14.5. Building the CamCOPS client

The CamCOPS client is written in C++11 using the Qt cross-platform framework. We provide a custom python script to build Qt from source, along with its dependencies (OpenSSL, SQLCipher and FFmpeg). CamCOPS can then be compiled and linked with this custom version of Qt. This can be done within Qt Creator, which confusingly is bundled with a second, official distribution of Qt.

14.5.1. Prerequisites

Ensure the following prerequisites are met: https://wiki.qt.io/Building_Qt_6_from_Git

14.5.1.1. Linux

14.5.1.2. Android (with a Linux build host)

Todo

Maybe “Include prebuilt OpenSSL libraries” will simplify things?

14.5.1.3. Windows

  • Install a recent version of Python. Make sure it’s on your PATH.

  • Install a Microsoft Visual C++ compiler. A free one is Visual Studio Community. As you install Visual Studio, don’t forget to tick the C++ options.

  • Install these other tools. Many are available with Chocolatey.

  • Add everything to the PATH.

    • In Windows 10, persistent environment variable settings are accessible by searching the Start menu for “environment variables”, or Start ‣ Control Panel ‣ System and Security ‣ System ‣ Advanced System Settings ‣ Environment Variables.

    • You can use either the User or the System settings, as you see fit.

    • PATH elements are separated with semicolons, if you edit the path manually.

    • For example, you may want these:

      C:\tools\msys64
      C:\tools\msys64\usr\bin
      C:\Program Files\NASM
      C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build
      
      -- These are usually added automatically by installers:
      
      C:\Program Files\Git\cmd
      C:\ActiveTcl\bin
      C:\Perl64\bin
      
    • Do make sure that the PATH doesn’t have an unquoted ampersand in; this is technically legal but it causes no end of trouble (see build_qt.py). (The usual culprit is MySQL.) The build_qt.py script will check this.

  • Tested and as part of our continuous integration process on GitHub (see https://github.com/ucam-department-of-psychiatry/camcops/blob/master/.github/workflows/build-qt.yml ) and as of 2023-12-21: .. code-block:: none

    ActivePerl 5.28.1 build 2801 (64-bit) ActiveTcl 8.6.7 build 0 (64-bit) CCache 3.7.12 CMake 3.25.1 (64-bit) Microsoft Visual Studio Community 2019 MSYS2 20231026.0.0 NASM 2.14.02 (64-bit) Python 3.9.13 Qt Creator 4.10.1 Windows 10 (64-bit) Yasm 1.2.0

14.5.1.4. macOS (formerly OS X)

14.5.1.5. All operating systems

  • Install the open-source edition of Qt, with Qt Creator. (You only really need the Tools component. We will fetch Qt separately.)

  • Make sure you have Git installed.

  • Set some environment variables, so we can be consistent in these instructions. Specimen values:

    Environment variable

    Example value (Linux, MacOS)

    Example value (Windows)

    Notes

    CAMCOPS_QT6_BASE_DIR

    ~/dev/qt_local_build

    %USERPROFILE%\dev\qt_local_build

    Read by build_qt.py.

    CAMCOPS_SOURCE_DIR

    ~/dev/camcops

    %USERPROFILE%\dev\camcops

    Used in these instructions and by the Windows Inno Setup script.

    CAMCOPS_VENV

    ~/dev/camcops_venv

    %USERPROFILE%\dev\camcops_venv

    Used in these instructions.

    CAMCOPS_VISUAL_STUDIO_REDIST_ROOT

    N/A.

    C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Redist\MSVC\14.29.30133

    Used by the Windows Inno Setup script.

