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Overview

Fake OS is a lightweight Windows desktop environment simulator written entirely in C using the native Win32 API and GDI (Graphics Device Interface). It demonstrates low-level systems programming by recreating the visual elements of a Windows operating system desktop — including gradient backgrounds, a dark taskbar, and a functional start menu.

Built without any external libraries or frameworks — just pure Windows API calls.

Features

• Gradient desktop — Multi-color gradient background rendered with GradientFill API
• Dark taskbar — Windows 11-style semi-transparent taskbar at the bottom
• Start menu — Functional start button with menu popup
• Window management — Basic window creation and event handling
• GDI rendering — All graphics drawn using native GDI functions
• Lightweight — Single C file, compiles to a small executable

Building

Prerequisites

• Windows OS (Win32 API is platform-specific)
• MSVC (Microsoft Visual C++ Compiler) or MinGW-w64
• Windows SDK (comes with MSVC)

Compile with MSVC

cl fake-os.c /Fe:fake-os.exe /link user32.lib gdi32.lib

Compile with MinGW-w64

gcc fake-os.c -o fake-os.exe -lgdi32 -luser32

Compile with Visual Studio (Developer Command Prompt)

cl.exe fake-os.c user32.lib gdi32.lib

Usage

Simply run the compiled executable:

fake-os.exe

The simulator window will appear with a gradient desktop background and taskbar.

Code Structure

fake-os.c          # Single source file — the entire simulator
├── WinMain()      # Application entry point
├── WndProc()      # Window procedure (event handler)
├── RenderDesktop() # GDI gradient background rendering
├── Taskbar drawing # Dark taskbar with start button
└── Start menu     # Popup menu implementation

Technical Details

• API: Win32 API (windows.h), GDI (GradientFill, CreateSolidBrush, etc.)
• Rendering: Double-buffered GDI rendering for smooth visuals
• Messaging: Standard Windows message loop with GetMessage/DispatchMessage
• Entry point: WinMain with proper window class registration

Why Fake OS?

This project was built to explore low-level Windows programming concepts:

• Understanding the Windows message loop and event-driven architecture
• Working directly with GDI for graphics rendering
• OS-like UI element implementation (taskbar, start menu)
• Systems programming without frameworks or libraries

Show Your Support

• ⭐ Star this repo — helps others discover it
• 🐛 Report issues — I respond within 24 hours
• 📬 Share feedback — contact@jaytechsoln.in
• ☕ Buy me a coffee — Sponsor

Made with ❤️ by Aswin Jay — part of JAY TECH SOLUTIONS

License

MIT License — see LICENSE for details.