OpenTrace ✏️

Observe. Extract. Create.
OpenTrace is a digital lightbox and tracing utility built for artists. It uses your device's camera as a background while overlaying reference images, allowing you to trace directly onto paper with perfect proportions.

[App Screenshot]

✨ Features

• 📸 Live Camera Background: Trace your digital reference directly onto your physical sketchbook using the device's rear camera.
• 🎛️ Image Processing: Instantly convert any image into Grayscale or a high-contrast Stencil to make tracing line-art drastically easier. Includes a threshold slider for fine-tuning detail.
• ✋ Infinite Gesture Engine: A custom-built multi-touch PanResponder that allows for flawlessly smooth dragging and massive pinch-to-zoom freedom (up to 4000%).
• 🔒 Canvas Lock: Instantly freeze your zoom and pan gestures so you don't accidentally move the reference image while drawing.
• 💡 Always Awake: A dedicated toggle to prevent your phone screen from dimming or turning off during long drawing sessions.
• 👁️ Zen Mode: Hide the entire user interface to maximize your drawing workspace.
• 🔄 Workspace Tools: Adjust image transparency on the fly, mirror/flip references, and rotate images with single-tap buttons.

🛠️ Tech Stack

• Framework: React Native
• Build System: Expo / EAS
• Key Packages:
  • expo-camera (Background view)
  • expo-image-picker (Gallery access)
  • expo-keep-awake (Screen lock)
  • react-native-webview (Hidden HTML5 Canvas for heavy image filtering)

🚀 How to Run Locally

If you want to clone this repository and run it on your own machine:

1. Install dependencies:

   npm install

Start the Expo server:

   npx expo start -c

Run on your phone: Scan the generated QR code using the Expo Go app on Android or iOS.

📦 Building the APK (Android) This project is configured to be built locally via Expo Application Services (EAS) without requiring a strict Git history. To build an installable .apk file for your phone:

set EAS_NO_VCS=1 && eas build -p android --profile preview

📥 Download the App

Download the latest Android APK here!

(Note: Your phone may ask you to allow installations from unknown sources, as this is an independent developer build.) Created as a personal utility to level up my drawing and coding skills!

Disclaimer: This is a fan-made, non-commercial open-source project. Any characters, artwork, or properties from Honkai: Star Rail used in the documentation or screenshots are the intellectual property of HoYoverse. This project is not affiliated with, endorsed by, or sponsored by HoYoverse.