  • Fetch CamCOPS. For example, for the GitHub version:

    # Linux
    git clone https://github.com/ucam-department-of-psychiatry/camcops $CAMCOPS_SOURCE_DIR
    
    REM Windows
    git clone https://github.com/ucam-department-of-psychiatry/camcops %CAMCOPS_SOURCE_DIR%
    
  • Create a virtual environment and install some Python tools:

    # Linux
    python3 -m venv $CAMCOPS_VENV
    . $CAMCOPS_VENV/bin/activate
    pip install cardinal_pythonlib
    
    REM Windows
    python -m venv %CAMCOPS_VENV%
    %CAMCOPS_VENV%\Scripts\activate
    pip install cardinal_pythonlib
    

14.5.2. Build OpenSSL, SQLCipher, Qt

Build a copy of Qt and supporting tools (OpenSSL, SQLCipher, FFmpeg) from source using the CamCOPS build_qt.py tool (q.v.). For example:

# Linux
$CAMCOPS_SOURCE_DIR/tablet_qt/tools/build_qt.py --build_all
REM Windows
python %CAMCOPS_SOURCE_DIR%/tablet_qt/tools/build_qt.py --build_all

14.5.2.1. Version constraints for OpenSSL and SQLCipher

14.5.2.2. Troubleshooting build_qt

14.5.2.2.1. Problem: aarch64-linux-android-gcc-4.9: not found

You might see this when compiling for Android/64-bit ARM. The relevant arm64 cross-compiler is missing. See https://stackoverflow.com/questions/28565640/build-kernel-with-aarch64-linux-gnu-gcc and try e.g. sudo apt-get install gcc-aarch64-linux-gnu.

Todo

IN PROGRESS ARM64 sudo apt-get install gcc-4.9-aarch64-linux-gnu

14.5.3. Run and set up Qt Creator

  • Run Qt Creator.

  • If you are compiling for Android:

    • Configure your Android SDK/NDK and Java JDK at: Tools ‣ Options ‣ Android, or in newer versions of Qt Creator, Tools ‣ Options ‣ Devices ‣ Android ‣ Android Settings.

  • Proceed with the instructions below.

14.5.4. Qt versions

See Tools ‣ Options ‣ Kits ‣ Qt Versions, or on MacOS, see Qt Creator ‣ Preferences ‣ Kits ‣ Qt Versions.

Assuming you set your qt_local_build directory to ~/dev/qt_local_build, the build_qt.py script should have generated a series of qmake (or, under Windows, qmake.exe) files within that directory:

Operating system

qmake

Linux, x86 64-bit

qt_linux_x86_64_install/bin/qmake

Android, ARM 32-bit

qt_android_armv7_install/bin/qmake

Android, ARM 64-bit

qt_android_armv8_64_install/bin/qmake

Android emulator, x86 32-bit

qt_android_x86_32_install/bin/qmake

Mac OS/X, x86 64-bit

qt_osx_x86_64_install/bin/qmake

iOS, ARM 32-bit

qt_ios_armv7_install/bin/qmake

iOS, ARM 64-bit

qt_ios_armv8_64_install/bin/qmake

iOS Simulator, x86 64-bit

qt_ios_x86_64_install/bin/qmake

Windows, x86 32-bit

qt_windows_x86_32_install/bin/qmake

Windows, x86 64-bit

qt_windows_x86_64_install/bin/qmake

Select the correct qmake and it will be added as a Qt version. You can change its name (prefixing “Custom” may be helpful to recognize it).

14.5.5. Qt kits

See Tools ‣ Options ‣ Kits ‣ Kits, or on MacOS, see Qt Creator ‣ Preferences ‣ Kits ‣ Kits.

Note

If you did not install a version of Qt with Qt Creator, pick one of your own kits and choose “Make Default”. Otherwise you will get the error Could not find qmake spec 'default'. (e.g. in the General Messages tab when you open your application) and the .pro (project) file will not parse. See https://stackoverflow.com/questions/27524680.

Non-default options are marked in bold and/or as “[non-default]”.

Custom_Linux_x86_64

  • Last checked against Qt Creator 11.0.2 (built Aug 2023).

