Question

I just want to clarify, with the res folders in android, with lower resolution devices, they automatically get the same named asset from the ldpi folder? This is so I can make different assets for smaller screens?

Do I need to have assets in all 4 folders (ldpi – xhdpi) for it to work on all sized devices? Or can I just have assets in one folder if the assets are all the same for all devices?

And what if my assets are only different for low res devices, do I need to mirror the contents of each of the other folders so they all have the same assets in?

Answer 1

I would suggest reading this article thoroughly to get an understanding of exactly how it works, but basically, it will find the closest matching size resource that is available, so no, you don’t need to mirror across all folders necessarily.

From the qualifiers section particularly, this quote explains it well.

Be aware that, when the Android system picks which resources to use at
runtime, it uses certain logic to determing the “best matching”
resources. That is, the qualifiers you use don’t have to exactly match
the current screen configuration in all cases in order for the system
to use them. Specifically, when selecting resources based on the size
qualifiers, the system will use resources designed for a screen
smaller than the current screen if there are no resources that better
match (for example, a large-size screen will use normal-size screen
resources if necessary). However, if the only available resources are
larger than the current screen, the system will not use them and your
application will crash if no other resources match the device
configuration (for example, if all layout resources are tagged with
the xlarge qualifier, but the device is a normal-size screen). For
more information about how the system selects resources, read How
Android Finds the Best-matching Resource.