Skinpeel

Change vita's lockscreen foreground and background randomly. Based on reverse engineering the fruitpeel plugin.

Changes from the original plugin:

• Only supports firmware 3.60 for now.
• Uses BC1/DXT1 images instead of 8bpp png files. Generally it should have better quality images with reduced memory usage.
• Random mode: select random bg/fg on every lock.
• Can also change the foreground image.

Usage

Use the convert tool to convert your images to .spraw files.

Add skinpeel.suprx under *main in your taihen config. Copy the background image to ur0:data/skinpeel/foo/bg.spraw and the foreground to ur0:data/skinpeel/foo/fg.spraw.

If you want to randomly use multiple images, create extra directories in ur0:data/skinpeel. For example, if you have ur0:data/skinpeel/a and ur0:data/skinpeel/b, on each lock the plugin will randomly choose a or b and load the images inside. You can also have multiple image files as long as they start with fg or bg and end with .spraw. The plugin will choose a directory first, then an fg/bg image later. So, for example with a directory structure like this:

ur0:data/skinpeel
 + foo
   + bg0.spraw
   + bg1.spraw
   + fg0.spraw
   + fg1.spraw
 + bar
   + bg.spraw
   + fg.spraw

On each lock the plugin will choose randomly between foo and bar. If it chooses bar, it will use the bar/bg.spraw and bar/fg.spraw. However, if it chooses foo, it will randomly select between foo/bg0.spraw and foo/bg1.spraw for background (and the same for fg).

You can override only the foreground or only the background image, but if you have multiple directories, make sure each has the same set of images (i.e. either all or none have bg*.spraw, and all or none have fg*.spraw). Also avoid directories without .spraw files.

Note: to save about 256 KiB of precious ram, make sure to set the lock screen background (in the original settings app, Theme & Background -> Start Screen) to an image with an exact size of 1024x512 (the content doesn't matter, it will be replaced by the plugin anyway). If you did it right, you should have a file named ur0:shell/wallpaper/lock.dds with a size of 256.12 KB in VitaShell (262272 bytes, to be precise).

Image creation details

The vita has a screen resolution of 960x544, but the status bar at the top of your screen is opaque, so you only have 960x512 pixels for the actual image contents. But due to the limitations of the Vita, you need to specify a texture with size 1024x512, and it will be scaled back to 960x512 by the Vita. If you use the convert tool it will handle all of this automatically, but if you have an input image with a different aspect ratio than 15:8, it will crop it.

If you need more control over the creation of the image, here are the steps you should take (this assumes you use gimp, but other image editors should work too):

1. Select "Rectangle Select Tool" (R), select Fixed Aspect ratio and set aspect ratio to 15:8.
2. Select the region of the image you want to use.
3. Image -> Crop to selection
4. Image -> Scale Image, and scale it to 1024x512.

At this point you can export the image to a png and convert it to spraw with convert --no-scale. (--no-scale is important, otherwise it will take the middle 960x512 of your image and scale it again.)

Alternatively, you can use DDS images directly. Make sure you set compression format to DXT1 and no mipmap. The skinpeel plugin will be able to load .dds files created this way directly, but it will be a tinly little bit slower.

Convert tool

You need a c++ compiler to compile it. Running compile_convert.sh on linux should produce an executable called convert, on other OS you might need to tweak it. It can load any images that stb_image can load (jpg, png, tga, bmp, gif, pic, pnm, and maybe psd, hdr).

It can either convert a bunch of image files in one go (in this case the output file will be the input file but with the extension replaced with .spraw), or a single file with a custom output name (specified with -o).

Usage: ./convert [options] input_files
 -h --help: print help
 -v --verbose: verbose
 -s --no-scale: do not scale input, it must be already 1024x512
 -f --filter=FILTER: specify scale filter (default, box, triangle, cubic-b-spline, catmull-rom, mitchell)
 -q --quality=QUALITY: specify DXT1 compress quality (0..9, 9 is the best)
 -o --out=FILE: specify output filename

Compile Vita plugin

Make sure you have VitaSDK installed. Note that I use version 1033 of the SDK, it might or might not work with newer versions.

If you have that, make sure the VITASDK environment variable is set to the correct value and execute ./compile.sh.

License

This program is free software. It comes without any warranty, to the extent permitted by applicable law. You can redistribute it and/or modify it under the terms of the Do What The Fuck You Want To Public License, Version 2, as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.

Original code written by me is licensed under WTFPL 2. The converter executable incorporates some third party code under permissive licenes:

• stb_image.h and stb_image_resize.h by stb. Public domain.
• icbc.h DXT1 encoder. MIT License.

The Vita plugin includes xoshiro128++ random number generator (public domain).