13.4. Building the CamCOPS client

The CamCOPS client is written in C++11 using the Qt cross-platform framework.

13.4.1. Prerequisites

Ensure the following prerequisites are met: https://wiki.qt.io/Building_Qt_5_from_Git

13.4.1.1. Linux

  • Linux should come with Python and the necessary build tools.

  • Tested in Aug 2018 with:

    Ubuntu 16.04
    Ubuntu 18.04 / gcc 7.3.0
    

13.4.1.2. Android (with a Linux build host)

13.4.1.3. 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:

  • 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:\cygwin64\bin
      C:\Program Files\NASM
      C:\Program Files (x86)\Microsoft Visual Studio\2017\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 in July 2018 with:

    ActivePerl 5.24.3 build 2404 (64-bit)
    ActiveTcl 8.6.7 build 0 (64-bit)
    CMake 3.12.0 (64-bit)
    Cygwin Setup 2.889 (64-bit)
    Microsoft Visual Studio Community 2017
    NASM 2.13.03 (64-bit)
    Python 3.6
    Qt Creator 4.7.0
    Windows 10 (64-bit)
    

13.4.1.4. macOS (formerly OS X)

13.4.1.5. 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_QT_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\2017\Community\VC\Redist\MSVC\14.14.26405

    Used by the Windows Inno Setup script.

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

    # Linux
    git clone https://github.com/RudolfCardinal/camcops $CAMCOPS_SOURCE_DIR
    
    REM Windows
    git clone https://github.com/RudolfCardinal/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
    

13.4.2. Build OpenSSL, SQLCipher, Qt

Build a copy of Qt and supporting tools (OpenSSL, SQLCipher) 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

13.4.2.1. Version constraints for OpenSSL and SQLCipher

13.4.2.2. Troubleshooting build_qt

13.4.2.2.1. Problem: tar fails to work under Windows

===============================================================================
WORKING DIRECTORY: C:\Users\rudol\dev\qt_local_build\src\qt5
PYTHON ARGS: ['tar', '-x', '-z', '--force-local', '-f', 'C:\\Users\\rudol\\dev\\qt_local_build\\src\\eigen\\eigen-3.3.3.tar.gz', '-C', 'C:\\Users\\rudol\\dev\\qt_local_build\\eigen']
COMMAND: tar -x -z --force-local -f C:\Users\rudol\dev\qt_local_build\src\eigen\eigen-3.3.3.tar.gz -C C:\Users\rudol\dev\qt_local_build\eigen
===============================================================================
tar: C\:\\Users\rudol\\dev\\qt_local_build\\eigen: Cannot open: No such file or directory

“How stupid,” you might think. And the command works without the -C C:\... option (i.e. the -f parameter is happy with a full Windows path, but -C or its equivalent -directory=... isn’t). This is with GNU tar v1.29 via Cygwin.

Fixed by using cardinal_pythonlib==1.0.46 and the chdir_via_python=True argument to untar_to_directory.

13.4.2.2.2. Problem: CL.EXE cannot open program database

Problem (Windows): fatal error C1041: cannot open program database '...\openssl-1.1.0g\app.pdb'; if multiple CL.EXE write to the same .PDB file, please use /FS

… even when -FS is in use via jom.

Solution: just run build_qt.py again; this error usually goes away. Presumably the Qt jom tool doesn’t always get things quite right with Visual C++, and this error reflects parallel compilation processes clashing occasionally. It’s definitely worth persisting, because Jom saves no end of time.

If it fails repeatedly, add the --nparallel 1 option. (It seems to be the OpenSSL build that’s prone to failing; you can always interrupt the program after OpenSSL has finished, and use the full number of CPU cores for the much longer Qt build.)

13.4.2.2.3. 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

13.4.3. 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.

13.4.4. 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).

13.4.5. Qt kits

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

Options last checked against Qt Creator 4.6.2 (built June 2018), then 4.8.1 (built Jan 2019) under Linux/Windows and 4.9.0 (built 11 Apr 2019) under MacOS.

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

Option

Setting

Name

[non-default] Custom_Linux_x86_64

File system name

Device type

Desktop

Device

Local PC (default for Desktop)

Sysroot

Compiler: C

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

Compiler: C++

GCC (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

CMake Tool

System CMake at /usr/bin/cmake

CMake Generator

CodeBlocks - Unix Makefiles

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

OLD_Custom_Android_ARM: DEPRECATED 32-BIT CONFIGURATION FOR GCC

Option

Setting

Name

[non-default] OLD_Custom_Android_ARM

File system name

Device type

Android Device

Device

Run on Android (default for Android)

Sysroot

Compiler: C

<No compiler>

Compiler: C++

Android GCC (C++, arm-4.9) 1

Environment

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

Debugger

Android Debugger for Android GCC (C++, arm-4.9) 1

Qt version

THE “ANDROID” 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_Android_ARM32: current 32-BIT configuration for clang

Note

If you have not set up your Android NDK (see above), the “Qt Versions” tab will report “No compiler can produce code for this Qt version. Please define one or more compilers for: arm-linux-android-elf-32bit”.

