3

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".

2

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.
  • Maybe you can tell what need to be configured? – not2qubit Jan 8 '15 at 0:16
  • The main thing is probably a Debian in chroot. – Vi0 Jan 8 '15 at 1:20
  • Could you provide a binary? (Or instructions how to compile with NDK?) – not2qubit Jan 14 '15 at 23:08
  • Unfortunately static binaries are tricky to get with DirectDB. The program was build not using Android NDK and depends on Debian libraries. I'll try to hack up "semi-portable" version of it now. – Vi0 Jan 14 '15 at 23:34
  • 1
    @user1147688, Done. You can try testing it. – Vi0 Jan 15 '15 at 0:28
1

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

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