ClassicJems: C++/Qt J2ME & Symbian Desktop Emulator

ClassicJems is a high-performance desktop emulation platform for J2ME and Symbian mobile application archives, built natively using C++17 and the Qt6 framework. By combining UI view tracking and execution engines inside a single runtime ecosystem, it provides native instruction interpretation loops without garbage collection or intermediate translation lags.

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📁 1. Project Directory Structure

Layout of the folders and files in the repository:

classicjems/
├── CMakeLists.txt              # Unified build rules for Windows and Linux
├── README.md                   # Setup guide and compilation workflows
├── src/                        # Core C++ Application Source
│   ├── main.cpp                # App entry point initializing Qt
│   ├── mainwindow.h            # Main UI controller definitions
│   ├── mainwindow.cpp          # Stacked screen router & keyboard interceptor logic
│   ├── gamelibrarywidget.h     # Game Library grid view definitions
│   └── gamelibrarywidget.cpp   # Game Library drag-and-drop & search logic
└── third_party/                # Engine Submodule Repositories
    ├── eka2l1/                 # Symbian C++ emulation core (Submodule)
    └── freej2me/               # J2ME execution core (Submodule)

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🚀 2. Features

• Retro ROM Dashboard: A modern, dark-themed grid dashboard presenting available game titles grouped by platform.
• Drag-and-Drop Loader: Import games instantly by dragging .jar (J2ME) or .sis / .sisx (Symbian) files directly into the emulator dashboard.
• Incremental Search Indexer: Quickly filter game collections by typing in the search bar.
• Viewport Stack Routing: Switches viewports instantly from the dashboard to a fixed aspect ratio (450x800) OpenGL rendering viewport.
• Zero-Latency Keyboard Interception: Bypasses OS key-repeat delays to capture instantaneous button press and release states.

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🎮 3. Input Mappings & Controls

When playing games, your desktop system keyboard functions as a virtual mechanical keypad array mapped according to the following matrix rules:

• W / A / S / D (or Arrow Keys) -> Directional Navigational D-Pad (Up=1, Down=2, Left=3, Right=4)
• Z / Enter -> Primary Select / Center Trigger Key (Button A / KeyCode 5)
• X / Escape -> Clear Frame / Return Navigation (Button B / KeyCode 8)
• Q / E -> Left Soft Key (LSK = -6) / Right Soft Key (RSK = -7)
• Top Row 0 - 9 Keys -> Standard Numeric T9 input matrix overrides (0-9)
• F1 Key -> Exit active emulation and return to the Game Library launcher dashboard

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🛠️ 4. Compilation & Local Setup

🐧 Linux Environment Setup (Ubuntu/Debian)

Install core developer tool chains and the required library components directly via your system package manager:

sudo apt update
sudo apt install build-essential cmake qt6-base-dev qt6-declarative-dev libsdl2-dev

🪟 Windows Environment Setup

1. Download and install Visual Studio 2022 Community Edition (Ensure "Desktop development with C++" workspace tracking is checked).
2. Install CMake and verify it is mapped onto your global Windows environment system PATH variables.
3. Fetch dependencies cleanly via vcpkg:

git clone https://github.com/microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.bat
./vcpkg install qt6-base sdl2

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🚀 5. Execution Pipelines

To configure, build, and launch the executable workspace binary from your command terminal shell, run the following unified compile sequence:

# Generate build workspace tracking folder
mkdir build
cd build

# Configure project make vectors via CMake
# (Windows users: Append your target -DCMAKE_TOOLCHAIN_FILE variable pointing to vcpkg script)
cmake ..

# Compile the final native application executable payload
cmake --build . --config Release