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QML is a runtime, as you can run plain QML files which pull in their required modules. To run apps with the QML runtime, you can either start the runtime from your own application (using a QDeclarativeView) or with the simple \QQV. The launcher can be installed in a production environment, assuming that it is not already present in the system. It is generally packaged alongside Qt. To deploy an application using the QML runtime, you have two options: \list \o Write your own Qt application including a QDeclarative view and deploy it the same as any other Qt application (not discussed further on this page), or \o Write a main QML file for your application, and run your application using the included \QQV. \endlist To run an application with the \QQV, pass the filename as an argument: \code qmlviewer myQmlFile.qml \endcode Deploying a QML application via the \QQV allows for QML only deployments, but can also include custom C++ modules just as easily. Below is an example of how you might structure a complex application deployed via the QML runtime, it is a listing of the files that would be included in the deployment package. \code MyApp.qml MyAppCore/qmldir MyAppCore/libMyAppCore.so MyAppCore/MyAppCore.dll MyAppCore/AnAppElement.qml MyAppCore/AnotherElement.qml MyAppCore/images/Logo.png OtherModule/qmldir OtherModule/OtherElement.qml \endcode Note that this example is for deploying the example to both windows and linux. You will still need to compile the C++ modules for each target platform, but you can deploy multiple versions of the modules across platforms with different naming conventions, as the appropriate module file is chosen based on platform naming conventions. The C++ modules must contain a QDeclarativeExtentionPlugin subclass. The application would be executed either with your own application, the command 'qmlviewer MyApp.qml' or by opening the file if your system has the \QQV registered as the handler for QML files. The MyApp.qml file would have access to all of the deployed types using the import statements such as the following: \code import "MyAppCore" import "OtherModule" 1.0 as Other \endcode \section1 Qt QML Viewer functionality The \QQV implements some additional functionality to help it supporting myriad applications. If you implement your own application, you may also wish to reimplement some or all of this functionality. However, much of this functionality is intended to aid the prototyping of QML applications and may not be necessary for a deployed application. \section2 Options When run with the \c -help option, \c qmlviewer shows available options. \section2 Translations When the launcher loads an initial QML file, it will install a translation file from a "i18n" subdirectory relative to that initial QML file. The actual translation file loaded will be according to the system locale and have the form "qml_.qm", where is a two-letter ISO 639 language, such as "qml_fr.qm", optionally followed by an underscore and an uppercase two-letter ISO 3166 country code, such as "qml_fr_FR.qm" or "qml_fr_CA.qm". Such files can be created using \l{Qt Linguist}. See the \l{scripting.html#internationalization}{Qt Internationalization} documentation for information about how to make the JavaScript in QML files use translatable strings. Additionally, the launcher will load translation files specified on the command line via the \c -translation option. \section2 Dummy Data The secondary use of the launcher is to allow QML files to be viewed with dummy data. This is useful when prototyping the UI, as the dummy data can be later replaced with actual data and bindings from a C++ plugin. To provide dummy data: create a directory called "dummydata" in the same directory as the target QML file and create files there with the "qml" extension. All such files will be loaded as QML objects and bound to the root context as a property with the name of the file (without ".qml"). To replace this with real data, you simply bind the real object to the root context in C++. For example, if the Qt application has a "clock.time" property that is a qreal from 0 to 86400 representing the number of seconds since midnight, dummy data for this could be provided by \c dummydata/clock.qml: \code QtObject { property real time: 12345 } \endcode Any QML can be used in the dummy data files. You could even animate the fictional data! \section2 Runtime Object All applications using the launcher will have access to the \c runtime property on the root context. This property contains several pieces of information about the runtime environment of the application. \section3 Screen Orientation A special piece of dummy data which is integrated into the launcher is a simple orientation property. The orientation can be set via the settings menu in the application, or by pressing Ctrl+T to rotate it. To use this from within your QML file, access \c runtime.orientation, which can be one of the following values: \list \o \c Orientation.Portrait \o \c Orientation.Landscape \o \c Orientation.PortraitInverted (Portrait orientation, upside-down) \o \c Orientation.LandscapeInverted (Landscape orientation, upside-down) \endlist These values can be bound to in your application. For example: \code Item { state: (runtime.orientation == Orientation.Landscape) ? 'landscape' : '' } \endcode This allows your application to respond to changes in the screen's orientation. The launcher will automatically update this on some platforms (currently the N900 only) to match the physical screen's orientation. On other plaforms orientation changes will only happen when explictly asked for. \section3 Window Active The \c runtime.isActiveWindow property tells whether the main window of the launcher is currently active or not. This is especially useful for embedded devices when you want to pause parts of your application, including animations, when your application loses focus or goes to the background. The example below, stops the animation when the application's window is deactivated and resumes on activation: \code Item { width: 300; height: 200 Rectangle { width: 100; height: 100 color: "green" SequentialAnimation on x { running: runtime.isActiveWindow loops: Animation.Infinite NumberAnimation {to: 200} NumberAnimation {to: 0} } } } \endcode */