App: Resources Resizer
Developer: Adrian Zagozdzon
Genres: Entwickler-Tools, Grafik und Design

Drop your resources files in the biggest resolution that you need in your app.
App can resize graphic files :png, jpg, jpeg, gif, webp, heic, heif, bmp, tiff. You can drop whole drawable directory all .xml files will be saved in the drawable directory.
 
If you drop files:  image.png in 640x640 resolution & gradient.xml you will get:

  drawable-xxxhdpi/
    image.png 160x160
  drawable-xxhdpi/
    image.png 240x240
  drawable-xhdpi/
    image.png 320x320
  drawable-hdpi/
    image.png 480x480
  drawable-mdpi/
    image.png 640x640
  drawable/
    image.png 640x640

Release notes:
Added full support for the webp format.
Added feature that allow user to skip images below chosen resolution and save them in the drawable-anydpi or drawable-nodpi directory