WindowCaptureHider

WindowCaptureHider is a lightweight Windows DLL that hides top-level application windows from screen-capturing tools such as OBS, Snipping Tool, Microsoft Teams, Zoom, and others.
It uses the Windows API SetWindowDisplayAffinity to block these windows from being captured or recorded.

⚠️ Note: This repository serves as personal GitHub storage for development backup and archival purposes. While it is public and functional, it is not maintained as a full-scale production library. Users are welcome to fork or reuse the code as needed.

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📌 Table of Contents

1. Key Features
2. How It Works
3. Quick Start
4. Building From Source
5. Public API
6. Security & Limitations
7. Contributing
8. Roadmap
9. License

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✅ Key Features

Feature	Description
Universal capture-blocking	Automatically hides all top-level windows using WDA_EXCLUDEFROMCAPTURE.
Self-healing window loop	Re-enumerates windows every second to apply or remove capture-blocking.
Minimal footprint	No dependencies beyond Win32 API. ~150 lines of C++ code.
Auto start & stop	Starts on DLL load (DLL_PROCESS_ATTACH) and stops on unload.
Inject or load manually	Can be injected into any running process or loaded dynamically.
Multi-platform builds	Works on both x86 and x64. MSVC, Clang, and MinGW supported.
Personal GitHub Storage	Maintained as a personal development backup; not a user-configurable tool.

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🛠️ How It Works

1. EnumWindows gathers all top-level window handles.
2. Each window is set to WDA_EXCLUDEFROMCAPTURE using SetWindowDisplayAffinity.
3. Valid handles are stored in a set to track which ones are hidden.
4. Every second, a background thread updates the set: hiding new windows and removing destroyed ones.
5. Cleanup is performed when the DLL is unloaded or StopHidingWindows() is called.

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⚡ Quick Start

Option 1: Use Precompiled DLL

Download the latest version of WindowCaptureHider.dll from the Releases page.

Option 2: Inject or Load Manually

a) Inject via DLL Injector

injector.exe --pid <target-process-id> --dll WindowCaptureHider.dll

b) Load in Your Own Application

HMODULE hLib = LoadLibrary("WindowCaptureHider.dll");
// Starts automatically on load

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🔧 Building From Source

Requirements

• Visual Studio or MSVC Build Tools
• CMake (optional, for project generation)

Build Instructions

git clone https://github.com/myexistences/WindowCaptureHider.git
cd WindowCaptureHider
cl /LD WindowCaptureHider.cpp /Fe:WindowCaptureHider.dll

Or open WindowCaptureHider.sln in Visual Studio and build in Release/x64.

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📚 Public API

These two functions are exported by the DLL for manual control:

extern "C" __declspec(dllexport) void StartHidingWindows();
extern "C" __declspec(dllexport) void StopHidingWindows();

You can call them manually after loading the DLL to start or stop the hiding loop.

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🔒 Security & Limitations

• Windows may override WDA_EXCLUDEFROMCAPTURE in some environments (e.g. admin restrictions).
• This technique only hides windows from software-based screen capture, not from physical monitors or print screens.
• SetWindowDisplayAffinity only works on Windows 8 and above.

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🤝 Contributing

This project is primarily for personal use, but improvements or suggestions are welcome via pull requests or issues.

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📈 Roadmap

• Add window filtering by title/class (optional)
• GUI interface for selecting specific windows
• Log hidden windows in debug mode

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📄 License

This project is licensed under the GNU Affero General Public License v3.0 .