Patch webOS Random Wallpaper Switching - Revision history

Odontastic: /* The Wallpaper Switcher Script */

2009-10-18T02:04:03Z

The Wallpaper Switcher Script

Hparsons at 19:19, 4 August 2009

2009-08-04T19:19:31Z

Hparsons: Added alternative uses section, and "missingpre" script

2009-08-04T19:06:37Z

Added alternative uses section, and "missingpre" script

Hopspitfire at 08:54, 3 August 2009

2009-08-03T08:54:24Z

Hopspitfire: Random Wallpaper Switching moved to Patch webOS Random Wallpaper Switching: webOS patch

2009-08-03T08:47:32Z

Random Wallpaper Switching moved to Patch webOS Random Wallpaper Switching: webOS patch

Phwelo at 15:34, 31 July 2009

2009-07-31T15:34:23Z

Hopspitfire: root -> accessing linux

2009-07-28T23:12:03Z

root -> accessing linux

Hopspitfire: /* Enabling Cron */

2009-07-26T00:26:47Z

Enabling Cron

Hopspitfire: New page: === Goal=== On my desktop I have installed desktop drapes and my wallpaper switches every few hours to a random image in a wallpapers folder. I wanted to have the same functionality on m...

2009-07-22T16:41:42Z

New page: === Goal=== On my desktop I have installed desktop drapes and my wallpaper switches every few hours to a random image in a wallpapers folder. I wanted to have the same functionality on m...

New page

=== Goal===

On my desktop I have installed desktop drapes and my wallpaper switches every few hours to a random image in a wallpapers folder. I wanted to have the same functionality on my pre.

=== Requirements===

* [[Portal:Accessing_Linux | A rooted Pre]]
* [[Next_steps | Installed backdoor with sudo]]
* The PATH variable should be set up in your .profile in your backdoor account, for example mine is set as follows:
<pre><nowiki>export PATH=$PATH:/bin:/sbin:/usr/bin:/usr/sbin/:/usr/local/bin:/opt/bin:/opt/sbin</nowiki></pre>

=== Procedure===

Note: I prefer doing everything with sudo and not logging in as root via the backdoor. I would recommend getting into the same habit.

==== Transfering Wallpapers====

* Connect your Pre to your computer as a USB drive.
* Create a folder named 'wallpapers' on the Pre (if its not already there).
* Put all your wallpapers there.
* Disconnect the Pre from your PC. You might want to make sure to disconnect it safely so everything writes to storage okay.

Make sure to remove any wallpapers which you don't want to show up, though, since the switcher will pick a random one.

==== Enable Write Access====

<pre><nowiki>sudo mount -o remount,rw /</nowiki></pre>

==== Enabling Cron====

The [[tracking]] guide has a nice bit about enabling crond on the Pre. It looks like its already pre-installed, just not set up to start. You will need to edit /etc/event.d/crond to enable cron to start. The settings should look like this:

<pre><nowiki>
# -*- mode: conf; -*-

# jobfile for busybox crond, with pre-start commands to create the
# directory and files it wants by default. That there's not 'start
# on' stanza is intentional: it's for development use only. We can
# turn it on later if we need it, e.g. to keep the clock synced. It
# does work.

start on stopped configure
stop on started start_update

respawn

exec /usr/sbin/crond -f -L /var/log/crond

pre-start script
mkdir -p /var/spool/cron/crontabs
ln -sf /etc/cron/crontabs/root /var/spool/cron/crontabs/root
end script
</nowiki></pre>

A few notes here. Unlike the Dropbear and other scripts I make my upstart scripts so that essential services don't stop when the device exists runlevel 2. This seems to shutdown these services whenever the device locks. I prefer that my upstart services stop only when the updater runs. Also I have made cron log to a separate file under /var/log so that it can be monitored better.

One thing to note about the standard script for cron on the Pre is that the /var/spool/cron/crontabs directory is created every time the process runs and a symlink to /etc/cron/crontabs/root is created. To my surprise this file does not exist. So we need to create it:

<pre><nowiki>
sudo mkdir /etc/cron/crontabs
sudo sh -c 'echo > /etc/cron/crontabs/root'
</nowiki></pre>

Now to start up crond:

<pre><nowiki>sudo -i initctl start crond</nowiki></pre>

==== The Wallpaper Switcher Script====

First lets make a place for the script:

<pre><nowiki>sudo mkdir /opt/share/wallswitcher</nowiki></pre>

Edit wallswitcher.sh inside /opt/share/wallswitcher directory and place the following code there:

<pre><nowiki>
#!/bin/sh

main()
{
DIR='/media/internal/wallpapers/'
IFS="
"
NUM_FILES=0
for cur in `ls -1 $DIR`; do
if [ -f "$DIR$cur" ]
then
NUM_FILES=$((NUM_FILES+1))
eval "FILE_$NUM_FILES=$cur"
fi
done

RANDOM_NUMBER=`awk "BEGIN{srand();print int($NUM_FILES * rand()) + 1;}"`
eval "RANDOM_FILE=\$FILE_$((RANDOM_NUMBER))"
IMPORT_STRING="{ \"target\": \"$DIR$RANDOM_FILE\" }"
SET_STRING="{ \"wallpaper\": { \"wallpaperName\": \"$RANDOM_FILE\", \"wallpaperFile\": \"$DIR$RANDOM_FILE\" } }"

echo "Found $NUM_FILES in $DIR"
echo "Using random file: $RANDOM_FILE"
echo "JSON Import String: $IMPORT_STRING"
echo "JSON Set String: $SET_STRING"

eval "luna-send -n 1 palm://com.palm.systemservice/wallpaper/importWallpaper '$IMPORT_STRING'"

eval "luna-send -n 1 palm://com.palm.systemservice/setPreferences '$SET_STRING'"
}

main
</nowiki></pre>

Save the file and make sure it has execute permissions. The following command will insure that:

