Drawing of paths with separate segments in a single layer?

[moving-bits]

(Continuing discussion from #969 (reply in thread) in a separate thread for this topic)

Original question:

I have a couple of paths to draw (eg.: each path represents an accumulated track history for a specific month).

• Each path can consist of several unrelated segments (eg.: track history for a single day),
• each segment consisting of several points (eg.: the places you have visited on that specific day) - this should be an actual path with connected elements.

I'm using a PathLayer to display this, but I have not been able to show the segments unconnected, so I'm currently putting each segment into its own layer. Surely there must be a better way to do this.

Reply given in #969 (comment):

GPX tracks with multiple track segments: need a path layer per track segment (Mapsforge + VTM).
Map libraries do not care if 2 lines are "related", if not connected then they are separate line layers.

For Mapsforge we currently use something like this:

c.path = AndroidGraphicFactory.INSTANCE.createPath();
ArrayList<Geopoint> segment = segmentIterator.next();
while (segment != null) {
    final Iterator<Geopoint> geopointIterator = segment.iterator();
    Geopoint geopoint = geopointIterator.next();
    c.path.moveTo((float) (MercatorProjection.longitudeToPixelX(geopoint.getLongitude(), mapSize) - topLeftPoint.x), (float) (MercatorProjection.latitudeToPixelY(geopoint.getLatitude(), mapSize) - topLeftPoint.y));

    while (geopointIterator.hasNext()) {
        geopoint = geopointIterator.next();
        c.path.lineTo((float) (MercatorProjection.longitudeToPixelX(geopoint.getLongitude(), mapSize) - topLeftPoint.x), (float) (MercatorProjection.latitudeToPixelY(geopoint.getLatitude(), mapSize) - topLeftPoint.y));
    }
    segment = segmentIterator.hasNext() ? segmentIterator.next() : null;
}

which separates segments nicely, thus having to use only a single layer for the whole track (or even multiple tracks).

I'm looking for something similar for VTM to be able to stick with a fixed number of layers, as

• layer index defines visibility and track layer is not top-most for me
• number of segments is unknown to me upfront, and can vary during lifespan
• layer index values can have no gaps.

Any other type of layer I can choose by which I can achieve something similar like in our Mapsforge code?

[devemux86]

Can study the vtm-jts module and create any extra custom layers.

In any case map engines are different, so must not expect same API.
Currently the general rule is that separate lines use separate layers.

[moving-bits]

Found a simple solution meanwhile:

Instead of

final PathLayer trackLayer = new PathLayer(map, color, width);
map.layers().add(trackLayer);
trackLayer.setPoints(segment);

I'm using this now:

final Style pathStyle = Style.builder().strokeWidth(width).strokeColor(color).build();
final LineDrawable path = new LineDrawable(segment, pathStyle);
trackLayer.add(path);

(with trackLayer being the VectorLayer holding all my tracks now).

Thanks for your help pointing me into the right direction!

[devemux86]

Thanks for writing the solution!
It's nice that there is already an alternative.