What's the meaning of v19 behind drawables?

Question

What's the meaning of v19 behind drawable? for example: drawable-hdpi-v19?

Thanks!

Answer 1

Table 2 in doc describes all possible options for res folders.

v19 means at least API19 (4.4)

Answer 2

It describes the API Level. In this case API 19+ (Android 4.4)

That is probably because of the updated Design guidelines. For example touch:

Touch feedback

Before Android KitKat, Android's default touch feedback color was a vibrant blue. Every touch resulted in a jolt of high-contrast color, in a shade that might not have mixed well with your brand's color(s).

In Android KitKat and beyond, touch feedback is subtle: when something is touched, by default its background color slightly darkens or lightens. This provides two benefits: (1) sprinkles of encouragement are more pleasant than jolts, and (2) incorporating your branding is much easier because the default touch feedback works with whatever hue you choose. Check the updated Touch Feedback page for more details.

Answer 3

The API level of the resource (v19 -> 19+ kitkat 4.4).

You could use it for drawable, values, xml etc. for every resource.

The API level supported by the device. For example, v1 for API level 1 (devices with Android 1.0 or higher) and v4 for API level 4 (devices with Android 1.6 or higher). See the Android API levels document for more information about these values.