libwcap

libwcap is a small C++ library that lets you capture the screen, a window or any GStreamer‑compatible source on Linux. It relies on the freedesktop.org ScreenCast portal and GStreamer to pull raw frames from the compositor.

The project is intentionally lightweight and has no runtime dependencies other than the system libraries it links against.

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Features

• Capture the whole screen, a single window or any source the user selects.
• Retrieve frames as a std::vector<uint8_t> in BGR format.
• Very small public API – just a handful of classes and enums.
• Example program examples/simple_grab.cpp demonstrates the usage.

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Requirements

• C++17 compiler (clang, gcc, MSVC)
• CMake 3.10 or newer
• GStreamer 1.0 development packages
• libgio‑2.0 / libglib‑2.0 development packages
• pkg‑config

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Building

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release && cmake --build build -j

The build produces:

• libwcap.so – the shared library
• example_simple – a tiny demo program in examples/

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Usage

The public header is include/wcap.hpp. A minimal example is provided in examples/simple_grab.cpp.

Compile the example (already built by the CMake target example_simple):

./build/example_simple

Run it and answer the prompt to choose the capture type. The program will capture 100 frames and save the last frame as snapshot.png.

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API Overview

namespace wcap {
    enum class CaptureType { Screen, Window, Any };
    struct Frame {
        int width = 0;
        int height = 0;
        std::vector<uint8_t> data; // BGR, 3 bytes per pixel
    };

    class ScreenCapture {
    public:
        ScreenCapture();
        ~ScreenCapture();
        bool select_source(CaptureType type); // initialise capture
        Frame get_frame();                    // pull next frame
        void stop();                          // stop the pipeline
    };
}

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License

Apache-2.0 – see the LICENSE file.

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Contributing

Feel free to open issues or submit pull requests.