In order to define different dimension values for 1080p and 720p android TV, I need to decide which qualifier I should use. When I'm trying to use something like values-sw1080p,values-sw720p, it doesn't work. The values in dimes.xml doesn't affect anything. But it works if I'm using qualifier like -sw540dp,-sw360dp. I don't really understand why like that. Any idea? Thanks.
First of all, you are substantially correct. You can use
sw360dp/ : 720p screens sw540dp/ : 1080p screens
The reason why
sw720p/sw1080p don't work is because they don't exist as qualifiers.
This is the official documentation about working with different screen sizes. As you can read, there are two different units to take into account if you want to calculate your
dp folder: the pixel count (e.g., 720) and the pixel density (that is, the dot-per-inch unit, or how many pixels fit into a single inch).
The formula is pretty simple:
px = dp * (dpi / 160)
while in this case we have:
dp = px * 160 / dpi
Of course, a TV can have different densities: this table tells you more about it (source: official documentation).
Let's assume we have a 1080p display with an extra high density (@320 dpi). We do the math
dp = 1080 * 160 / 320 = 540
So we get the appropriate folder to put your resources in.
EDIT: on that same page, it is stated that there is a specific
tvdpi qualifier that you can use for your TV-related resources (around