<pre><nowiki>sudo chmod 755 /opt/share/wallswitcher/wallswitcher.sh</nowiki></pre>

Some notes on the script:
* I am a Java/Groovy developer mostly and am not as good at shell scripting as I would like. Any improvements on the script itself are welcome
* The main piece of code that performs the switch are the two luna-send commands. T he first command is required if a wallpaper has never been used before and will generate some thumbnails and copy the main image into /media/internal/.wallpapers. The second luna-send command actually performs the switch.
* This method currently only supports wallpapers sized to exactly 320 x 480 px. The import luna-send call can take more parameters in its JSON string, such as scaling and x/y offsets from center. I have not used these yet since all my wallpapers are correctly sized.
* Again, being a not-so-good shell developer, the way I obtain random numbers and use them is a bit wrong. Awk is used to get a random number. Instead of arrays (as in bash), dynamic variable naming is used.
* The DIR variable controls where the script looks for wallpapers—you can change it to where your pictures are instead. Currently the scan is not recursive.

==== Testing the Script====

If you have more then one wallpaper in /media/internal/wallpapers, you can test the switcher with the following command:

<pre><nowiki>sudo /opt/share/wallswitcher/wallswitcher.sh</nowiki></pre>

The response should look something like this:

<pre><nowiki>
Found 24 in /media/internal/wallpapers/
Using random file: wall_409.jpg
JSON Import String: { "target": "/media/internal/wallpapers/wall_409.jpg" }
JSON Set String: { "wallpaper": { "wallpaperName": "wall_409.jpg", "wallpaperFile": "/media/internal/wallpapers/wall_409.jpg" } }
** Message: serviceResponse Handling: 2, { "returnValue": true, "wallpaper": { "wallpaperName": "wall_409.jpg", "wallpaperFile": "\/media\/internal\/.wallpapers\/wall_409.jpg", "wallpaperThumbFile": "\/media\/internal\/.wallpapers\/thumbs\/wall_409.jpg" } }
** Message: serviceResponse Handling: 2, { "returnValue": true }
</nowiki></pre>

If the two service calls are not returning correctly, something is wrong. Contact me (fxdemolisher[at]gmail[dawt]com) if you are stuck debugging it.

==== Schedule the Script====

This step is pretty easy. Since you have an empty root crontab set up all that needs to be done is a scheduling command. Edit /etc/cron/crontabs/root and place the following scheduling test line:
<pre><nowiki>*/1 * * * * /opt/share/wallswitcher/wallswitcher.sh > /opt/share/wallswitcher/wallswitcher.log 2>&1</nowiki></pre>

This will execute the switcher every minute and log to the /opt/share/wallswitcher/wallswitcher.log log. After you have it switching correctly every minute you can edit the cron definition to run as often as you like. Mine is set to run at the top of the hour using this line:

<pre><nowiki>0 * * * * /opt/share/wallswitcher/wallswitcher.sh > /opt/share/wallswitcher/wallswitcher.log 2>&1</nowiki></pre>

NOTE: Do not use crontab -e as this does not really write to /etc/cron/crontabs/root and will be overriden when the device restarts.

==== Restore Read-Only Filesystem====

<pre><nowiki>sudo mount -o remount,ro /</nowiki></pre>

Tested and verified as written by optik678.

=== Acknowledgements===

I would like to thank this site and the wonderful hackers on it. I would not be able to do this without various examples from other pages.

@@ Line 161: / Line 161: @@
 <pre><nowiki>/sbin/stop crond && /sbin/start crond</nowiki></pre>
-'''Result.''' Every minute this will over-ride whatever wallpaper was set. Obviously, this won't force anyone to return your device, nor will it work if someone knows what they're doing with the Pre, but if your wallpaper is obnoxious enough, you might get lucky and have them call you back.
+'''Result.''' Every minute this will over-ride whatever wallpaper was set.
 === Acknowledgements===
 I would like to thank this site and the wonderful hackers on it. I would not be able to do this without various examples from other pages.

← Older revision		Revision as of 08:54, 3 August 2009
Line 1:		Line 1:
		+	{{template:patch}}
	===Homebrew App for Random Wallpaper Switching===		===Homebrew App for Random Wallpaper Switching===

← Older revision		Revision as of 15:34, 31 July 2009
Line 1:		Line 1:
		+	===Homebrew App for Random Wallpaper Switching===
		+
		+	There is now a homebrew application (no rooting required) that allows this same function without performing the patch below. It can be found at http://forums.precentral.net/homebrew-apps/195990-switcharoo-random-wallpaper-switching-v0-9-0-7-30-a.html
		+
	=== Goal===		=== Goal===

@@ Line 50: / Line 50: @@
+{
    DIR='/media/internal/wallpapers/'
    IFS="
+"
    NUM_FILES=0

← Older revision	Revision as of 08:47, 3 August 2009
(No difference)

@@ Line 5: / Line 5: @@
 === Requirements===
-* [[Portal:Accessing_Linux | A rooted Pre]]
+* [[Portal:Accessing_Linux | Access to Linux]] on your Pre.
 * [[Next_steps | Installed backdoor with sudo]]
 * The PATH variable should be set up in your .profile in your backdoor account, for example mine is set as follows:

@@ Line 29: / Line 29: @@
 ==== Enabling Cron====
-The [[tracking]] guide has a nice bit about enabling crond on the Pre. It looks like its already pre-installed, just not set up to start. You will need to edit /etc/event.d/crond to enable cron to start. The settings should look like this:
+Go [[Crond | here ]] to enable crond.
 ==== The Wallpaper Switcher Script====