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Configuring Qt5 OpenDDS Applications

Some applications included with OpenDDS require Qt5:

To build and use these applications, Qt5 must be available on the system and Qt5 support must be enabled in the build system.

Qt5

Qt5 is a framework primarily used for cross-platform GUI based applications. The Qt official website as of writing is qt.io. Qt can be downloaded prebuilt for all the major systems or as source code.

Also remember the options listed here are not the only ones. Any functional instance of Qt5 would work as long as it is built and has the headers and the basic Qt development tools (QtCreator is not required).

Getting Qt Using Package Managers

Many package managers have Qt development packages available:

Linux

  • qtbase5-dev on Debian-based systems
  • qt5-qtbase-devel on Fedora-based systems
  • qt5-base on Arch

macOS

Windows

The only package manager on Windows that appears to have a reliable Qt5 development package is vcpkg as qt5-base. There is a qt5 package that installs a complete Qt environment (including qt5-base), but this is overkill for what OpenDDS needs and is not required.

An important detail to note is that vcpkg requires a target architecture when installing a package which they call a "triplet". For 32-bit x86 Windows it is x86-windows which is the default and for 64-bit x86 Windows it is x64-windows. This must match the target architecture of OpenDDS.

To build Qt5 needed for 64-bit OpenDDS on 64-bit Windows:

vcpkg --triplet x64-windows install qt5-base

After that Qt root will be installed\x64-windows inside the root of vcpkg.

Also vcpkg works on Linux and macOS as well but building OpenDDS Qt applications with Qt5 built with vcpkg has not been tested on Linux and macOS.

Using the Configure Script

If using the configure script, Qt is enabled by using the --qt option. Other arguments required depend on how Qt was acquired and where it's located on the system.

Using a Qt Installed Through the System Package Manager

If you're using a standard Linux distro (Debian-based, Red Hat-based, etc.), and you want to use the system Qt (which is recommended), just supplying the --qt option should be enough and the configure script will take care of the rest. Should the configure script fail to recognize your Qt installation or the build fails due to missing Qt files, you might have to supply Qt parameters manually.

Manually Specifying Qt Locations

If Qt isn't in a standard place and/or isn't installed, then Qt paths have to be specified manually. You will need to supply the root of the Qt directory so the build system can find the Qt tools, libraries, and headers. The configure script has two options for Qt locations, --qt and --qt-include. If you built your Qt from source, --qt should be set to the root of the results or the install prefix. If headers were places some where other than include or include/qt5 of the root you have specified, you will need to also specify their location using --qt-include.

Qt Build Parameters

These are the options that can be passed to configure how Qt applications are built.

Env. Variable Description Configure Script Option Configure Script Default
QTDIR Qt Root Location --qt /usr
QT5_INCDIR Qt Header Location --qt-include QTDIR/include or QTDIR/include/qt5
QT5_BINDIR Qt Tools Location N/A QTDIR/bin
QT5_LIBDIR Qt Libraries Location N/A QTDIR/lib
QT5_SUFFIX Qt Tools Name Suffix N/A Blank or -qt5

vcpkg

The configure script will try to detect if vcpkg is being used. If there are no conflicts with manually supplied values, it sets QT5_BINDIR to QTDIR/tools/qt5. It will also set QT5_LIBDIR to QTDIR/debug/lib depending on if --debug option has been pass to configure.

Windows Example

configure --qt=C:\Qt\5.11.1\msvc2017_64

This is for a prebuilt 64-bit Qt 5.11.1 for Visual Studio 2017 using the official Qt Windows installer and the default location.

Without the Configure Script

It is possible to build OpenDDS without using the configure script, although this is not recommended unless one is familiar with OpenDDS and its build system, MPC. To enable Qt5 support the qt5 feature must be enabled (e.g. -features qt5=1) and environment variables must be set to configure the build to use Qt correctly:

Env. Variable Description MPC Default
QTDIR Qt Root Location N/A (Required)
QT5_INCDIR Qt Header Location QTDIR/include
QT5_BINDIR Qt Tools Location QTDIR/bin
QT5_LIBDIR Qt Libraries Location QTDIR/lib
QT5_SUFFIX Qt Tools Name Suffix Blank