Problems with Qt when using catkin_make in ROS workspace

Question

I'm currently programming a Qt GUI to remote control a ROS-controlled robot. When using catkin_make in the catkin_ws I got the following error:

CMake Error at /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
  Could not find a package configuration file provided by "Qt5" with any of
  the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.
Call Stack (most recent call first):
  gui/CMakeLists.txt:31 (find_package)

I then tried to solve the error by putting set(Qt5_DIR /home/user/Qt/5.12.0/gcc_64/lib/cmake/Qt5) (which contains the Qt5Config.cmake) in the gui/CMakeLists.txt and got a new error:

CMake Error at /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
  Found package configuration file:

    /home/user/Qt/5.12.0/gcc_64/lib/cmake/Qt5/Qt5Config.cmake

  but it set Qt5_FOUND to FALSE so package "Qt5" is considered to be NOT
  FOUND.  Reason given by package:

  The Qt5 package requires at least one component

Call Stack (most recent call first):
  gui/CMakeLists.txt:33 (find_package)

Another Qt5Config.cmake is in /usr/lib/x86_64-linux-gnu/cmake/Qt5 though putting set(Qt5_DIR /usr/lib/x86_64-linux-gnu/cmake/Qt5) into the gui/CMakeLists.txt only leads to a similar error (just with a different path).

I'm kind of lost right now, maybe someone can point me to the right direction?

If it helps, I'm on Ubuntu 16.04.

Answer 1

Find Package Does More than just setting a path.

You can Add Path to the Qt folder in CMAKE_PREFIX_PATH to avoid it like this:

export CMAKE_PREFIX_PATH=$CMAKE_PREFIX_PATH:/home/user/Qt/5.12.0/gcc_64

or you can install qt binaries for ROS using apt-get Like This:

sudo apt-get install ros-kinetic-libqt-*