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Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: http://www.gnu.org/copyleft/fdl.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \page qtquick-porting-qt5.html \title QML Applications in Qt 5 \brief Lists the Qt 5.0 changes that affect the existing QML applications When porting QML-related code from Qt 4.8 to Qt 5, application developers should be aware that the QML infrastructure has undergone considerable changes in Qt 5. The sections below describe these changes and the impact they have on your existing code. This article describes the changes that affect your existing code. If you are interested in the summary of all new features in Qt 5 for QML application development, see \l{qtqml-releasenotes.html}{QtQml Release Notes} and \l{qtquick-releasenotes.html}{QtQuick Release Notes}. \section1 QtQuick Module The QtQuick module has been updated to version 2.0. All QML applications should update their import statements to use the new version: \qml import QtQuick 2.0 \endqml \section2 Property and Method Changes \list \li ListView's \c highlightMoveSpeed and \c highlightResizeSpeed properties have been renamed to \l{ListView::}{highlightMoveVelocity} and \l{ListView::}{highlightResizeVelocity}, respectively. \li TextInput and TextEdit's \c openSoftwareInputPanel() and \c closeSoftwareInputPanel() methods have been removed. Use the new Qt.inputMethod property and call Qt.inputMethod.show() Qt.inputMethod.hide() to show and hide the virtual keyboard. \endlist \section2 Type and API Changes \list \li XmlListModel has moved into its own module, QtQuick.XmlListModel. Any code that uses the XmlListModel and XmlRole types must import \e {QtQuick.XmlListModel} instead. \li The local storage API that enables SQL support has been moved from the \l {QML Global Object} into a \c QtQuick.LocalStorage singleton type. Any code that requires the local storage API must import \e {QtQuick.LocalStorage} instead. See the \l {QtQuick.LocalStorage 2}{QtQuick.LocalStorage} documentation for examples. \li The \c LayoutItem type has been removed from the \c QtQuick module as it was specific to the Graphics View framework backend used in QtQuick 1. \endlist \section2 Behavioral Changes QtQuick 2.0 includes a number of behavioral changes and you should thoroughly test your applications after porting. These changes will not necessarily lead to run-time errors, but may break certain assumptions in your code. Below are the prominent changes to be aware of when porting your applications. Item opacity and visibility: \list \li The input handling details of \l{Item::}{opacity} and \l{Item::}{visible} have changed. An opacity of zero no longer affects input handling, where previously it stopped mouse input. A visibility of false no longer affects keyboard input, but still stops mouse input. The new \l{Item::}{enabled} property stops mouse and keyboard input, but does not affect how or whether the item is rendered. A workaround for applying the old behavior in most cases is to bind enabled to \tt {(visible && opacity > 0.0)}. \li Previously, if an item was in a positioner (i.e. a \l Row, \l Column, \l Grid and \l Flow) and the item's \c opacity changed to 0, or its \c visible value became \c false, the positioner would remove the item from its layout and collapse the space for that item. In QtQuick 2.0, this now only happens when an item's \c visible is \c false; the item opacity no longer affects whether the item is laid out. (This is consistent with the existing behavior of ListView and GridView). \endlist Text: \list \li The TextEdit::textFormat property now defaults to \c PlainText instead of \c AutoText. \li When Text::textFormat is set to \c Text.AutoText format, the text object will automatically switch to \c Text.StyledText instead of \c Text.RichText. \endlist Other: \list \li Modifying the Image::sourceSize now fits the image to the size, maintaining aspect ratio. \li For ListView and GridView, the \c cacheBuffer property now has a non-zero default and delegates in the cache buffer are created asynchronously. Also, using a \c RightToLeft layout now also reverses the \c preferredHighlightBegin and \c preferredHighlightEnd. \li For \l Loader, the \c sourceChanged and \c sourceComponentChanged signals are now only emitted when their respective properties change value. (Previously \l Loader emitted both of these signals when either of the relevant properties had changed.) \endlist \section2 Changes to experimental Qt.labs modules \list \li The \c Qt.labs.particles module has been removed. It is replaced by the fully-fledged \l QtQuick.particles module which is an enormous improvement on its predecessor. \li The \c Qt.labs.shaders