    Option

    Setting

    Name

    [non-default] Custom_Linux_x86_64

    File system name

    Run device type

    Desktop

    Run device

    Desktop (default for Desktop)

    Build device

    Desktop (default for Desktop)

    Sysroot

    Compiler: C

    GCC (C, x86 64bit in /usr/bin)

    Compiler: C++

    GCC (C++, x86 64bit in /usr/bin)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    System GDB at /usr/bin/gdb

    Qt version

    THE “LINUX 64-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    Additional Qbs Profile Settings

    CMake Tool

    System CMake at /usr/bin/cmake

    CMake generator

    [not editable: “Ninja”]

    CMake Configuration

    -DQT_QMAKE_EXECUTABLE:FILEPATH=%{Qt:qmakeExecutable} -DCMAKE_PREFIX_PATH:PATH=%{Qt:QT_INSTALL_PREFIX} -DCMAKE_C_COMPILER:FILEPATH=%{Compiler:Executable:C} -DCMAKE_CXX_COMPILER:FILEPATH=%{Compiler:Executable:Cxx}

Custom_Android_ARM32: 32-BIT configuration for clang

  • Last checked against Qt Creator 11.0.2 (built 12 Aug 2023) under Linux.

    Option

    Setting

    Name

    [non-default] Custom_Android_ARM32

    File system name

    Run device type

    Android Device

    Run device

    YOUR DEVICE

    Build device

    Desktop (default for Desktop)

    Sysroot

    Compiler: C

    Android Clang (C, arm, NDK 25.1.8937393)

    Compiler: C++

    Android Clang (C++, arm, NDK 25.1.8937393)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    Android Debugger (armeabi-v7a, NDK 25.1.8937393)

    Qt version

    THE “ANDROID, ARM 32-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    Additional Qbs Profile Settings

    CMake Tool

    CMake 3.24.2 (Qt)

    CMake Generator

    Ninja

    CMake Configuration

    -DQT_QMAKE_EXECUTABLE:FILEPATH=%{Qt:qmakeExecutable} -DCMAKE_PREFIX_PATH:PATH=%{Qt:QT_INSTALL_PREFIX} -DCMAKE_C_COMPILER:FILEPATH=%{Compiler:Executable:C} -DCMAKE_CXX_COMPILER:FILEPATH=%{Compiler:Executable:Cxx}

Custom_Android_ARM64

  • Last checked against Qt Creator 11.0.2 (built 12 Aug 2023) under Linux.

    Option

    Setting

    Name

    [non-default] Custom_Android_ARM64

    File system name

    Run device type

    Android Device

    Run device

    YOUR DEVICE

    Build device

    Desktop (default for Desktop)

    Sysroot

    Compiler: C

    Android Clang (C, aarch64, NDK 25.1.8937393)

    Compiler: C++

    Android Clang (C++, aarch64, NDK 25.1.8937393)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    Android Debugger (arm64-v8a, NDK 25.1.8937393)

    Qt version

    THE “ANDROID, ARM 64-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    Additional Qbs Profile Settings

    CMake Tool

    CMake 3.24.2 (Qt)

    CMake Generator

    Ninja

    CMake Configuration

    -DQT_QMAKE_EXECUTABLE:FILEPATH=%{Qt:qmakeExecutable} -DCMAKE_PREFIX_PATH:PATH=%{Qt:QT_INSTALL_PREFIX} -DCMAKE_C_COMPILER:FILEPATH=%{Compiler:Executable:C} -DCMAKE_CXX_COMPILER:FILEPATH=%{Compiler:Executable:Cxx}

Custom_Android_x86 – NOT FULLY TESTED

Option

Setting

Name

[non-default] Custom_Android_x86

File system name

Device type

Android Device

Device

Run on Android (default for Android)

Sysroot

Compiler: C

<No compiler>

Compiler: C++

Android GCC (i686-4.9)

Environment

[not editable: “No changes to apply.”]

Debugger

Android Debugger for Android GCC (i686-4.9)

Qt version

THE “ANDROID EMULATOR” ONE FROM QT VERSIONS, ABOVE

Qt mkspec

CMake Tool

System CMake at /usr/bin/cmake

CMake Generator

CodeBlocks - Unix Makefiles

CMake Configuration

[not editable]

Additional Qbs Profile Settings

Custom_Windows_x86_64

  • Last checked against Qt Creator 4.8.1 (built Jan 2019).

