book-reader/README.md
Aryan c61a264a65
Pdf reflow rework (#51)
* perf(pdf): native Pdfium-based reflow engine with auto-open

Migrate PDF-to-Markdown reflow generation from PDFBox to a custom
native implementation using Pdfium. This transition improves
processing speed by ~10x and significantly reduces memory overhead.

- Native JNI Bridge: Implemented `pdfium_bridge.cpp` using `dlopen`
  to hook into the existing `libpdfium.so` memory space.
- Optimized Extraction: Replaced character-by-character JNI calls
  with bulk array retrieval (`getPageFontSizes`, `getPageFontWeights`),
  drastically reducing JNI boundary overhead.
- Enhanced Accuracy: Improved Markdown formatting logic by using
  native font weight (bold) and relative font size variance (headers).
- Thread Safety: Refactored generator to process pages sequentially
  while synchronized with the global `PdfiumCore.lock` to ensure
  stability across concurrent UI operations.
- Seamless UX: Implemented a reactive auto-open system in the
  PDF viewer that tracks user intent and navigates to the reflow
  view immediately upon background task completion.

* Improved PDF to Markdown conversion and added cache cleanup.

- Implemented automated cleanup of imported file caches when deleting books.
- Enhanced `PdfToMarkdownGenerator` with support for font flags (italics), improved kerning, and smarter paragraph wrapping.
- Updated `NativePdfiumBridge` and C++ JNI code to extract font information flags from PDFium.

* Implemented seamless file switching and enhanced reflow transition logic.

Key changes include:
- Added `switchToFileSeamlessly` to `MainViewModel` to handle state transitions and navigation when switching between PDF and reflowed text views.
- Updated `generateAndImportReflowFile` to support automatic opening of the generated file at a specific page/chapter.
- Integrated `NavigationEvent` and `CompletableDeferred` to manage asynchronous navigation and state updates during file switches.
- Modified `EpubReaderScreen` and `PdfViewerScreen` to pass the current position when toggling between PDF and text modes.
- Updated `AppNavigation` to move navigation logic out of the `NavHost` and added loading overlays to viewers to improve UI feedback during transitions.
2026-03-10 10:59:44 +05:30

90 lines
3.3 KiB
Markdown

<div align="center">
<h1>
<img src="docs/ICON.png" height="48" width="48" align="center" alt="Episteme Reader Icon"/>
<span>&nbsp;Episteme Reader</span>
</h1>
<p>A native Android document reader application built with Kotlin and Jetpack Compose.</p>
<a href="https://play.google.com/store/apps/details?id=com.aryan.reader">
<img alt="Get it on Google Play" src="https://play.google.com/intl/en_us/badges/static/images/badges/en_badge_web_generic.png" height="70"/>
</a>
</div>
<br/>
![Episteme Reader Preview](docs/EPISTEME.png)
## Overview
Episteme Reader is an offline-first application designed for reading various document formats. It leverages native Android technologies and C++ libraries to provide a performant reading experience with customization capabilities.
> **Note:** This is the Open Source (OSS) edition of Episteme Reader. The version available on the Google Play Store is built from this core but includes additional proprietary features.
## Features
### Supported Formats
* **Documents:** PDF
* **E-books:** EPUB, MOBI, AZW3
* **Text:** MD, TXT, HTML
### PDF Features
* **Viewing Modes:** Vertical Scroll and Paginated view.
* **Ink Annotations:** Draw directly on pages using Pen, Highlighter, and Eraser tools.
* **Text Annotations:** Add text notes anywhere on the page using system or custom fonts.
### E-Book Features
* **Parsing:** Native parsing for MOBI/AZW3 via `libmobi` and EPUB via `Jsoup`.
* **Customization:** Adjust font size, line spacing, and margins.
* **Custom Fonts:** Support for importing user-provided font files (`.ttf`, `.otf`).
### General
* **Text-to-Speech (TTS):** Read documents aloud using the system TTS engine.
* **File Management:** Built-in library organization.
## Architecture
* **UI:** 100% Jetpack Compose (Material3).
* **Architecture:** MVVM with Unidirectional Data Flow.
* **Database:** Room (SQLite) for metadata and annotations.
* **PDF Engine:** `pdfium-android` (Native PDFium bindings).
* **EPUB Engine:** Utilizes standard `WebView` for vertical scrolling mode, and a custom rendering engine for paginated mode.
* **Mobi Engine:** Custom JNI bindings to `libmobi`.
## Building from Source
1. **Clone the repository:**
```bash
git clone https://github.com/Aryan-Raj3112/episteme.git
cd episteme
```
2. **Build:**
Open in Android Studio and run the `ossDebug` variant.
```bash
./gradlew assembleOssDebug
```
## Open Source Libraries
This project is made possible by the Android open-source ecosystem:
* **Core & UI:** AndroidX, Jetpack Compose, Kotlinx Serialization
* **Document Engines:** PdfiumAndroidKt (PDF), libmobi (MOBI/AZW3), Google WOFF2 (Fonts)
* **Parsers:** Jsoup (HTML/EPUB), Flexmark (Markdown)
* **Media & Image Loading:** Coil, Media3 (ExoPlayer)
* **Utilities:** Room (Database), Timber (Logging)
## License
This project is licensed under the **GNU Affero General Public License v3.0 (AGPL-3.0)**. See the [LICENSE](LICENSE) file for details.
## Support
If you find Episteme Reader useful and want to support its development, please consider sponsoring. Thank you!
<a href="https://github.com/sponsors/Aryan-Raj3112">
<img src="https://img.shields.io/badge/Sponsor-%E2%9D%A4-%23db61a2?logo=github" alt="Sponsor on GitHub"/>
</a>