Import Statements Imports Statement

Syntax of an Import Statement

Syntax for import statements

An import statement allows clients to tell the engine which modules, JavaScript resources and component directories is US Ed within a QML document. The types which is used within a document depends on which modules, resources and directories is imported by the docu ment.

The import statement allows the customer to tell the engine which modules, JavaScript resources, and component catalogs are available in the QML document. What types can be used within a document depends on the modules, resources, and directories that are imported into the document.

Import Types

Import type

There is three different types of imports. Each import type have a slightly different syntax, and different semantics apply to different import types.

There are 3 different types of imports. Each import type has a slightly different syntactic difference, and the semantics apply to different import types.

Module (Namespace) Imports

Import of modules

The most common type of import is a module import. Clients can import QML modules which register QML object types and JavaScript resources into a given namespace.

The most common import is module import. Customers can import modules and JavaScript resources registered with the object type into a given namespace.

The generic form of a module import is as follows:

The general form of module import is as follows:

Import <ModuleIdentifier> <Version.Number> [as <qualifier>]

The <ModuleIdentifier> is a identifier specified in dotted URI notation, which uniquely identifies the type Namespa Ce provided by the module.

The <Version.Number> is a Version of the form majorversion.minorversion which specifies which definitions of various Object types and JavaScript resources would be made available due to the import.

The <Qualifier> is a optional local namespace identifier into which the object types and JavaScript resources provi Ded by the module would be installed, if given. If omitted, the object types and JavaScript resources provided by the module would be installed into the global namespace.

<ModuleIdentifier> is the identifier specified by the dot URI notation, which is the unique identification of the namespace type provided by the module.

<Version.Number> is a large version. The version number of the minor version format. Specifies which version of each object type and JavaScript resource which definition will be supplied to the import.

<Qualifier> is an optional local namespace, and if given, it is installed as the object type provided by the module and the identification (namespace) of the JavaScript resource. If omitted, the object type provided by the module and the JavaScript resource will be installed into the global namespace.

An example of a unqualified module import is as follows:

The following is an example of an unqualified module import:

Import QtQuick 2.0

This import allows the "all of the" of the types provided by the QtQuick module without needing to specify a qualifier. For example, the client code to create a rectangle is as follows:

This allows the import to use all the types provided by the QtQuick module, without specifying a qualification (the namespace). For example, the customer code can be created rectangle as follows:

Import QtQuick 2.0Rectangle {    width:200    height:100    color: "Red"}

An example of a qualified module import is as follows:

The following is a qualified module import:

Import QtQuick 2.0 as Quick

This import allows multiple modules which provide conflicting type names to is imported at the same time, however since EA CH usage of a type provided by a module which is imported into a qualified namespace must is preceded by the qualifier, T He conflict is able to being resolved unambiguously by the QML engine.

This allows the import of multiple supplied types with name collisions, since each type is provided by the module that is imported to qualify the namespace, so the qualifier must precede the use (which can be understood as a namespace), and the conflict can be resolved explicitly by the QML engine.

An example of the client code which creates a rectangle after using a qualified module import is as follows:

The following is an example of creating a rectangle with a customer code imported using a qualified module:

Import QtQuick 2.0 as Quickquick.rectangle {    width:200    height:100    color: "Red"}

For more information about qualified imports, see the upcoming sections on importing into A qualified Local Namespace.

For more information about restricted imports, see the next section <importing into A qualified local namespace> import into a qualified native namespace.

Note If a QML document does not import a module which provides a particular QML object type, but attempts Object type anyway, an error would occur.

Note that if the QML document does not import a module that provides a specific QML object type, but attempting to use that object type will result in an error.

For example, the following QML document does not import QtQuick and thus attempting to use the Rectangle type would fail:

For example, the following QML document does not import QtQuick and attempts to use the Rectangle type will fail:

Rectangle {    width:200    height:100    color: "Red"}

In this case, the engine would emit an error and refuse to load the file.

In this case, the engine will emit an error and refuse to load the file.