    Option

    Setting

    Name

    [non-default] Custom_Windows_x86_64

    File system name

    Device type

    Desktop

    Device

    Local PC (default for Desktop)

    Sysroot

    [non-default] [...]\qt_local_build\qt_windows_x86_64_install\bin

    Compiler: C

    Microsoft Visual C++ Compiler 14.0 (amd64)

    Compiler: C++

    Microsoft Visual C++ Compiler 14.0 (amd64)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    Auto-detected CDB at C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\cdb.exe

    Qt version

    THE “WINDOWS 64-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    CMake Tool

    System CMake at C:\Program Files (x86)\CMake\bin\cmake.exe

    CMake Generator

    CodeBlocks - MinGW Makefiles, Platform: <none>, Toolset: <none>

    CMake Configuration

    CMAKE_CXX_COMPILER:STRING=%{Compiler:Executable:Cxx} CMAKE_C_COMPILER:STRING=%{Compiler:Executable:C} CMAKE_PREFIX_PATH:STRING=%{Qt:QT_INSTALL_PREFIX} QT_QMAKE_EXECUTABLE:STRING=%{Qt:qmakeExecutable}

    Additional Qbs Profile Settings

Also works with: CMake Generator = CodeBlocks - NMake Makefiles JOM, Platform: <none>, Toolset: <none>.

Custom_Windows_x86_32

  • Last checked against Qt Creator 4.8.1 (built Jan 2019).

    Option

    Setting

    Name

    ``Custom_Windows_x86_32``

    File system name

    Device type

    Desktop

    Device

    Local PC (default for Desktop)

    Sysroot

    [non-default] [...]\qt_local_build\qt_windows_x86_32_install\bin

    Compiler: C

    Microsoft Visual C++ Compiler 14.0 (amd64_x86)

    Compiler: C++

    Microsoft Visual C++ Compiler 14.0 (amd64_x86)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    None

    Qt version

    THE “WINDOWS 32-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    CMake Tool

    System CMake at C:\Program Files (x86)\CMake\bin\cmake.exe

    CMake Generator

    CMake Configuration

    CMAKE_CXX_COMPILER:STRING=%{Compiler:Executable:Cxx} CMAKE_C_COMPILER:STRING=%{Compiler:Executable:C} CMAKE_PREFIX_PATH:STRING=%{Qt:QT_INSTALL_PREFIX} QT_QMAKE_EXECUTABLE:STRING=%{Qt:qmakeExecutable}

    Additional Qbs Profile Settings

Note

For the Microsoft Visual C++ compiler, amd64 means 64-bit and x86 means 32-bit. Then the two-part options are cross-compilers, in which the first part is the type of the host machine (the one running the compiler) and the second part is the type of the destination machine (the one that will run the compiled executable). Therefore, in full, x86 produces 32-bit output using a 32-bit compiler; amd64 produces 64-bit output using a 64-bit compiler (i.e. requiring a 64-bit computer to do the compiling); x86_amd64 produces 64-bit output using a 32-bit compiler (so you can build for 64-bit machines using a 32-bit machine), and amd64_x86 produces 32-bit output using a 64-bit compiler. So, if you have a 64-bit machine, you probably want to use amd64_x86 and amd64; if you have a 32-bit machine, you definitely want to use x86 and x86_amd64.

Custom_MacOS_x86_64

  • Last checked against Qt Creator 11.0.3 (built 27 Sep 2023).