module has been removed as the \c ShaderEffectItem and \l ShaderEffectSource types from this module have been moved into the \l QtQuick module. Note the \c ShaderEffectItem type has been renamed to \l ShaderEffect. \endlist \section1 C++ code In Qt 5, all QML applications are rendered with an OpenGL scenegraph architecture rather than the Graphics View framework used in Qt 4. Due to the scale of this architectural change, the C++ API has been extensively restructured and the \c QtDeclarative module has been deprecated in favour of two new modules: \l QtQml, which implements the QML engine and language infrastructure, and \l QtQuick, which implements the visual canvas and scenegraph backend. All classes that were previously in the \c QtDeclarative module have been moved into the \l QtQml and \l QtQuick modules, and their class names have been changed to reflect their new module locations. The class name changes are as follows: \table \header \li QtQml \li QtQuick \row \li \list \li QDeclarativeComponent -> QQmlComponent \li QDeclarativeContext -> QQmlContext \li QDeclarativeEngine -> QQmlEngine \li QDeclarativeError -> QQmlError \li QDeclarativeExpression -> QQmlExpression \li QDeclarativeExtensionPlugin -> QQmlExtensionPlugin \li QDeclarativeInfo -> QQmlInfo \li QDeclarativeListReference -> QQmlListReference \li QDeclarativeNetworkAccessManagerFactory -> QQmlNetworkAccessManagerFactory \li QDeclarativeParserStatus -> QQmlParserStatus \li QDeclarativeProperty -> QQmlProperty \li QDeclarativePropertyMap -> QQmlPropertyMap \li QDeclarativePropertyValueSource -> QQmlPropertyValueSource \li QDeclarativeScriptString -> QQmlScriptString \endlist \li \list \li QDeclarativeItem -> QQuickItem \li QDeclarativeView -> QQuickView \li QDeclarativeImageProvider -> QQuickImageProvider \endlist \endtable To use the new \c QtQml* and \c QtQuick* classes in Qt 5, link against the approprate module from your qmake \c .pro file. For example the following will link against both the QtQml and QtQuick modules: \code QT += qml quick \endcode Required header files can then be included: \code #include #include \endcode (The \c QtDeclarative module is still available to developers as the \l QtQuick1 module, as discussed in \l{Using the QtDeclarative module in Qt 5}{below}. However, it should not be used for new applications.) \section3 QDeclarativeItem and QDeclarativeView When porting to QQuickItem, note that QDeclarativeItem inherited from QGraphicsItem; in contrast, QQuickItem inherits directly from QObject, and any QGraphicsItem-specific functionality is no longer available. In particular, QQuickItem does not have a \c paint() method for performing custom rendering through the QPainter API. Instead, in Qt 5, custom rendering should be performed through the new \c QSG* classes to take full advantage of the scene graph. See the \l {Qt Quick Scene Graph} documentation details on using these classes. Alternatively, the QQuickPaintedItem provides a \c paint() method and can be used as a convenient way to port QDeclarativeItem-based classes that use the QPainter API. Note this method is less performant than using the \c QSG* classes. When porting from QDeclarativeView to QQuickView, note that QDeclarativeItem inherited from QGraphicsView. In contrast, QQuickView inherits from QQuickWindow and uses the QWindow infrastructure introduced in Qt 5; any QGraphicsView-specific functionality is no longer available. \section3 qmlscene Utility The \c qmlviewer tool provided for prototyping and testing QML applications in Qt 4.x has been replaced with the \c qmlscene tool which integrates with the new scenegraph features in Qt 5. \section2 QML plugins All QML plugins should extend QQmlExtensionPlugin in Qt 5. Additionally, plugins should use the new Qt plugin infrastructure introduced in Qt 5. QML plugins no longer require the Q_EXPORT_PLUGIN2() macro. Instead, they should use the Q_PLUGIN_METADATA() macro within the plugin class declaration. See the updated \l {qtqml-modules-cppplugins.html}{Creating C++ Plugins For QML} documentation for an overview of creating QML plugins in Qt 5. \section2 QtDeclarative module in Qt 5 For the purposes of porting older applications, the \c QtDeclarative module is still available in Qt 5 but has been renamed to \c QtQuick1. Applications that required QtQuick 1 specific API (e.g. QDeclarativeView or QDeclarativeItem and the Graphics View integration) can use this module. Note that new applications should use the new \l QtQml and \l QtQuick modules instead. To use the \c QtQuick1 module, add “quick1” module to your qmake \c .pro file: \code QT += quick1 \endcode Required header files can be included from the QtQuick 1 module: \code #include #include \endcode */