QtQml.Qt

Provides a global object with useful enums and functions from Qt. More...

Properties

• application : object
• inputMethod : object
• platform : object

Methods

• string atob(data)
• binding(function)
• string btoa(data)
• color colorEqual(color lhs, string rhs)
• object createComponent(url, mode, parent)
• object createQmlObject(string qml, object parent, string filepath)
• color darker(color baseColor, real factor)
• font(object fontSpecifier)
• list<string> fontFamilies()
• string formatDate(datetime date, variant format)
• string formatDateTime(datetime dateTime, variant format)
• string formatTime(datetime time, variant format)
• color hsla(real hue, real saturation, real lightness, real alpha)
• object include(string url, jsobject callback)
• bool isQtObject(object)
• color lighter(color baseColor, real factor)
• locale(name)
• string md5(data)
• matrix4x4(real m11, real m12, real m13, real m14, real m21, real m22, real m23, real m24, real m31, real m32, real m33, real m34, real m41, real m42, real m43, real m44)
• bool openUrlExternally(url target)
• point point(int x, int y)
• string qsTr(string sourceText, string disambiguation, int n)
• string qsTrId(string id, int n)
• string qsTrIdNoOp(string id)
• string qsTrNoOp(string sourceText, string disambiguation)
• string qsTranslate(string context, string sourceText, string disambiguation, int n)
• string qsTranslateNoOp(string context, string sourceText, string disambiguation)
• quaternion(real scalar, real x, real y, real z)
• quit()
• rect rect(int x, int y, int width, int height)
• url resolvedUrl(url url)
• color rgba(real red, real green, real blue, real alpha)
• size(int width, int height)
• color tint(color baseColor, color tintColor)
• vector2d(real x, real y)
• vector3d(real x, real y, real z)
• vector4d(real x, real y, real z, real w)

Detailed Description

The Qt object is a global object with utility functions, properties and enums.

It is not instantiable; to use it, call the members of the global Qt object directly. For example:

import QtQuick 2.0
Text {
color: Qt.rgba(1, 0, 0, 1)
text: Qt.md5("hello, world")
}

Enums

The Qt object contains the enums available in the Qt Namespace. For example, you can access the Qt::LeftButton and Qt::RightButton enumeration values as Qt.LeftButton and Qt.RightButton.

Types

The Qt object also contains helper functions for creating objects of specific data types. This is primarily useful when setting the properties of an item when the property has one of the following types:

• rect - use Qt.rect()
• point - use Qt.point()
• size - use Qt.size()

If the QtQuick module has been imported, the following helper functions for creating objects of specific data types are also available for clients to use:

• color - use Qt.rgba(), Qt.hsla(), Qt.darker(), Qt.lighter() or Qt.tint()
• font - use Qt.font()
• vector2d - use Qt.vector2d()
• vector3d - use Qt.vector3d()
• vector4d - use Qt.vector4d()
• quaternion - use Qt.quaternion()
• matrix4x4 - use Qt.matrix4x4()

There are also string based constructors for these types. See QML Basic Types for more information.

Date/Time Formatters

The Qt object contains several functions for formatting QDateTime, QDate and QTime values.

• string Qt.formatDateTime(datetime date, variant format)
• string Qt.formatDate(datetime date, variant format)
• string Qt.formatTime(datetime date, variant format)

The format specification is described at Qt.formatDateTime.

Dynamic Object Creation

The following functions on the global object allow you to dynamically create QML items from files or strings. See Dynamic QML Object Creation from JavaScript for an overview of their use.

• object Qt.createComponent(url)
• object Qt.createQmlObject(string qml, object parent, string filepath)

Other Functions

The following functions are also on the Qt object.

• Qt.quit()
• Qt.md5(string)
• string Qt.btoa(string)
• string Qt.atob(string)
• object Qt.binding(function)
• object Qt.locale()
• string Qt.resolvedUrl(string)
• Qt.openUrlExternally(string)
• list<string> Qt.fontFamilies()

Property Documentation

The application object provides access to global application state properties shared by many QML components.

Its properties are:

The object also has one signal, aboutToQuit(), which is the same as QCoreApplication::aboutToQuit().

The following example uses the application object to indicate whether the application is currently active:

import QtQuick 2.0
Rectangle {
width: 300; height: 55
color: Qt.application.active ? "white" : "lightgray"
Text {
text: "Application " + (Qt.application.active ? "active" : "inactive")
opacity: Qt.application.active ? 1.0 : 0.5
anchors.centerIn: parent
}
}

Note that when using QML without a QGuiApplication, the following properties will be undefined:

• application.active
• application.state
• application.layoutDirection

This QML property was introduced in Qt 5.1.