    Option

    Setting

    Name

    [non-default] Custom_MacOS_x86_64

    File system name

    Run device type

    Desktop

    Run device

    Desktop (default for Desktop)

    Build device

    Desktop (default for Desktop)

    Sysroot

    Compiler: C

    Clang (C, x86 64bit in /usr/bin)

    Compiler: C++

    Clang (C++, x86 64bit in /usr/bin)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    System LLDB at /usr/bin/ldb

    Qt version

    THE “MACOS 64-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    Additional Qbs Profile Settings

    CMake Tool

    System CMake at /usr/local/bin/cmake

    CMake Generator

    Ninja

    CMake Configuration

    CMAKE_CXX_COMPILER:STRING=%{Compiler:Executable:Cxx} CMAKE_C_COMPILER:STRING=%{Compiler:Executable:C} CMAKE_PREFIX_PATH:STRING=%{Qt:QT_INSTALL_PREFIX} QT_QMAKE_EXECUTABLE:STRING=%{Qt:qmakeExecutable}

Custom_iOS_armv8_64

  • Last checked against Qt Creator 11.0.3 (built 27 Sep 2023).

    Option

    Setting

    Name

    [non-default] Custom_iOS_armv8_64

    File system name

    Run device type

    iOS device

    Run device

    YOUR DEVICE

    Build device

    Desktop (default for Desktop)

    Sysroot

    Compiler: C

    Apple Clang (arm64)

    Compiler: C++

    Apple Clang (arm64)

    Environment

    [not editable: “No changes to apply.”]

    Debugger

    System LLDB at /usr/bin/lldb

    Qt version

    THE “iOS 64-BIT” ONE FROM QT VERSIONS, ABOVE

    Qt mkspec

    Additional Qbs Profile Settings

    CMake Tool

    System CMake at /usr/local/bin/cmake

    CMake Generator

    Xcode

    CMake Configuration

    -DQT_QMAKE_EXECUTABLE:FILEPATH=%{Qt:qmakeExecutable} -DCMAKE_PREFIX_PATH:PATH=%{Qt:QT_INSTALL_PREFIX} -DCMAKE_C_COMPILER:FILEPATH=%{Compiler:Executable:C} -DCMAKE_CXX_COMPILER:FILEPATH=%{Compiler:Executable:Cxx}

If Qt accept the settings, a section marked “iOS Settings” will appear in the “Build Settings” part of your project when configured for this kit.

Custom_iOS_Simulator_x86_64

Option

Setting

Name

[non-default] Custom_iOS_Simulator_x86_64

File system name

Device type

iOS Simulator

Device

iOS Simulator (default for iOS Simulator)

Sysroot

[non-default] /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk

Compiler: C

Apple Clang (x86_64)

Compiler: C++

Apple Clang (x86_64)

Environment

[not editable: “No changes to apply.”]

Debugger

System LLDB at /Applications/Xcode.app/Contents/Developer/usr/bin/lldb

Qt version

THE “iOS SIMULATOR 64-BIT” ONE FROM QT VERSIONS, ABOVE

Qt mkspec

Additional Qbs Profile Settings

CMake Tool

System CMake at /usr/local/bin/cmake

CMake Generator

CodeBlocks - Unix Makefiles, Platform: <none>, Toolset: <none>

CMake Configuration

CMAKE_CXX_COMPILER:STRING=%{Compiler:Executable:Cxx} CMAKE_C_COMPILER:STRING=%{Compiler:Executable:C} CMAKE_PREFIX_PATH:STRING=%{Qt:QT_INSTALL_PREFIX} QT_QMAKE_EXECUTABLE:STRING=%{Qt:qmakeExecutable}

If Qt accept the settings, a section marked “iOS Settings” will appear in the “Build Settings” part of your project when configured for this kit.

14.5.6. Build settings

14.5.6.1. Android

Under Project ‣ Build Settings ‣ Build Steps ‣ Build Android APK:

Option

Setting

Application ‣ Android build platform SDK

android-33 [= default].

Sign package ‣ Keystore

~/Documents/CamCOPS/android_keystore/CAMCOPS_ANDROID_KEYSTORE.keystore [NB not part of published code, obviously!]

