Building with Qt Creator

If you want to contribute a new feature or a bugfix to LibrePCB, the best way is to use Qt Creator. To get started, simply open the top-level CMakeLists.txt file with Qt Creator.

Configuring the Desktop Kit

When opening a project in Qt Creator for the first time, you need to configure the Desktop kit:

qtcreator_desktopkit

Click on the "Configure Project" button to get started.

Starting LibrePCB

Select the run configuration librepcb and click on the Run button:

qtcreator_run

Parallel Builds

If ninja is installed on your system, Qt Creator will use it by default, resulting in parallel builds (utilizing all your CPU cores) out of the box. If the fallback to GNU Make is being used, you may need to set make flags in order to achieve parallel builds.

Building on the Command Line

You can also build LibrePCB from the command line using cmake:

mkdir build && cd build
cmake ..
make -j8

Then run the librepcb binary in the build/apps/librepcb/ directory.

To install LibrePCB on your system, run make install.

Faster Rebuilds with ccache

If you regularly rebuild parts of LibrePCB, you can speed up that process by installing ccache and passing -DCMAKE_CXX_COMPILER_LAUNCHER=ccache to CMake.

cmake .. -DCMAKE_CXX_COMPILER_LAUNCHER=ccache

Choosing Qt Version

By default the used Qt version is automatically detected by CMake while Qt5 is preferred over Qt6. To explicitly specify the Qt version to use, set the CMake variable QT_MAJOR_VERSION to either 5 or 6:

cmake .. -DQT_MAJOR_VERSION=6

Please note that currently Qt6 support for LibrePCB is experimental and should not be used for official releases. However, we plan to make Qt6 the default soon (after more testing), and even removing Qt5 support (and thus also this CMake option) afterwards.

Changing the Install Prefix

By passing in the CMAKE_INSTALL_PREFIX parameter, you can change the install prefix. For example, if you want to install LibrePCB to /usr/local, use

cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local

Debug and Release Builds

By default CMake will create a release build without debug symbols.

To customize the build type, pass the CMAKE_BUILD_TYPE parameter to CMake. For example, to create a debug build:

cmake .. -DCMAKE_BUILD_TYPE=Debug

Available build types:

Debug: Debug build
Release: Standard release build
RelWithDebInfo: Release build with debug symbols
MinSizeRel: Release build optimized for minimal size

Compiler Warnings

By default, our own libraries and applications are compiled with -Wall. If you want to treat warnings as errors (advisable in CI, or before committing), pass the BUILD_DISALLOW_WARNINGS parameter to CMake:

cmake .. -DBUILD_DISALLOW_WARNINGS=1

Author Information

For investigating bug reports, it's useful to know where the application binary is coming from. Therefore this information can be compiled into the executable with the LIBREPCB_BUILD_AUTHOR parameter. Its value is then shown in the "About LibrePCB" dialog.

cmake .. -DLIBREPCB_BUILD_AUTHOR="Flathub Buildbot"

Shared Resources Path

The share directory contains icons, fonts, templates and more resources that LibrePCB needs at runtime. On a Linux system, it is usually located at /usr/share/librepcb.

By default (unless LIBREPCB_REPRODUCIBLE is set), the build process will embed the absolute path to the share directory located within the source tree into the binary. When starting LibrePCB, it will first check whether the binary is running from within CMAKE_BINARY_DIR. If that is the case, the share directory in the source tree will be used. Otherwise, LibrePCB will fall back to ../share/librepcb relative to the application binary.

This will work out-of-the-box in many cases. However, when packaging LibrePCB, you should explicitly set the share directory path (either an absolute or a relative path).

cmake .. -DLIBREPCB_SHARE=/usr/share/librepcb

Reproducible Builds

So far, LibrePCB does not officially support reproducible builds. However, we allow turning off some features that make the binary non-reproducible (like embedded source directory paths, or embedded git commit hashes). This should make it easier to achieve reproducible builds in the future.

cmake .. -DLIBREPCB_REPRODUCIBLE=1

OpenGL Utility Library (GLU) Dependency

The OpenGL Utility Library (GLU) is needed for the 3D viewer of LibrePCB and thus needs to be available both at built time and runtime. If this library is not available for a particular platform, it is possible to compile without it but the 3D viewer won't render all layers then.

cmake .. -DUSE_GLU=0

OpenCASCADE Dependency

Parts of the 3D features (e.g. reading/writing STEP files) depend on the OpenCASCADE library, also known as OCCT or OCE. As this library might not be available on any platform, or might lead to packaging issues, it is possible to build LibrePCB without these 3D features. The OpenCASCADE dependency is then not needed, while LibrePCB is still usable without any issues, just without full 3D support.

cmake .. -DUSE_OPENCASCADE=0

We recommend using the official OpenCASCADE library (OCCT), but generally LibrePCB should also work with the Community Edition (OCE). CMake should automatically detect the availability of both variants.

QtQuick / Qt Declarative / QML Dependency

Starting with version 1.0, LibrePCB depends on the QtQuick / Qt Declarative component for evaluation purposes. In future QML might be used for the GUI, but we first need to do some evaluation and testing. To catch potential issues as early as possible, the dependency has been added already but is not used yet for productive features. If this dependency causes any issues during packaging or during runtime, LibrePCB can currently be built without it:

cmake .. -DBUILD_QTQUICK_TEST=0

IMPORTANT: Please report any problems in our issue tracker! Otherwise, sooner or later the dependency might be mandatory without having a workaround anymore for your issue!

Dynamic Linking / Unbundling

By default, all dependencies except Qt and OpenCascade will be linked statically using vendored git submodules. If you prefer to unbundle some libraries, set the UNBUNDLE_xxx variable:

cmake .. -DUNBUNDLE_FONTOBENE_QT=1 -DUNBUNDLE_POLYCLIPPING=1

To unbundle all dependencies that support it, use -DUNBUNDLE_ALL=1.

Right now, the following libraries can be unbundled:

Library	Parameter	Search Methods
dxflib	`UNBUNDLE_DXFLIB`	`pkg-config`
fontobene-qt	`UNBUNDLE_FONTOBENE_QT`	`pkg-config`, `find_path`
googletest	`UNBUNDLE_GTEST`	`cmake`, `pkg-config`
hoedown ¹	`UNBUNDLE_HOEDOWN`	`pkg-config`
muparser	`UNBUNDLE_MUPARSER`	`cmake`, `pkg-config`
polyclipping	`UNBUNDLE_POLYCLIPPING`	`pkg-config`
quazip ²	`UNBUNDLE_QUAZIP`	`cmake`

¹ Note: Hoedown is only needed on Qt <5.14.
² Due to packaging issues with QuaZip 0.x, we only support QuaZip 1.x when unbundling. Using QuaZip 0.9 should work as well, but then you'll have to patch the cmake/FindQuaZip.cmake find script as well as potentially the include paths (quazip -> quazip5) yourself.

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