Non-module Namespace Imports

No module namespace Import

Types can also be registered to namespaces directly via the various registration functions in C + + (such as Qmlregisterty PE ()). The types which has been registered into a namespace on this-to-be imported by importing the namespace, as if the NA Mespace was a module identifier.

Types can also be registered directly in C + + through a variety of registration functions to the namespace (for example, the Qmlregistertype () function). The type that is registered into the namespace can be imported through the import namespace, as if the namespace were a module identity.

Common in client applications which define their own QML object types in C + + and register them with the QML t ype system manually.

This is most commonly used in client programs, defining their own QML object types in C + + and registering them manually on the QML type system.

Importing into a qualified Local Namespace

Import a qualified local namespace

The import statement may optionally use the AS keyword to specify that the types should is imported into a particular docu Ment-local namespace. If a namespace is specified and then any references to the types made available by the import must being prefixed by the local n Amespace qualifier.

The import statement can optionally use the keyword to specify that the type should be imported into a specific local document namespace. If you specify a namespace, any imported type that you want to reference must be qualified with the local namespace prefix.

Below, the QtQuick module is imported into the namespace "Coreitems". Now, any references to types from the QtQuick module must is prefixed with the Coreitems name:

as follows, the QtQuick module is imported into the namespace "Coreitems". Any type that references the QtQuick module must now use the Coreitems prefix:

Import QtQuick 2.0 as Coreitemscoreitems.rectangle {    width:100; height:100    coreitems.text {Text: "Hello, world! "}    //wrong! No namespace prefix-the text type won ' t be found    text {text: "Hello, world!"}}

A namespace acts as an identifier for a module within the scope of the file. The namespace does not become a attribute of the root object that can is referred to externally as can do with Prope Rties, signals and methods.

namespace as the identity of the module within the scope of the file. Namespaces are not manipulated like properties, signals, and methods, and do not become properties that can be referenced to external root objects.

The namespaced import is useful if there be a requirement to use the QML types that has the same name but be located in Different modules. In this case the the both modules can be imported into different namespaces to ensure the code was referring to the correct type :

Namespace portals are useful if you need to use 2 QML types that have the same name but are located in different modules. In this case 2 modules can be imported into different namespaces to ensure that the code references the correct type:

Import QtQuick 2.0 as Coreitemsimport "..  /textwidgets "as Mymodulecoreitems.rectangle {    width:100; height:100    mymodule.text {Text:" Hello from my Custom Text item! "}    Coreitems.text {Text: "Hello from Qt quick!"}}

Note that multiple modules can is imported into the same namespace in the same a-part multiple modules can be imported I Nto the global namespace. For example:

Note that multiple modules can be imported into the same namespace, and the same multi-module can be imported into the global namespace. For example:

Import QtQuick 2.0 as Projectimport Qtmultimedia 5.0 as Projectproject.rectangle {    width:100; height:50    Project. Audio {        Source: "Music.wav"        Autoplay:true    }}

Directory Imports

Import of Catalogs

A directory which contains QML documents may also is imported directly in a QML document. This provides a simple-to-QML types to be segmented into reusable groupings:directories on the filesystem.

Directories containing QML documents can also be imported directly into the QML document. This provides an easy way to split the QML type into reusable groups: directories on the file system.

The generic form of a directory import is as follows:

The format of the catalog import is usually as follows:

Import "<DirectoryPath>" [as <qualifier>]

Note:import paths is network transparent:applications can Import documents from remote paths just as simply as document s from local paths. See the general URL resolution rules for Network Transparency in QML documents. If The directory is remote, it must contain a directory import listing Qmldir file as the QML engine cannot determine the Contents of a remote directory if that qmldir file does not exist.

Note: The import path is network-transparent: An application can import documents from a remote path as simple as importing from a local path. View the Web-transparent URL resolution rules for a generic QML document. If the directory is remote, it must contain a (directory import manifest) Qmldir file If the Qmldir file does not exist QML the engine cannot determine the contents of the remote directory.

Similar semantics for the <Qualifier> apply to directory imports as for module imports; For more information on the topic, please see the previous sections about importing into a qualified Local Namespace.

<Qualifier> Application to catalog Import and module import have the same semantics; For more information, see the previous section <importing into a qualified Local namespace>.

