Building Qt Bridge for C# from source

Building the NuGet Package and Test Application (Windows, .NET 8)

This guide documents the steps used to:

1. Build a minimal Qt 6 from source (subset of modules)
2. Build the Qt Bridge for C# (adapter, generator, rules)
3. Build/Run the test application against the local package

Prerequisites

• Visual Studio 2022 (Desktop development with C++) with the x64 Native Tools Command Prompt (required because Qt Bridge generates C++ code)
• .NET SDK 8+ (dotnet --version)
• Git
• CMake & Ninja (installed with VS; available in the native tools prompt)
• Python & Perl (required only if you build Qt from source) - see Qt's system requirements
• Sufficient disk space (Qt build can require tens of GB)

Using an existing Qt installation

If you already have a Qt 6 installation that includes qtbase, qtsvg, qtshadertools, qtdeclarative, qtquick3d, qtquick3dphysics, and qtquicktimeline, you can skip building Qt from source. In the x64 Native Tools Command Prompt for VS 2022, set QtInstallRoot to the Qt installation prefix (the folder that contains bin, lib, and include), then continue with Build the Qt Bridge for C#.

set QtInstallRoot=D:\Qt\6.11.0\msvc2022_64

Build Qt 6 (subset) from source

Open x64 Native Tools Command Prompt for VS 2022 and run:

# Choose a working directory
pushd D:\work

# Create source/build/install folders
mkdir qt6-source
mkdir qt6-build
mkdir qt6-install

# Clone Qt meta-repo (Qt 6 uses the qt5 meta-repo name)
git clone https://code.qt.io/qt/qt5.git qt6-source

# Initialize only the modules we need
cd qt6-source
init-repository --module-subset=qtbase,qtsvg,qtshadertools,qtdeclarative,qtquick3d,qtquick3dphysics,qtquicktimeline

# Configure out-of-source build
cd ..\qt6-build
..\qt6-source\configure -prefix ..\qt6-install -release -opensource -confirm-license -submodules qtbase,qtsvg,qtshadertools,qtdeclarative,qtquick3d,qtquick3dphysics,qtquicktimeline -- -DQT_BUILD_TESTS=OFF -DQT_BUILD_EXAMPLES=OFF

# Build and install
cmake --build .
cmake --install .

Notes

• You can add -DCMAKE_BUILD_PARALLEL_LEVEL=N to speed up builds (or use cmake --build . --parallel).
• If you run into generator issues, you can specify -G "Ninja" and install Ninja.
• The above turns off Qt tests/examples to keep the build lean.

Set Qt environment for the session

Use the same native tools prompt you used to build Qt:

set QtInstallRoot=D:\work\qt6-install

If you used an existing Qt installation, set QtInstallRoot to that path instead.

Build the Qt Bridge for C#

From the same prompt:

# Go to your Qt Bridge for C# source checkout
pushd D:\work\qtbridge-csharp

# Restore and build (Release)
dotnet build -c Release

Build the test app as a smoke test:

# Build the test app (adjust the path if different)
dotnet build -c Release examples\Primes\Primes.csproj

Test the package locally with the sample app

From the same prompt:

# Build & run the sample app
dotnet run --project examples\Primes\Primes.csproj -c Release

Troubleshooting

• MSVC/CMake not detected: Make sure you're using the x64 Native Tools prompt.
• Missing Python/Perl: Install them and ensure they're on PATH before running init-repository/configure.
• Long paths or spaces: Prefer short, space-free paths like D:\work.
• Rebuild from scratch: Delete the entire content of qt6-build and qt6-install directory and configure again.

What gets packaged

The NuGet contains:

• .NET adapter (host Qt/QML engine from C#)
• Generator (discovers your types and emits interop glue)
• Filtering rules (Include/Ignore/Exclude attributes)
• C++ include headers for the native bridge
• A minimal open-source Qt Quick runtime subset sufficient to run QML

All parts are versioned together to ensure compatibility.

Clean up

To revert environment changes, close the prompt or manually unset variables:

set QtInstallRoot=

After completing the steps above, you'll have:

• A locally built Qt install at %QtInstallRoot%
• A Release build of Qt Bridge for C#
• A NuGet package in nuget\local
• A test application built against that package