Make EditText.highlightText faster by adding spans directly

[tom93]

This makes searching in medium/large texts (e.g. files opened in the File Editor) faster by orders of magnitude, especially when there are many matches. Tested on Android 9 and 14 with a 100KB text file (but the speed difference should also be noticeable on smaller files).

From the commit message:

The previous code called setText() after adding each span, which is very slow when there is a lot of text. It is enough to call setText() once at the end if any matches were found.

But we can do even better: we can add the highlighting spans directly to the existing Editable of the EditText, and skip setText() entirely, thus avoiding any copying of the text.

The documentation of EditText.getText() says "The content of the return value should not be modified. If you want a modifiable one, you should make your own copy first." (inherited from TextView), but adding spans to the return value appears to work fine.

[naveensingh]

I tried using a 200KB text file and got a crash, I guess the File editor could use some work.

[tom93]

Ha ha, I can open a 1MB text file on an Android-x86 9 VM with 2GB RAM, but it does increase resident RAM usage by a whopping 200MB (217MB when idle, 418MB with file open).

Thanks for merging! (Edit: I misread the "Merge" commit above -- the PR wasn't merged yet at the time.)

[naveensingh]

Seems to work fine, thanks!

[tom93]

Thanks! (I misread the earlier merge commit and said my first thanks too soon. I swear I wasn't trying to be passive-aggressive!)

[naveensingh]

@tom93 I figured, don't worry about it :)

[naveensingh]

I can open a 1MB text file on an Android-x86 9 VM with 2GB RAM

By the way, when fixing bugs or implementing features, please try to test things on real devices with average specs or emulators (if possible).