Unable to launch Qt Assistant

Mark Brethen mark.brethen at gmail.com
Mon Jul 14 20:28:45 PDT 2014

On Jul 14, 2014, at 10:09 PM, Ian Wadham <iandw.au at gmail.com> wrote:

> On 15/07/2014, at 10:56 AM, Mark Brethen wrote:
>> On Jul 14, 2014, at 6:22 PM, Mark Brethen <mark.brethen at gmail.com> wrote:
>>> I'm testing the FreeCAD build and discovered that the help menu returns the error message: "Unable to launch Qt Assistant (/opt/local/bin/Assistant.app/Contents/MacOS/Assistant)".  Launching Qt Assistant is done in the function startAssistant() which is found in src/Gui/Assistant.cpp. The following lines get the name of the executable and the doc path:
>>> #ifdef Q_OS_WIN
>>>      QString app;
>>>      app = QDir::toNativeSeparators(QString::fromUtf8
>>>          (App::GetApplication().GetHomePath()) + QLatin1String("bin/"));
>>> #else
> As a quick and dirty fix, you could include here:
>       #ifdef Q_OS_MAC
>             QString app = "/Applications/MacPorts/Qt4/";
>       #else
>>>      QString app = QLibraryInfo::location(QLibraryInfo::BinariesPath) + QDir::separator();
>       #endif
>>> #endif 
>>> #if !defined(Q_OS_MAC)
>>>      app += QLatin1String("assistant");
>>> #else
>>>      app += QLatin1String("Assistant.app/Contents/MacOS/Assistant");
>>> #endif
>>>      QString exe = QString::fromUtf8(App::GetApplication().getExecutableName());
>>>      QString doc = QString::fromUtf8(App::Application::getHelpDir().c_str());
>>>      QString qhc = doc + exe.toLower() + QLatin1String(".qhc");
>>> I'm not that familiar with c++ but I believe 'QLibraryInfo::location(QLibraryInfo::BinariesPath) + QDir::separator()' is setting the variable 'app' to /opt/local/bin. This line needs to be patched so that it finds /Applications/Macports/Qt4. How is a string used as a file path In c++?
>> In other words, how is the macports variable included in the patch? 
>> QString app = ${applications_dir} + QLatin1String("Qt/");
> Note the extra #endif.
> I don't know the "official" way to obtain the applications bundle path from Qt4-Mac.
> Using the literal path as above will get you the "standard" MacPorts bundle path
> for Qt4 apps, if and only if you have used MacPorts to install the apps and used
> the default MacPorts locations.  So it will get you off the ground, but it is in no way
> "general" to any installation of FreeCAD on any Apple OS X host machine.
> Cheers, Ian W.

Since this bit of code pertains only to FreeCAD built with macports, this post-patch works for me:

post-patch {
    reinplace "s|QLibraryInfo::location.*|QLatin1String\(\"${applications_dir}/Qt4/\"\);|" \

I also discovered that macports' Qt4-mac port does not build with sqlite support and added the plugin as a run dependency:

depends_run             port:qt4-mac-sqlite3-plugin


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