Whew! Some things seem to take forever for me to figure out!
Here’s the scenario: we’re working on a Qt Quick (QML and C++) application at the lab to run on Microsoft Windows. We’d like to deploy the app to a bunch of study participants to use for a week or so. It’s obviously not practical for me to go around and set everybody up with Qt, Qt Mobility, and build our app. (Especially not this app; we’re using the Qt 4.8 prerelease at this point!). So we need to build a Windows installer that includes the Qt DLLs, our app and its QML, and the Qt Mobility plugins we’re using. We’re using Qt Mobility in our QML — so we need to include the Qt Mobility plugins for Qt Quick, not just the Qt Mobility libraries.
Packaging a Qt application for Windows is straightforward — just follow these instructions for packaging as a shared library. But what about the Qt Quick plugins for Qt Mobility we need?
Well, Qt Quick supports modules for that, as described here. In fact, if your application required QtWebKit’s Qt Quick plugin, you’d create a QtWebKit directory, stick a qmldir file with the line
plugin QtWebKit
copy qtwebkitplugin.dll into the directory you made and Bob’s your uncle!
We use QtMultimediaKit, so at first I created a QtMultimediaKit directory, created a qmldir file in that directory, and copied QtMultimediaKit1.dll from my Qt Mobility build output directory to the QtMultimediaKit directory I’d created.
No luck — in fact, the app just launches and shows nothing. (To add insult to injury, my app uses Qt’s support for Open GL, so not only did I not get the black screen characteristic of a QML error, but I got junk in the application window and no errors on the console.)
Turns out that QtMultimediaKit1.dll goes in the same directory as the application, and the declarative plugin file is somewhere else! If you look in the plugins directory, you’ll see a declarative directory, and the actual Qt Quick declarative plugin you’re looking for is in there! In my case, I needed to copy plugins/declarative/multimedia/release/declarative_multimedia.dll to a new directory QtMultimediaKit, create a single qmldir file that read
plugin declarative_multimedia
and put that adjacent to my application executable.
So, the resulting files and directories for me look something like:
imageformats/qgif4.dll
imageformats/qjpeg.dll
QtMultimediaKit/declarative_multimedia.dll
QtMultimediaKit/qmldir
msvcr90.dll
QtCore4.dll
QtDeclarative4.dll
QtGui4.dll
QtMultimedia4.dll
QtMultimediaKit1.dll
QtNetwork4.dll
QtOpenGL4.dll
QtScript4.dll
QtSql4,dll
QtXml4.dll
QtXmlPatterns4.dll
myapplication.exe
Now off to learn how to make a Windows installer. I think I’ll try Inno Setup.