Hello, I am an amateur photographer and I recently moved from an old iPad to a Galaxy Tab S 10.5 with custom rom, Android 6.
On the iPad the thumbnails were created while importing photos from iTunes, and even at the first time I opened the gallery everything was there.
Now I just copy a Photo folder into the root of my microSD card and I use QuickPic Gallery (but any other gallery is the same) to view the photos. I have 2-3k pictures and every time I open a gallery for the first time i see only black squares and they slowly appear, same story when I open a photo full-screen.
Pictures that I copy into the microSD card have no thumbnails.
I don't want to wait for the creation on-the-fly when I open a folder or manually open everything after copying so the next time will be cached!
How can I trigger the creation of all necessary thumbnails just after I copied my photos?