The inputMethod object allows access to application's QInputMethod object and all its properties and slots. See the QInputMethod documentation for further details.

This QML property was introduced in Qt 5.0.

The platform object provides info about the underlying platform.

Its properties are:

This QML property was introduced in Qt 4.8.

Method Documentation

ASCII to binary - this function returns a base64 decoding of data.

Returns a JavaScript object representing a property binding.

There are two main use-cases for the function: firstly, to apply a property binding imperatively from JavaScript code:

Item {
property bool someCondition: true
property int edgePosition
Component.onCompleted: {
if (someCondition == true) {
// bind to the result of the binding expression passed to Qt.binding()
edgePosition = Qt.binding(function() { return x + width })
}
}
}

and secondly, to apply a property binding when initializing property values of dynamically constructed objects (via Component.createObject() or Loader.setSource()).

For example, assuming the existence of a DynamicText component:

import QtQuick 2.0
Text {
id: textElement
width: 200
height: 200
text: "Default text"
property string dynamicText: "Dynamic text"
onTextChanged: console.log(text)
}

the output from:

Item {
id: root
property string dynamicText: "Root text"
Component.onCompleted: {
var c = Qt.createComponent("DynamicText.qml")
var obj1 = c.createObject(root, { 'text': Qt.binding(function() { return dynamicText + ' extra text' }) })
root.dynamicText = "Modified root text"
var obj2 = c.createObject(root, { 'text': Qt.binding(function() { return this.dynamicText + ' extra text' }) })
obj2.dynamicText = "Modified text element text"
}
}

and from:

Item {
id: root
property string dynamicText: "Root text"
Loader {
id: loaderOne
onLoaded: root.dynamicText = "Modified root text"
}
Loader {
id: loaderTwo
onLoaded: item.dynamicText = "Modified dynamic text"
}
Component.onCompleted: {
loaderOne.setSource("DynamicText.qml", { 'text': Qt.binding(function() { return dynamicText + ' extra text' }) })
loaderTwo.setSource("DynamicText.qml", { 'text': Qt.binding(function() { return this.dynamicText + ' extra text' }) })
}
}

should both be:

Root text extra text
Modified root text extra text
Dynamic text extra text
Modified dynamic text extra text

This function cannot be used in property binding declarations (see the documentation on binding declarations and binding assignments) except when the result is stored in an array bound to a var property.

Item {
width: 50
property var storedBindings: [ Qt.binding(function() { return x + width }) ] // stored
property int a: Qt.binding(function() { return x + width }) // error!
property int b
Component.onCompleted: {
b = storedBindings[0] // causes binding assignment
}
}

Note: In Qt Quick 1, all function assignments were treated as binding assignments. The Qt.binding() function is new to Qt Quick 2.

This QML method was introduced in Qt 5.0.

Binary to ASCII - this function returns a base64 encoding of data.

Returns true if both lhs and rhs yield equal color values. Both arguments may be either color values or string values. If a string value is supplied it must be convertible to a color, as described for the color basic type.

Returns a Component object created using the QML file at the specified url, or null if an empty string was given.

The returned component's Component::status property indicates whether the component was successfully created. If the status is Component.Error, see Component::errorString() for an error description.

If the optional mode parameter is set to Component.Asynchronous, the component will be loaded in a background thread. The Component::status property will be Component.Loading while it is loading. The status will change to Component.Ready if the component loads successfully, or Component.Error if loading fails.

If the optional parent parameter is given, it should refer to the object that will become the parent for the created Component object.

Call Component.createObject() on the returned component to create an object instance of the component.

For example:

import QtQuick 2.0
Item {
id: container
width: 300; height: 300
function loadButton() {
var component = Qt.createComponent("Button.qml");
if (component.status == Component.Ready) {
var button = component.createObject(container);
button.color = "red";
}
}
Component.onCompleted: loadButton()
}

See Dynamic QML Object Creation from JavaScript for more information on using this function.

To create a QML object from an arbitrary string of QML (instead of a file), use Qt.createQmlObject().

Returns a new object created from the given string of QML which will have the specified parent, or null if there was an error in creating the object.

If filepath is specified, it will be used for error reporting for the created object.

Example (where parentItem is the id of an existing QML item):

var newObject = Qt.createQmlObject('import QtQuick 2.0; Rectangle {color: "red"; width: 20; height: 20}',
parentItem, "dynamicSnippet1");

In the case of an error, a Qt Script Error object is thrown. This object has an additional property, qmlErrors, which is an array of the errors encountered. Each object in this array has the members lineNumber, columnNumber, fileName and message. For example, if the above snippet had misspelled color as 'colro' then the array would contain an object like the following: { "lineNumber" : 1, "columnNumber" : 32, "fileName" : "dynamicSnippet1", "message" : "Cannot assign to non-existent property "colro""}.

