Module Definition qmldir Files

There are two distinct types of qmldir files:

• QML document directory listing files
• QML module definition files

This documentation covers only the second form of qmldir file. For more information about the first form of qmldir file, please see the documentation about directory listing qmldir files.

Contents of a Module Definition qmldir File

A qmldir file is a plain-text file that contains the following commands:

  module <ModuleIdentifier>

  module ExampleModule

  [singleton] <TypeName> <InitialVersion> <File>

  //Style.qml with custom singleton type definition
  pragma Singleton
  import QtQuick 2.0

  QtObject {
      property int textSize: 20
      property color textColor: "green"
  }

  // qmldir declaring the singleton type
  module CustomStyles
  singleton Style 1.0 Style.qml

  // singleton type in use
  import QtQuick 2.0
  import CustomStyles 1.0

  Text {
      font.pixelSize: Style.textSize
      color: Style.textColor
      text: "Hello World"
  }

  internal <TypeName> <File>

  internal MyPrivateType MyPrivateType.qml

  <ResourceIdentifier> <InitialVersion> <File>

  MyScript 1.0 MyScript.js

  plugin <Name> [<Path>]

  plugin MyPluginLibrary

  classname <C++ plugin class>

  typeinfo <File>

  typeinfo mymodule.qmltypes

  depends <ModuleIdentifier> <InitialVersion>

  depends MyOtherModule 1.0

  # <Comment>

  # this is a comment

  designersupported

Each command in a qmldir file must be on a separate line.

Versioning Semantics

Types which are exported for a particular version are still made available if a later version is imported. If a module provides a MyButton type in version 1.0 and a MyWindow type in version 1.1, clients which import version 1.1 of the module will be able to use the MyButton type and the MyWindow type. However, the reverse is not true: a type exported for a particular version cannot be used if an earlier version is imported. If the client had imported version 1.0 of the module, they can use the MyButton type but not the MyWindow type.

A version cannot be imported if no types have been explicitly exported for that version. If a module provides a MyButton type in version 1.0 and a MyWindow type in version 1.1, you cannot import version 1.2 or version 2.0 of that module.

A type can be defined by different files in different versions. In this case, the most closely matching version will be used when imported by clients. For example, if a module had specified the following types via its qmldir file:

  module ExampleModule
  MyButton 1.0 MyButton.qml
  MyButton 1.1 MyButton11.qml
  MyButton 1.3 MyButton13.qml
  MyButton 2.0 MyButton20.qml
  MyRectangle 1.2 MyRectangle12.qml

a client who imports version 1.2 of ExampleModule will get the MyButton type definition provided by MyButton11.qml as it is the most closely matching (i.e., latest while not being greater than the import) version of the type, and the MyRectangle type definition provided by MyRectangle12.qml.

The versioning system ensures that a given QML file will work regardless of the version of installed software, since a versioned import only imports types for that version, leaving other identifiers available, even if the actual installed version might otherwise provide those identifiers.

Example of a qmldir File

One example of a qmldir file follows:

  module ExampleModule
  CustomButton 1.0 CustomButton.qml
  CustomButton 2.0 CustomButton20.qml
  CustomButton 2.1 CustomButton21.qml
  plugin examplemodule
  MathFunctions 2.0 mathfuncs.js

The above qmldir file defines a module called "ExampleModule". It defines the CustomButton QML object type in versions 1.1, 2.0 and 2.1 of the module, with different implementations in each version. It specifies a plugin which must be loaded by the engine when the module is imported by clients, and that plugin may register various C++-defined types with the QML type system. On Unix-like systems the QML engine will attempt to load libexamplemodule.so as a QQmlExtensionPlugin, and on Windows it will attempt to load examplemodule.dll as a QQmlExtensionPlugin. Finally, the qmldir file specifies a JavaScript resource which is only available if version 2.0 or greater of the module is imported, accessible via the MathFunctions identifier.

