Showing the name of certain visible layers in QGIS

Question

I'm working with QGIS 3.22.11-Białowieża. In my project, I have four layers and I need to show in the print composer the name of those that are visible, but only among the first three (I don't want to get the name of the fourth one that is always visible). The expression proposed in this post works well but it returns all visible layers (which is not what I want):

array_to_string(
  array_foreach ( 
   @map_layers,
   layer_property(@element,'name')
  )
)

To create the array of layers I'm interested in, I've tried the following

array_to_string(
  array_foreach ( 
   array (layer1, layer2, layer3),
   layer_property(@element,'name')
  )
)

But it returns the name of all layers in the new array, no matter if they're visible or not. I guess I need to use the is_layer_visible function, but all my attempts have failed. How should it be written?

Answer 1

You're almost there. Use is_layer_visible() with another array_foreach() function:

array_foreach (
    array_foreach (@map_layers,layer_property (@element,'name')),
    if (
        is_layer_visible(@element),
        @element,
        ''
    )
)

However, be aware of the fact that is_layer_visible() is only available in some contexts, see the comments to QGIS expression function is_layer_visible() missing in QGIS 3.28 and this GitHub issue.