How do I display message from from `adb shell` (or a shell script)?

Question

I expect it to be something like

adb shell am start SomethingArcane ... "Hello, world"

and the message box pops up on screen, saying "Hello, world".

Answer 1

Hacky workaround: DirectFB

With DirectFB and root access, you can display the text on screen directly, without Android at all.

I've implemented a program for this: directfbtext.

( echo "Hello, world"; echo "FLIP"; sleep 2; echo "QUIT" ) |  /h/bin/directfbtext --dfb:fbdev=/dev/graphics/fb0  --dfb:no-vt  /system/fonts/DroidSans-Bold.ttf 30 120 200 255

Note that it is probably not that easy to get DirectFB working on Android, but I happen to have it already configured.

---

Update Per user request, I've created and tested a "portable" pre-built version of directfbtext. Setting up and running:

1. Unpack directfbtext_deps.tar.gz into /data/local/tmp/;
2. Start adb shell, go root (su);
3. cd /data/local/tmp/directfbtext;

4. Create symlink from /usr/lib/arm-linux-gnueabi/ to /data/local/tmp/directfbtext:

   # mount -o remount,rw / /
   # mkdir /usr
   # mkdir /usr/lib
   # ln -s /data/local/tmp/directfbtext /usr/lib/arm-linux-gnueabi
   

5. Ensure display is on

6. LD_LIBRARY_PATH=. ./ld-linux.so.3 ./directfbtext --dfb:fbdev=/dev/graphics/fb0 --dfb:no-vt /system/fonts/DroidSans-Bold.ttf --dfb:system=fbdev 30 120 200 255
7. Type some text, followed by a line that reads "FLIP";
8. Observe the text visible on the display;
9. Type "QUIT" to exit directfbtext;
10. Interact with the device, so it updates display and clears remaining glitches caused by DirectFB.

Answer 2

FBTrueType-android

I have written a native android program FBTrueType-android to print TrueType font text directly to the display on the device using ADB.

It has many features including clearing the framebuffer (display) and changing the *.ttf font used, font color, font size, x and y positions.

It also can run with Zygote (android interface) running and it can capture the framebuffer from Zygote in fullscreen.

I setup a github repository for it which you can access here, alternatively you can clone the repository like this:

$ git clone https://github.com/mikelinux/fbtruetype-android.git

You will need to be setup to cross compile for ARM, the README file has full instructions on doing this.

Enjoy, and please post your feedback.

Mike