For more information on directory imports, please see the in-depth documentation about directory imports.

For more information about catalog import, see more in-depth documentation <directory imports>.

JavaScript Resource Imports

Import of JavaScript resources

JavaScript resources is imported directly in a QML document. Every JavaScript resource must has an identifier by which it is accessed.

JavaScript resources can be imported directly into the QML document. Each JavaScript resource must have an identity for its visitors.

The generic form of a JavaScript resource import is as follows:

The import format for JavaScript resources is usually as follows:

Import "<JavaScriptFile>" as <Identifier>

Note that the <Identifier> must is unique within a QML document, unlike the local namespace qualifier which can be a Pplied to module imports.

Note <Identifier> must be unique within the QML document, unlike local namespace qualifiers that can be applied to module portals.

JavaScript Resources from Modules

JavaScript resources from the module

Javascript files can be provided by modules, by adding identifier definitions to the Qmldir file which specifies the Modul E.

The module can provide JavaScript files, by adding an identity description to the Qmldir file, which is used to specify the module's Qmldir file.

For example, if the projects. Myqmlproject.myfunctions module is specified with the following Qmldir file, and installed into the QML import path:

For example, if projects. The Myqmlproject.myfunctions module is specified by the following Qmldir file and is installed in the QML portal path:

Module projects. Myqmlproject.myfunctionssystemfunctions 1.0 systemfunctions.jsuserfunctions 1.0 userfunctions.js

A client application is able to import the JavaScript resources declared in the module by importing the module and using T He identifier associated with a declared resource:

The client application can import the module to import the declared JavaScript resources within the module, and use identities to correlate to the corresponding declared resources.

Import QtQuick 2.0import projects. Myqmlproject.myfunctions 1.0Item {    component.oncompleted: {systemfunctions.cleanup ();}}

If the module is imported into a document-local namespace, the JavaScript resource identifiers must is prefixed with the Namespace qualifier in order to be used:

If the module is imported into the namespace of the document local, the JavaScript resource identity must be prefixed with the namespace qualifier before it can be used:

Import QtQuick 2.0import projects. Myqmlproject.myfunctions 1.0 as Myfuncsimport org.example.Functions 1.0 as Theirfuncsitem {    component.oncompleted: {        MyFuncs.SystemFunctions.cleanUp ();        TheirFuncs.SystemFunctions.shutdown ();    }}

Further information

Supplemental information

For more information about JavaScript resources, please see the documentation about defining JavaScript resources in QML, And for more information on how to import the JavaScript resources, and how the imports can be used from within JavaScript Reso Urces, please see the in-depth documentation for importing JavaScript resources in QML.

For more information about JavaScript resources, see QML documentation <defining JavaScript resources in qml> defining JavaScript resource in QML For more information about importing JavaScript resources, how to import inside JavaScript resources, see more in-depth documentation <importing JavaScript resource in qml> Import JavaScript resources in QML.

QML Import Path

QML Import Path

When an identified module was imported, the QML engine searches the import path for a matching module.

When the identified module is imported, the QML engine looks for the matching module's import path.

This import is path, as returned by Qqmlengine::importpathlist (), defines the default locations to being searched by the engine. By default, this list contains:

This import path, as the return value of Qqmlengine::importpathlist (), defines the engine search by default. By default, the list consists of:

1 The directory of the current file

2 the location specified by Qlibraryinfo::qml2importspath

3 Paths specified by the QML2_IMPORT_PATH environment variable

Additional import paths can be added through Qqmlengine::addimportpath () or the QML2_IMPORT_PATH environment variable. When running the Qmlscene tool, you can also use the-i option to add an import path.

Additional import paths can be added via Qqmlengine::addimportpath () or environment variable Qml2_import_path. When you run the Qmlscene tool, you can use the-I option to add an import path.

Debugging

The QML_IMPORT_TRACE environment variable can be useful for debugging when there is problems with finding and loading mod Ules. See Debugging module imports for more information.

environment variable qml_import_trace is useful for debugging when there is a problem locating and loading the module. For more detailed information, see the import of the Debug module.

Import Statements Imports Statement