Prepis

This is a tool for cheating on exams that use a virtual camera. It hides a window behind the camera.

Supports image viewing and chatting through Discord.

It's meant for Windows, and it probably doesn't work (fully) on any other OS.

Installing

1. git clone git@github.com:Delemangi/prepis.git
2. cd prepis
3. npm install

Starting

1. npm run start

The terminal will remain on and frozen while running, so it's best to hide it on a different desktop (Windows Key + Tab).

Configuration

1. Create a config.json file in the project directory. It should have the following structure:

   {
       "token": "your_bot_token",
       "channels": [
           "discord_channel_id",
           "other_discord_channel_id"
       ],
       "modes": [
           "theory",
           "practical",
           "exercises"
       ],
       "x": 180,
       "y": 550,
       "width": 620,
       "height": 450
   }

   The x and y properties are the x and y offsets, respectively. The default values given here fit a one monitor 1080p setup.

2. Create an assets folder in the project directory, and create folders with any name for the image sets. Put all images in the corresponding folders. The folder names should be specified in the modes property in config.json.

3. For the PDF viewer, put a PDF file called test.pdf in the assets directory.

Chat

The chat feature requires a Discord bot. Create one here and put its token in the token property in config.json.

Invite the bot to a server and choose a text channel in which the bot listens for messages by coping its ID and adding it in the channels property in config.json.

Converting color images to grayscale

1. Put all images in the image-processor/input folder
2. python image_processor.py
3. Retrieve all images from image-processor/output

This may take a while to complete depending on the amount of images. It's supposed to make them less visible against a light background.

Window coordinates

Unfortunately there is no straightforward way to find the magic numbers, so you'll just have to try a few times until you're happy. The default configuration given above should be good for most cases.

For single 1080p monitor setups, the x setting should be 180. For dual 1080p monitor setups, the x settings should be 360.

Shortcuts

• Move to left image: a, left arrow
• Move to right image: d, right arrow
• Increase opacity (main window only): w, up arrow
• Decrease opacity (main window only): s, down arrow
• Increase opacity (PDF window only): alt + w
• Decrease opacity (PDF window only): alt + s
• Toggle visibility (main window only): escape
• Toggle visibility (PDF window only): shift + escape
• Switch tabs: m
• Send message: enter
• Toggle chat image visibility: b

Additionally, clicking any number will go to that image, i.e. clicking 1 will go to the first image. Holding ctrl while clicking a number will change to the respective mode instead.

The shortcuts for toggling visiblity work even when the windows are not focused. All other shortcuts require focus.

When starting the app, by default the main window is revealed and the PDF window is hidden.

Troubleshooting

In case something goes wrong, the %APPDATA%/prepis folder should be deleted.