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/****************************************************************************
**
** Copyright (C) 2019 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Creator documentation.
**
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** information use the contact form at https://www.qt.io/contact-us.
**
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** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
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** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
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****************************************************************************/
// **********************************************************************
// NOTE: the sections are not ordered by their logical order to avoid
// reshuffling the file each time the index order changes (i.e., often).
// Run the fixnavi.pl script to adjust the links to the index order.
// **********************************************************************
/*!
\contentspage index.html
\previouspage quick-export-to-qml.html
\page creator-qml-modules-with-plugins.html
\nextpage quick-converting-ui-projects.html
\title Using QML Modules with Plugins
QML modules may use plugins to expose components defined in C++ to QML
applications. \QC cannot load the plugins to determine the details of
the contained components, and therefore, the modules must provide extra type
information for code completion and the semantic checks to work correctly.
To create a QML module and make it appear in the \uicontrol Library in
the Design mode:
\list 1
\li Create custom QML controls and place all the \c .qml files in a
directory dedicated to your module.
\li Create a \c qmldir file for your module and place it in the module
directory. For more information, see
\l {Module Definition qmldir Files}.
\li Create a \c qmltypes file, preferably using \c qmlplugindump.
For more information see, \l {Generating qmltypes Files}.
\li Create a directory named \c designer in your module directory.
\li Create a \c .metainfo file for your module and place it in the
\c designer directory. Meta information is needed to display the
components in the \uicontrol {QML Types} tab in the \uicontrol
Library. Use a metainfo file delivered with Qt, such as
\c qtquickcontrols2.metainfo, as an example.
\li Import your module into a project using \c QML_IMPORT_PATH in the
.pro file: \c {QML_IMPORT_PATH += path/to/module}.
For more information, see \l {Importing QML Modules}.
\li Make sure that the QML emulation layer used in the Design mode is built with
the same Qt version as your QML modules. For more information, see
\l {Running QML Modules in Design Mode}. You can also try
skipping this step and take it later, if necessary.
\endlist
Your module should now appear in the \uicontrol Imports tab in the
\uicontrol Library in the Design mode. Your components should appear in the
\uicontrol {QML Types} tab if a valid \c .metainfo file is in place.
\section1 Registering QML Types
When you write a QML module or use QML from a C++ application, you typically
register new types with the qmlRegisterType() function or expose some
class instances with \l{QQmlContext::setContextProperty()}. The \QC C++
code model now scans for these calls and
tells the QML code model about them. This means that properties are
displayed during code completion and the JavaScript code checker does not
complain about unknown types. However, this works only when the source code
is available, and therefore, you must explicitly generate type information
for QML modules with plugins before distributing them.
Classes registered with \c qmlRegisterType() can be used as backend objects
in the Design mode. For more information, see \l {Adding Connections}.
\section1 Generating qmltypes Files
Ideally, QML modules have a \c{plugins.qmltypes} file in the same directory
as the \c qmldir file. The \c qmltypes file contains a description of the
types exported by the module's plugins and is loaded by \QC when the
module is imported.
For Qt 4.8 and later, one or more \c qmltypes files can be listed in the
\c qmldir file under the \c typeinfo header. These files will be read in
addition to \c{plugins.qmltypes}. For more information, see
\l{Writing a qmltypes File}.
You can create and edit \c qmltypes files manually, but you are recommended
to use the \c qmlplugindump tool shipped with Qt 4.8 and later to generate
them automatically.
Once you have obtained \c qmlplugindump for the Qt version the QML module's
plugins were compiled with, run the following command to load My.Module
version 1.0 from \c{/import/path/my/module} including all its plugins and
output a description of the plugins' types to
\c{/import/path/my/module/plugins.qmltypes}:
\code
qmlplugindump -nonrelocatable My.Module 1.0 /import/path > /import/path/my/module/plugins.qmltypes
\endcode
You can safely ignore the debug output.
For Qt 4.7.x, you can compile a version of the tool called \c qmldump from
the sources in \c{<QtCreator>/share/qtcreator/qml/qmldump} if the Qt version
contains private headers.
\section2 Dumping Plugins Automatically
If a module with plugins lacks the \c qmltypes file, \QC tries to generate
a temporary file itself by running the \c qmldump program in the background.
However, this automatic dumping is a fallback mechanism with many points of
failure and you cannot rely upon it.
\section1 Importing QML Modules
By default, \QC will look in the QML import path of Qt for QML modules.
If your applications adds additional import paths that \QC should use,
then you can specify those using \c{QML_IMPORT_PATH} in the \c{.pro} file of your
application.
If you use CMake, add the following command to the CMakeLists.txt file to
set the QML import path:
\code
{set(QML_IMPORT_PATH ${CMAKE_SOURCE_DIR}/qml ${CMAKE_BINARY_DIR}/imports CACHE string "" FORCE)}
\endcode
The import path affects all the targets built by the CMake project.
\section1 Running QML Modules in Design Mode
A QML emulation layer (also called QML Puppet) is used in the Design mode to
render and preview images and to collect data. To be able to render custom types
correctly from QML modules, the emulation layer must be built with the same
Qt version as the QML modules.
By default, a fallback emulation layer is provided by \QC and built with the same
Qt version as \QC. Therefore, your QML modules will mostly not work out of
the box.
To use an emulation layer that is built with the Qt
configured in the build and run kit for the project, select \uicontrol Tools >
\uicontrol Options > \uicontrol {Qt Quick} > \uicontrol {\QMLD} >
\uicontrol {Use QML emulation layer which is built by the selected Qt} radio button.
\QC builds the emulation layer when you select the Design mode.
A plugin should behave differently depending on whether it is run by the
emulation layer or an application. For example, animations should not be run
in the Design mode. You can use the value of the QML_PUPPET_MODE
environment variable to check whether the plugin is currently being run
by an application or edited in the Design mode.
If you want to use a different module in the Design mode than in your actual
application for example to mockup C++ items, then you can use \c{QML_DESIGNER_IMPORT_PATH}
in the \c{.pro} file (for qmake projects), or declare and set the property
qmlDesignerImportPaths in your product (for Qbs projects).
Modules in the import paths defined in \c{QML_DESIGNER_IMPORT_PATH} will be
used only in the Design mode.
For an example, see \l {Qt Quick Controls 2 - Contact List}.
*/
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