Game Boy QR-Paint

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Overview

Draw on the Game Boy and share it direct to your phone using a QRCode! (without the internet!)

Features

• Share drawings as PNG images via QR Code
• Drawing tools: Pencil, Line, Eraser, Rectangle, Circle, Flood Fill
• Undo, Redo stack
• 3 Drawing Save slots
• Adjustable Draw Width
• Adjustable Draw speed (Fast, Medium, Slow, Pixel Step)
• 2 Draw colors (Black and White)

Usage

Button Controls:

• D-Pad: Move cursor (Arrow keys)
• A: Draws with tool (Z key)
• B: Cancel tool action / Teleport cursor between menu and drawing areas (X key)
• SELECT + UP/DOWN: Adjust Cursor Speed (Select + Up / Down Arrow keys)
• SELECT + LEFT/RIGHT: Adjust Drawing Width (Select + Left / Right Arrow keys)
• START: Create QRCode (Enter Key)

The cursor movement has a small amount of inertia while in the drawing areas. It will apply as long as some button is being held down, and resets to zero when all buttons are released. This helps with drawing curves using a D-Pad, which otherwise tends toward right angles and diagonals.

Sending to Mobile Phone

Scanners

Known working QRCode scanners:

• Android Binary Eye
• Android Camera (in scan mode)
• Web: https://scanqr.org

Known not working scanners:

• "Camera" app on some Samsung phones

Browsers

Known working Browsers: (via "share-to" or pasting in the url, not via the browser's own scanner)

• Firefox/Fennec Web Browser (Android mobile, Linux desktop)
• Chromium (Linux desktop)

Known not working Browsers:

• Chromium/Chrome (Android)

Techincal details

The drawing is limited to 96x96 monochrome pixels due to QRCode size limits and the current lack of PNG DEFLATE compression.

The process is:

• Convert: GB Drawing -> Indexed PNG -> Base64 Encode -> mime url -> QRCode
• Share to phone: QRCode -> Scanner app -> Share to Web Browser

The Emulator .sav files are PNGs!

 The .sav files generated by emulators for this ROM can be opened in many paint programs since the first cart SRAM bank contains an indexed PNG of the last drawing image that was exported as a QRCode.

Source Code and Tools Used

Open source on Github: https://github.com/bbbbbr/gameboy_qr_paint/

• GBDK-2020 (4.5.0+) 
• Emulicious
• ImHex
• The QRCode generator is an optimized fork of msx_qrcode: https://github.com/MartinezTorres/msx_qrcode/tree/master
  Which in turn is a fork of Nayuki's QR Code: https://github.com/nayuki/QR-Code-generator

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100% of donations go to support the itch.io platform. (details)