source: trunk/doc/src/declarative/qmlviewer.qdoc@ 1036

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/*!

\page qmlviewer.html
\title QML Viewer
\ingroup qttools

The Declarative UI package includes \QQV, a tool for loading QML documents that 
makes it easy to quickly develop and debug QML applications. It invokes the QML 
runtime to load QML documents and also includes additional features useful for 
the development of QML-based applications.

The QML Viewer is a tool for testing and developing QML applications. It is 
\e not intended for use in a production environment and should not be used for the 
deployment of QML applications. In those cases, the QML runtime should be invoked
from a Qt application instead; see \l {Qt Declarative UI Runtime} for more
information.

The viewer is located at \c QTDIR/bin/qmlviewer. To load a \c .qml file
with the viewer, run the viewer and select the file to be opened, or provide the 
file path on the command line:

\code
    qmlviewer myqmlfile.qml
\endcode
    
On Mac OS X, the QML Viewer application is named "QMLViewer" instead. You
can launch the viewer by opening the QMLViewer application from the Finder, or 
from the command line:

\code
    QMLViewer.app/Contents/MacOS/QMLViewer myqmlfile.qml
\endcode

The QML Viewer has a number of configuration options involving features such as 
fullscreen display, module import path configurations, video recording of QML
animations, and OpenGL support.

To see the configuration options, run \c qmlviewer with the \c -help argument.


\section1 Adding module import paths

Additional module import paths can be provided using the \c -I flag.
For example, the \l{declarative/cppextensions/plugins}{QML plugins example} creates 
a C++ plugin identified as \c com.nokia.TimeExample. Since this has a namespaced
identifier, the viewer has to be run with the \c -I flag from the example's
base directory:

\code
qmlviewer -I . plugins.qml
\endcode

This adds the current directory to the import path so that the viewer will
find the plugin in the \c com/nokia/TimeExample directory.

Note by default, the current directory is included in the import search path,
but namespaced modules like \c com.nokia.TimeExample are not found unless
the path is explicitly added.


\section1 Loading translation files

When the QML Viewer loads a QML file, it installs a translation file from a 
"i18n" subdirectory relative to that initial file. This directory should contain 
translation files named "qml_<language>.qm", where <language> 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}.

The actual translation file that is loaded depends on the system locale. 
Additionally, the viewer will load any translation files specified on the command
line via the \c -translation option.

See the \l{declarative/i18n}{QML i18n example} for an example. Also, the
\l{scripting.html#internationalization}{Qt Internationalization} documentation
shows how JavaScript code in QML files can be made to use translatable strings.


\section1 Loading placeholder data with QML Viewer

Often, QML applications are prototyped with fake data that is later replaced
by real data sources from C++ plugins. QML Viewer assists in this aspect by
loading fake data into the application context: it looks for a directory named
"dummydata" in the same directory as the target QML file, and any \c .qml 
files in that directory are loaded as QML objects and bound to the root context
as properties named after the files.

For example, this QML document refers to a \c lottoNumbers property which does
not actually exist within the document:

\qml
import QtQuick 1.0

ListView {
    width: 200; height: 300
    model: lottoNumbers
    delegate: Text { text: number }
}        
\endqml

If within the document's directory, there is a "dummydata" directory which
contains a \c lottoNumbers.qml file like this:

\qml
import QtQuick 1.0

ListModel {
    ListElement { number: 23 }
    ListElement { number: 44 }
    ListElement { number: 78 }
}
\endqml

Then this model would be automatically loaded into the ListView in the previous document.

Child properties are included when loaded from dummy data. The following document
refers to a \c clock.time property:

\qml
import QtQuick 1.0    
Text { text: clock.time }
\endqml
    
The text value could be filled by a \c dummydata/clock.qml file with a \c time
property in the root context:

\qml
import QtQuick 1.0    
QtObject { property int time: 54321 }
\endqml

To replace this with real data, you can simply bind the real data object to
the root context in C++ using QDeclarativeContext::setContextProperty(). This
is detailed in \l {Using QML in C++ Applications}.

\section1 Using the \c runtime object

QML applications that are loaded with the QML Viewer have access to a special
\c runtime property on the root context. This property provides additional 
information about the application's runtime environment through the following properties:

\table
\row 

\o \c runtime.isActiveWindow

\o This property indicates whether the QML Viewer window is the current active
window on the system. It is useful for "pausing" an application, particularly
animations, when the QML Viewer loses focus or moves to the background.

For example, the following animation is only played when the QML Viewer is 
the active window:
    
\qml
Rectangle {
    width: 200; height: 200

    ColorAnimation on color {
        running: runtime.isActiveWindow
        loops: Animation.Infinite
        from: "green"; to: "blue"; duration: 2000
    }
}
\endqml

\row

\o \c runtime.orientation

\o This property indicates the current orientation of the QML Viewer. On the
N900 platform and most S60 5.0-based or newer Symbian devices, this property 
automatically updates to reflect the device's actual orientation; on other platforms, 
this indicates the orientation currently selected in the QML Viewer's 
\e {Settings -> Properties} menu. The \c orientation value can be one of the following:

\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

When the viewer's orientation changes, the appearance of the loaded QML document
does not change unless it has been set to respond to changes in 
\c runtime.orientation. For example, the following Rectangle changes its
aspect ratio depending on the orientation of the QML Viewer:

\qml
Rectangle {
    id: window
    width: 640; height: 480
            
    states: State {
        name: "landscape"
        PropertyChanges { target: window; width: 480; height: 640 }
    }
    state: (runtime.orientation == Orientation.Landscape 
            || runtime.orientation == Orientation.LandscapeInverted) ? 'landscape' : ''
}
\endqml

\endtable

*/