Sign package ‣ Sign package

Yes (at least for release versions)

Additional libraries

~/dev/qt6_local_build/openssl_android_armv8_64_build/openssl-3.0.12/libcrypto_3.so ~/dev/qt6_local_build/openssl_android_armv7_build/openssl-3.0.12/libssl_3.so

If you run this without a keystore, it produces a debug build (e.g. QtApp-debug.apk). If you run it with a keystore/signature, it produces android-build-release-signed.apk (formerly QtApp-release-signed.apk). The APK filename is fixed at this point (https://forum.qt.io/topic/43329/qt-5-3-1-qtcreator-rename-qtapp-debug-apk-to-myapp). We can rename the APK if we want, or just upload to Google Play, distribute, etc.

Qt will forget your “sign package” choice from time to time; get back to it via Projects ‣ [Custom Android ARM or whatever you called it] ‣ Build Android APK ‣ Sign package.

14.5.6.2. iOS

See:

It is possible to deploy to an actual device via USB or the iOS simulator using a development provisioning profile associated with an Apple developer ID. You need to enable developer mode on the device.

Some build/deploy problems can be solved by restarting Qt Creator, XCode and any running iOS simulator but check the error messages in Qt Creator first.

14.5.7. MacOS

See:

14.5.7.1. General

(I’d like to put general settings in a camcops.pro.shared file, as per http://doc.qt.io/qtcreator/creator-sharing-project-settings.html, but this isn’t working well at present.)

  • Open the camcops.pro project file in Qt Creator.

  • Add your chosen kit(s) to the CamCOPS project.

  • Use defaults, except everywhere you see Build Settings ‣ Build Steps ‣ Make ‣ Make arguments, add -j 8 for an 8-CPU machine to get it compiling in parallel.

  • Build.

Once built, see Releasing CamCOPS.

14.5.8. Notes

14.5.8.1. Debugging

  • DON’T FORGET to set up both Debug and Release (+/- Profile) builds.

  • Phone USB debugging negotiation sometimes takes a while. On the Samsung Galaxy phone, the alert light goes red when in Debug mode.

  • If a USB Android device appears not to connect (via adb devices), appears then disappears as you connect it (via lsusb | wc), and gives the dmesg error device descriptor read/64, error -71 or similar, try a different cable (see https://stackoverflow.com/questions/9544557/debian-device-descriptor-read-64-error-71); try also plugging it directly into the computer’s USB ports rather than through a hub.

  • If you lose the debugger windows in Qt Creator midway through a debug session, press Ctrl-4.

  • This error (with a variety of compiler names):

    .../mkspecs/features/toolchain.prf(50): system(execute) requires one or two arguments.
    Project ERROR: Cannot run compiler 'g++'. Maybe you forgot to setup the environment?
    

    means that you need to re-run qmake manually. It usually occurs if you delete your build* directories.

  • For debugging, consider install Valgrind: sudo apt install valgrind

14.5.8.2. Android debugging

  • Android logs

    • The default Android log format from adb logcat is explained at https://developer.android.com/studio/debug/am-logcat.html. That format is

      date time PID-TID/package priority/tag: message
      e.g.
      12-10 13:02:50.071 1901-4229/com.google.android.gms V/AuthZen: Handling delegate intent.
      
      but actually looks like
      
      06-18 23:47:48.731 28303 28344 E         : dlsym failed: undefined symbol: main
      06-18 23:47:48.731 28303 28344 E         : Could not find main method
      
    • So do:

    • Search for “Force finishing activity”.

  • Better, though, is to launch from Qt Creator, which automatically filters (and does so very well).

14.5.8.3. Troubleshooting qmake/compilation

  • Sometimes you have to restart Qt creator after creating new build settings; it loses its .pro file and won’t show the project, or complains of a missing .pro file when you try to build.

  • The first build can be very slow as it compiles all the resources; this usually looks like a process stuck compiling qrc_camcops.cpp to qrc_camcops.o

  • If builds are very slow, you may have forgotten to use all your CPU cores; try e.g. -j 8 (for 8 cores) as an argument to make, as above.

