Rename "background" to "cover" or "fill"

[edenh]

Background is misleading because you can have many of them and they don't have to be "in the back". Let's rename to "cover".

[yhahn]

Note: similar concept in Photoshop is called a Fill layer (http://www.dummies.com/how-to/content/how-to-use-fill-layers-in-photoshop-cs6.html)

[mourner]

Is there an actual use case for many backgrounds or putting background in a different place? Cover doesn't sounds very intuitive to me... I'd rather throw an error if there are several backgrounds or if it's not in the back, and keep "background" name.

[edenh]

Multiple background layers is useful. For example, a background layer with a transparent background-image with another solid color background layer underneath. Also, it is useful whenever you want to "tint" the entire map or a portion by applying a semi-transparent background layer higher up in the stack.

[nickidlugash]

I would be amenable to "Fill" layer if we weren't already using this layer name for something else...perhaps regardless of whether we implement polygon fills and lines in one layer (#223), we can still rename the current "fill" layer to "polygon" layer and rename "background" to "fill"? Too confusing?

[edenh]

I tend to think of background layers in terms of the css property: background-size: "cover".

[ljbade]

What happens in the last background layer is transparent? I guess the glClearColor comes through?

[jfirebaugh]

I was thinking along the same lines as @nickidlugash. This doesn't unlock any new capabilities, so let's pause on it until we see where #223 ends up.

[jfirebaugh]

We should do this for v9, and then reintroduce background as a style-wide global property. Meanwhile cover layers should require a source, and only render on loaded tiles.

That enables mapbox/mapbox-gl-js#3280 / mapbox/mapbox-gl-native#119.

[kkaefer]

Why should they require a source?

[jfirebaugh]

So that you can have two different "backgrounds":

• A base color or grid that shows up behind unloaded tiles
• A "land" background that shows up on loaded tiles where there are no other features

[lucaswoj]

This issue was moved to mapbox/mapbox-gl-js#4084