Note that this function returns immediately, and therefore may not work if the qml string loads new components (that is, external QML files that have not yet been loaded). If this is the case, consider using Qt.createComponent() instead.

See Dynamic QML Object Creation from JavaScript for more information on using this function.

Returns a color darker than baseColor by the factor provided.

If the factor is greater than 1.0, this function returns a darker color. Setting factor to 3.0 returns a color that has one-third the brightness. If the factor is less than 1.0, the return color is lighter, but we recommend using the Qt.lighter() function for this purpose. If the factor is 0 or negative, the return value is unspecified.

The function converts the current RGB color to HSV, divides the value (V) component by factor and converts the color back to RGB.

If factor is not supplied, returns a color 50% darker than baseColor (factor 2.0).

Returns a Font with the properties specified in the fontSpecifier object or the nearest matching font. The fontSpecifier object should contain key-value pairs where valid keys are the font type's subproperty names, and the values are valid values for each subproperty. Invalid keys will be ignored.

Returns a list of the font families available to the application.

Returns a string representation of date, optionally formatted according to format.

The date parameter may be a JavaScript Date object, a date property, a QDate, or QDateTime value. The format parameter may be any of the possible format values as described for Qt.formatDateTime().

If format is not specified, date is formatted using Qt.DefaultLocaleShortDate.

See also Locale.

Returns a string representation of datetime, optionally formatted according to format.

The date parameter may be a JavaScript Date object, a date property, a QDate, QTime, or QDateTime value.

If format is not provided, dateTime is formatted using Qt.DefaultLocaleShortDate. Otherwise, format should be either:

• One of the Qt::DateFormat enumeration values, such as Qt.DefaultLocaleShortDate or Qt.ISODate
• A string that specifies the format of the returned string, as detailed below.

If format specifies a format string, it should use the following expressions to specify the date:

In addition the following expressions can be used to specify the time:

All other input characters will be ignored. Any sequence of characters that are enclosed in single quotes will be treated as text and not be used as an expression. Two consecutive single quotes ("''") are replaced by a single quote in the output.

For example, if the following date/time value was specified:

// 21 May 2001 14:13:09
var dateTime = new Date(2001, 5, 21, 14, 13, 09)

This dateTime value could be passed to Qt.formatDateTime(), Qt.formatDate() or Qt.formatTime() with the format values below to produce the following results:

See also Locale.

Returns a string representation of time, optionally formatted according to format.

The time parameter may be a JavaScript Date object, a QTime, or QDateTime value. The format parameter may be any of the possible format values as described for Qt.formatDateTime().

If format is not specified, time is formatted using Qt.DefaultLocaleShortDate.

See also Locale.

Returns a color with the specified hue, saturation, lightness and alpha components. All components should be in the range 0-1 inclusive.

Includes another JavaScript file. This method can only be used from within JavaScript files, and not regular QML files.

This imports all functions from url into the current script's namespace.

Qt.include() returns an object that describes the status of the operation. The object has a single property, status, that is set to one of the following values:

The status property will be updated as the operation progresses.

If provided, callback is invoked when the operation completes. The callback is passed the same object as is returned from the Qt.include() call.

Returns true if object is a valid reference to a Qt or QML object, otherwise false.

Returns a color lighter than baseColor by the factor provided.

If the factor is greater than 1.0, this functions returns a lighter color. Setting factor to 1.5 returns a color that is 50% brighter. If the factor is less than 1.0, the return color is darker, but we recommend using the Qt.darker() function for this purpose. If the factor is 0 or negative, the return value is unspecified.

The function converts the current RGB color to HSV, multiplies the value (V) component by factor and converts the color back to RGB.

If factor is not supplied, returns a color 50% lighter than baseColor (factor 1.5).

Returns a JS object representing the locale with the specified name, which has the format "language[_territory][.codeset][@modifier]" or "C", where:

• language is a lowercase, two-letter, ISO 639 language code,
• territory is an uppercase, two-letter, ISO 3166 country code,
• and codeset and modifier are ignored.

If the string violates the locale format, or language is not a valid ISO 369 code, the "C" locale is used instead. If country is not present, or is not a valid ISO 3166 code, the most appropriate country is chosen for the specified language.

See also Locale.

Returns a hex string of the md5 hash of data.

Returns a Matrix4x4 with the specified values. Alternatively, the function may be called with a single argument where that argument is a JavaScript array which contains the sixteen matrix values.