  • If an Android build fails for a bizarre reason (like garbage in a .java file that looks like it’s been pre-supplied), delete the whole build directory, which is not always removed by cleaning.

  • Error: "unsupported_android_version" is not translated: see https://bugreports.qt.io/browse/QTBUG-63952. This error does not prevent you from continuing.

  • This error whilst building CamCOPS:

    /home/rudolf/dev/qt_local_build/qt_linux_x86_64_install/bin/qmlimportscanner:
    error while loading shared libraries: libicui18n.so.55: cannot open shared
    object file: No such file or directory
    /home/rudolf/dev/qt_local_build/qt_linux_x86_64_install/mkspecs/features/qt.prf:312:
    Error parsing JSON at 1:1: illegal value
    Project ERROR: Failed to parse qmlimportscanner output.
    

    … occurred after an upgrade from Ubuntu 16.04 to 18.04; the problem relates to missing OS libraries (libicu); the easiest thing is to rebuild Qt.

  • This error whilst building CamCOPS:

    /usr/bin/x86_64-linux-gnu-ld: cannot find -ludev
    Makefile:2433: recipe for target 'camcops' failed
    collect2: error: ld returned 1 exit status
    

    … use sudo apt install libudev-dev.

  • This error whilst building CamCOPS under Windows 10:

    :-1: error: dependent
    'C:\Users\rudol\dev\qt_local_build\qt_windows_x86_64_install\lib\Qt5MultimediaWidgetsd.lib'
    does not exist.
    

    Try switching from “debug” to “release” build.

  • Missing header files or libraries under Ubuntu/Debian Linux:

    • For example, for the error “cannot find -lgstphotography-1.0”, try apt-file search gstphotography, or apt-file search gstphotography-1.0.so if you get too many results. Prefer packages with a -dev suffix as these have development headers.

    • Likewise, for the error “GL/gl.h: No such file or directory”, try apt-file search GL/gl.h. (Here the missing package is libgl-dev.)

14.5.8.4. Troubleshooting running CamCOPS

  • Runtime error, failing to find libssl.so or libcrypto.so:

    Starting /.../camcops...
    /.../camcops: error while loading shared libraries: libssl.so: cannot open shared object file: No such file or directory
    /.../camcops exited with code 127
    

    CamCOPS needs the libssl.so and libcrypto.so that was built by build_qt.py. Until we have a proper Linux client distribution, do this:

    $ export LD_LIBRARY_PATH=~/dev/qt_local_build/openssl_linux_x86_64_build/openssl-1.1.0g/
    

    … or wherever you built those .so libraries. Then re-run the CamCOPS .client.

  • This error whilst running CamCOPS (Ubuntu 18.04):

    Starting /.../camcops...
    /.../camcops: error while loading shared libraries: libOpenVG.so.1: cannot open shared object file: No such file or directory
    /.../camcops exited with code 127
    

    Thoughts:

    # Which files have similar names?
    
    $ find -L / -type f -name "libOpenVG.so*" 2>/dev/null
    /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1       # symlink to libOpenVG.so.1.0.0
    /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1.0.0   # actual file
    /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so         # symlink to libOpenVG.so.1.0.0
    /usr/lib/x86_64-linux-gnu/libOpenVG.so                  # symlink to mesa-egl/libOpenVG.so
    
    # Which packages provide these files?
    
    $ dpkg --search libOpenVG
    libopenvg1-mesa:amd64: /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1.0.0
    libopenvg1-mesa-dev: /usr/lib/x86_64-linux-gnu/libOpenVG.so
    libopenvg1-mesa-dev: /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so
    libopenvg1-mesa:amd64: /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1
    
    # Ergo, the problem can be solved with:
    
    $ sudo ln -s /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1 /usr/lib/x86_64-linux-gnu/libOpenVG.so.1
    
    # Yup, that fixes it.
    

    Solution:

    sudo ln -s /usr/lib/x86_64-linux-gnu/mesa-egl/libOpenVG.so.1 /usr/lib/x86_64-linux-gnu/libOpenVG.so.1