UI files

If you switch between Qt Creator and Qt Design Studio or cooperate with designers on a project, you might encounter UI files (.ui.qml). They are intended to be edited in Qt Quick Designer or Qt Design Studio only.

By default, Qt Creator opens UI files in the Design mode. To open them with Qt Design Studio, select Open With > Qt Design Studio in the context menu for the file.

The following features are not supported in .ui.qml files:

• JavaScript blocks
• Other bindings than pure expressions
• Signal handlers
• States in other components than the root component
• Root components that are not derived from QQuickItem or Item
• Referencing the parent of the root component

The following components are not supported:

• Behavior
• Binding
• Canvas
• Shader Effect
• Timer
• Transform

Supported methods

Qt Creator supports most JavaScript functions that are supported by the QML engine, as well as a subset of Qt QML methods.

This section lists the functions that you can use in .ui.qml files.

JavaScript functions

As a rule of thumb, pure functions are supported. They only depend on and modify states of parameters that are within their scope, and therefore always return the same results when given the same parameters. This makes it possible to convert and reformat property bindings without breaking the .ui.qml files.

The following JavaScript functions are supported:

• charAt()
• charCodeAt()
• concat()
• endsWith()
• includes()
• indexOf()
• isFinite()
• isNaN()
• lastIndexOf()
• substring()
• toExponential()
• toFixed()
• toLocaleLowerCase()
• toLocaleString
• toLocaleUpperCase()
• toLowerCase()
• toPrecision()
• toString()
• toUpperCase()
• valueOf()

In addition, all functions of the Math and Date objects are supported.

For more information, see List of JavaScript Objects and Functions.

Qt QML methods

Qt Creator supports color methods, helper methods for creating objects of specific data types, and translation methods.

The following color methods are supported:

• Qt.darker()
• Qt.hsla()
• Qt.hsva()
• Qt.lighter()
• Qt.rgba()
• Qt.tint()

The following helper methods are supported:

• Qt.formatDate()
• Qt.formatDateTime()
• Qt.formatTime()
• Qt.matrix4x4()
• Qt.point()
• Qt.quaternion()
• Qt.rect()
• Qt.size()
• Qt.vector2d()
• Qt.vector3d()
• Qt.vector4d()

The following translation methods are supported:

• qsTr()
• qsTranslate()
• QT_TRANSLATE_NOOP()
• qsTrId()
• QT_TRID_NOOP()
• QT_TR_NOOP()

For more information about using the methods, see Qt QML Methods.

Using UI files

Edit the UI files in the Design mode. To use components in code, export them as properties:

Item {
    width: 640
    height: 480

    property alias button: button

    Button {
        anchors.centerIn: parent
        id: button
        text: qsTr("Press Me")
    }
}

The property alias exports the button to the code that uses the form. You can use the (Export) button in Navigator to export a component as a property:

In the UI file where the component is used, you can use the button property alias to implement signal handlers, for example. In the following code snippet, the UI file is called MainForm.ui.qml:

MainForm {
    anchors.fill: parent
    button.onClicked: messageDialog.show(qsTr("Button pressed"))
}

You can also assign properties or define behavior or transitions.

To move from the 2D or Navigator view directly to the implementation of a component in the .qml file, right-click the component and select Go to Implementation in the context menu.