Attempts to open the specified target url in an external application, based on the user's desktop preferences. Returns true if it succeeds, and false otherwise.

Returns a Point with the specified x and y coordinates.

Returns a translated version of sourceText, optionally based on a disambiguation string and value of n for strings containing plurals; otherwise returns sourceText itself if no appropriate translated string is available.

If the same sourceText is used in different roles within the same translation context, an additional identifying string may be passed in for disambiguation.

Example:

Text { text: qsTr("hello") }

See also Internationalization and Localization with Qt Quick.

Returns a translated string identified by id. If no matching string is found, the id itself is returned. This should not happen under normal conditions.

If n >= 0, all occurrences of %n in the resulting string are replaced with a decimal representation of n. In addition, depending on n's value, the translation text may vary.

Example:

Text { text: qsTrId("hello_id") }

It is possible to supply a source string template like:

//% <string>

or

\begincomment% <string> \endcomment

Example:

Text {
//% "hello"
text: qsTrId("hello_id")
}

Creating binary translation (QM) files suitable for use with this function requires passing the -idbased option to the lrelease tool.

See also QT_TRID_NOOP() and Internationalization and Localization with Qt Quick.

Marks id for dynamic translation.

Returns the id.

QT_TRID_NOOP is used in conjunction with the dynamic translation function qsTrId(). It identifies a string as requiring translation (so it can be identified by lupdate), but leaves the actual translation to qsTrId().

Example:

Item {
property string greetingId: QT_TRID_NOOP("hello_id")
Text { text: qsTrId(greetingId) }
}

See also qsTrId() and Internationalization and Localization with Qt Quick.

Marks sourceText for dynamic translation; i.e, the stored sourceText will not be altered.

If the same sourceText is used in different roles within the same translation context, an additional identifying string may be passed in for disambiguation.

Returns the sourceText.

QT_TR_NOOP is used in conjunction with the dynamic translation functions qsTr() and qsTranslate(). It identifies a string as requiring translation (so it can be identified by lupdate), but leaves the actual translation to the dynamic functions.

Example:

Item {
property string greeting: QT_TR_NOOP("hello")
Text { text: qsTr(greeting) }
}

See also Internationalization and Localization with Qt Quick.

Returns a translated version of sourceText within the given context, optionally based on a disambiguation string and value of n for strings containing plurals; otherwise returns sourceText itself if no appropriate translated string is available.

If the same sourceText is used in different roles within the same translation context, an additional identifying string may be passed in for disambiguation.

Example:

Text { text: qsTranslate("CustomContext", "hello") }

See also Internationalization and Localization with Qt Quick.

Marks sourceText for dynamic translation in the given context; i.e, the stored sourceText will not be altered.

If the same sourceText is used in different roles within the same translation context, an additional identifying string may be passed in for disambiguation.

Returns the sourceText.

QT_TRANSLATE_NOOP is used in conjunction with the dynamic translation functions qsTr() and qsTranslate(). It identifies a string as requiring translation (so it can be identified by lupdate), but leaves the actual translation to the dynamic functions.

Example:

Item {
property string greeting: QT_TRANSLATE_NOOP("CustomContext", "hello")
Text { text: qsTranslate("CustomContext", greeting) }
}

See also Internationalization and Localization with Qt Quick.

Returns a Quaternion with the specified scalar, x, y, and z.

This function causes the QQmlEngine::quit() signal to be emitted. Within the Prototyping with qmlscene, this causes the launcher application to exit; to quit a C++ application when this method is called, connect the QQmlEngine::quit() signal to the QCoreApplication::quit() slot.

Returns a rect with the top-left corner at x, y and the specified width and height.

The returned object has x, y, width and height attributes with the given values.

Returns url resolved relative to the URL of the caller.

Returns a color with the specified red, green, blue and alpha components. All components should be in the range 0-1 inclusive.

Returns a Size with the specified width and height.

This function allows tinting one color with another.

The tint color should usually be mostly transparent, or you will not be able to see the underlying color. The below example provides a slight red tint by having the tint color be pure red which is only 1/16th opaque.

Item {
Rectangle {
x: 0; width: 80; height: 80
color: "lightsteelblue"
}
Rectangle {
x: 100; width: 80; height: 80
color: Qt.tint("lightsteelblue", "#10FF0000")
}
}

src="https://assets.ubuntu.com/v1/00e6890f-declarative-rect_tint.png" alt="" />

Tint is most useful when a subtle change is intended to be conveyed due to some event; you can then use tinting to more effectively tune the visible color.

Returns a Vector2D with the specified x and y.

Returns a Vector3D with the specified x, y and z.

Returns a Vector4D with the specified x, y, z and w.