Option

Setting

Name

[non-default] Custom_Android_ARM32

File system name

Device type

Android Device

Device

Run on Android (default for Android)

Sysroot

Compiler: C

Android Clang (C, arm)

Compiler: C++

Android Clang (C++, arm)

Environment

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

Debugger

Android Debugger for Android Clang (C++, arm)

Qt version

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

Qt mkspec

CMake Tool

System CMake at /usr/bin/cmake

CMake Generator

CodeBlocks - Unix Makefiles

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

Custom_Android_ARM64

Option

Setting

Name

[non-default] Custom_Android_ARM64

File system name

Device type

Android Device

Device

Run on Android (default for Android)

Sysroot

Compiler: C

Android Clang (C, aarch64)

Compiler: C++

Android Clang (C++, aarch64)

Environment

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

Debugger

Android Debugger for Android Clang (C++, arm)

Qt version

THE “ANDROID, ARM 64-BIT” 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_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

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

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

Option

Setting

Name

[non-default] Custom_MacOS_x86_64

File system name

Device type

Desktop

Device

Local PC (default for Desktop)

Sysroot

Compiler: C

GCC (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

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}

Additional Qbs Profile Settings

Custom_iOS_armv8_64

BEING TESTED

Option

Setting

Name

[non-default] Custom_iOS_armv8_64

File system name

Device type

iOS device

Device

Sysroot

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

Compiler: C

Apple Clang (arm64)

Compiler: C++

Apple Clang (arm64)

Environment

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

Debugger

System LLDB at /usr/bin/ldb

Qt version

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

Qt mkspec

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}

Additional Qbs Profile Settings

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

BEING TESTED

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

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

Qt mkspec

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}

Additional Qbs Profile Settings

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.

13.4.6. Build settings

13.4.6.1. Android

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

Option

Setting

Application ‣ Android build SDK

PREVIOUSLY: android-23 [= default]. NOW: android-28 [= 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)

Advanced actions ‣ Use Ministro service to install Qt

Do NOT tick. (Formerly, before 2018-06-25, this was Qt deployment ‣ Bundle Qt libraries in APK. The objective remains to bundle Qt, not to install it via Ministro.)

Additional libraries

~/dev/qt_local_build/openssl_android_armv7_build/openssl-1.1.0g/libcrypto.so ~/dev/qt_local_build/openssl_android_armv7_build/openssl-1.1.0g/libssl.so

Then in the file AndroidManifest.xml (which Qt Creator has a custom editor for):

Option

Setting

Package name

org.camcops.camcops

Version code

[integer; may as well use consecutive]

Version name

[string]

Minimum required SDK

API 23 (Android 6) (see changelog 2018)

Target SDK

API 28 (Android 9) = minimum required by Google Play Store as of 2019-11-01.

Application name

CamCOPS

Activity name

CamCOPS

Run

camcops

Application icon

[icon]

Include default permissions for Qt modules

[tick]

Include default features for Qt modules

[tick]

Boxes for other permissions

[no other specific permission requested]

But then you must also edit AndroidManifest.xml manually to include the line:

<meta-data android:name="android.app.load_local_libs" android:value="-- %%INSERT_LOCAL_LIBS%% --:lib/libssl.so:lib/libcrypto.so"/>
Note this bit:                                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For versions, see:

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.

13.4.6.2. Linux

Under Run Settings ‣ Run Environment, set LD_LIBRARY_PATH to point to the OpenSSL libraries we’ve built, e.g. LD_LIBRARY_PATH=/home/rudolf/dev/qt_local_build/openssl_linux_x86_64_build/openssl-1.1.1c/

You can also set this under Build Settings ‣ Build Environment, because the default behaviour is for the run environment to inherit the build environment.

13.4.6.4. 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.

13.4.7. Notes

13.4.7.1. 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

13.4.7.2. 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).

13.4.7.3. 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.

13.4.7.4. 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
    

Footnotes

1(1,2)

Prior to Qt 5.12.0, the compiler was “Android GCC (arm-4.9)”, and the debugger was “Android Debugger for Android GCC (arm-4.9)”.