If the module is installed into the QML import path, clients could import and use the module in the following manner:

  import QtQuick 2.0
  import ExampleModule 2.1

  Rectangle {
      width: 400
      height: 400
      color: "lightsteelblue"

      CustomButton {
          color: "gray"
          text: "Click Me!"
          onClicked: MathFunctions.generateRandom() > 10 ? color = "red" : color = "gray";
      }
  }

The CustomButton type used above would come from the definition specified in the CustomButton21.qml file, and the JavaScript resource identified by the MathFunctions identifier would be defined in the mathfuncs.js file.

Writing a qmltypes File

QML modules may refer to one or more type information files in their qmldir file. These usually have the .qmltypes extension and are read by external tools to gain information about types defined in plugins.

As such qmltypes files have no effect on the functionality of a QML module. Their only use is to allow tools such as Qt Creator to provide code completion, error checking and other functionality to users of your module.

Any module that uses plugins should also ship a type description file.

The best way to create a qmltypes file for your module is to generate it using the qmlplugindump tool that is provided with Qt.

Example: If your module is in /tmp/imports/My/Module, you could run

  qmlplugindump My.Module 1.0 /tmp/imports > /tmp/imports/My/Module/mymodule.qmltypes

to generate type information for your module. Afterwards, add the line

  typeinfo mymodule.qmltypes

to /tmp/imports/My/Module/qmldir to register it.

While the qmldump tool covers most cases, it does not work if:

• The plugin uses a QQmlCustomParser. The component that uses the custom parser will not get its members documented.
• The plugin can not be loaded. In particular if you cross-compiled the plugin for a different architecture, qmldump will not be able to load it.

In case you have to create a qmltypes file manually or need to adjust an existing one, this is the file format:

  import QtQuick.tooling 1.1

  // There always is a single Module object that contains all
  // Component objects.
  Module {
      // A Component object directly corresponds to a type exported
      // in a plugin with a call to qmlRegisterType.
      Component {

          // The name is a unique identifier used to refer to this type.
          // It is recommended you simply use the C++ type name.
          name: "QQuickAbstractAnimation"

          // The name of the prototype Component.
          prototype: "QObject"

          // The name of the default property.
          defaultProperty: "animations"

          // The name of the type containing attached properties
          // and methods.
          attachedType: "QQuickAnimationAttached"

          // The list of exports determines how a type can be imported.
          // Each string has the format "URI/Name version" and matches the
          // arguments to qmlRegisterType. Usually types are only exported
          // once, if at all.
          // If the "URI/" part of the string is missing that means the
          // type should be put into the package defined by the URI the
          // module was imported with.
          // For example if this module was imported with 'import Foo 4.8'
          // the Animation object would be found in the package Foo and
          // QtQuick.
          exports: [
              "Animation 4.7",
              "QtQuick/Animation 1.0"
          ]

          // The meta object revisions for the exports specified in 'exports'.
          // Describes with revisioned properties will be visible in an export.
          // The list must have exactly the same length as the 'exports' list.
          // For example the 'animations' propery described below will only be
          // available through the QtQuick/Animation 1.0 export.
          exportMetaObjectRevisions: [0, 1]

          Property {
              name: "animations";
              type: "QQuickAbstractAnimation"
              // defaults to false, whether this property is read only
              isReadonly: true
              // defaults to false, whether the type of this property was a pointer in C++
              isPointer: true
              // defaults to false: whether the type actually is a QQmlListProperty<type>
              isList: true
              // defaults to 0: the meta object revision that introduced this property
              revision: 1
          }
          Property { name: "loops"; type: "int" }
          Property { name: "name"; type: "string" }
          Property { name: "loopsEnum"; type: "Loops" }

          Enum {
              name: "Loops"
              values: {
                  "Infinite": -2,
                  "OnceOnly": 1
              }
          }

          // Signal and Method work the same way. The inner Parameter
          // declarations also support the isReadonly, isPointer and isList
          // attributes which mean the same as for Property
          Method { name: "restart" }
          Signal { name: "started"; revision: 2 }
          Signal {
              name: "runningChanged"
              Parameter { type: "bool" }
              Parameter { name: "foo"; type: "bool" }
          }
      }
  }