible solutions to handle labeling in our case:
- Apply labeling on feature level (as the style function returns a style object for every feature)
- Apply additional SLDs that integrate labeling and can be parsed as a whole
The pro of point 2 is that the workflow would be quite similar to the one we use when styling WMS. But it would also mean that every style for vector based layers would have to be available in two versions (style without label, style with label).
The pro of point 1 is that we do not have to provide two versions of every style. But the handling for labeling VectorTiles would be more complex, as we can only access the features that are in the current extent.
Personally, I recommend following approach 2, as we leave the actual styling of the features to OpenLayers and can be sure that styling behaves similar to all other layers.
@geographika what approach would you rather have implemented?
@verendi @chrismayer
chrismayer
geographika
Currently CpsiMapview.view.menuitem.LayerLabels only supports WMS layers. The same class would ideally also work for vector based layers.
Note any updates would also need to be taken into account the following in CpsiMapview.view.layer.StyleSwitcherRadioGroup
if (layer.get('labelsActive') === true) { newStyle += ',' + labelClassName; }