I built and modded Termux:X11 entirely on my phone using Termux… and somehow added a working FPS limiter lol
I still can’t believe I actually got this working.
I built and modded Termux:X11 entirely on my Android phone using Termux. No PC. Just Termux, Android build tools, a lot of trial and error, and help from ChatGPT when I got stuck.
The mod I added is a custom FPS limit option under the Output settings.
0 = auto / default refresh rate
1–600 = custom FPS value
The crazy part is that it actually works.
If I set it to something super low like 3 FPS, the whole X11 desktop becomes painfully choppy. If I set it to 30, it feels capped. If I set it to 60, it feels normal. If I set it to 90, XFCE/terminal reports 90Hz inside the session and it feels smoother, even though my phone display is still physically 60Hz.
Just to be clear: this is not overclocking the phone screen. My panel is still 60Hz. This is more like changing the internal framerate/pacing value that Termux:X11 reports and uses inside the X11 session.
The technical part:
Termux:X11 already had a Java path where it detects the Android display refresh rate and sends it to native code through:
sendWindowChange(width, height, framerate, name)
Originally, that framerate value came from Android’s detected display refresh rate.
I added an FPS limit preference in the Output settings, saved the value in SharedPreferences, parsed it safely, clamped it between 0 and 600, then used it to override the framerate before calling sendWindowChange.
So the logic is basically:
- 0 = use Android’s detected refresh rate
- 1–600 = force that value as the X11 framerate
- pass it into the existing native framerate path
The native side already uses that value for root_framerate / blank_interval, so it is not just a fake UI option. That’s why setting it to 3 FPS actually makes the desktop lag hard.
The build process was honestly painful. I had to deal with Java 17, Termux-native aapt2, AIDL problems, CMake/NDK issues on Android, APK signing, native lib mismatch, libXlorie.so replacement, and Android complaining about compressed native libraries.
Eventually I got it working by building the patched Java/resource side in Termux, making sure the correct official libXlorie.so was inside the APK as a stored native library, then signing the final APK.
This is definitely experimental and not upstream-ready, but I’m honestly proud of it. I don’t have a formal IT/programming background, so seeing this actually work inside XFCE on Termux:X11 feels insane.