Qt Reference Documentation

QML Qt Element

The QML global Qt object provides useful enums and functions from Qt. More...

  • List of all members, including inherited members
  • Methods

    Detailed Description

    The Qt object is not a QML element; it cannot be instantiated. It is a global object with enums and functions. To use it, call the members of the global Qt object directly. For example:

     import Qt 4.7
    
     Text {
         color: Qt.rgba(255, 0, 0, 1)
         text: Qt.md5("hello, world")
     }

    Enums

    The Qt object contains enums that declared into Qt's Meta-Object System. For example, you can access the Leftbutton member of the Qt::MouseButton enum with Qt.LeftButton.

    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:

    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.

    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 Object Management in QML for an overview of their use.

    Method Documentation

    string Qt::atob ( data )

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


    string Qt::btoa ( data )

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


    object Qt::createComponent ( url )

    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.

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

    For example:

     import Qt 4.7
    
     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 Object Management in QML 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().


    object Qt::createQmlObject ( string qml, object parent, string filepath )

    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 Qt 4.7; Rectangle {color: "red"; width: 20; height: 20}',
         parentItem, "dynamicSnippet1");

    In the case of an error, a QtScript 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.

    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 Object Management in QML for more information on using this function.


    color Qt::darker ( color baseColor, real factor )

    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).


    list<string> Qt::fontFamilies ()

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


    string Qt::formatDate ( datetime date, variant format )

    Returns the string representation of date, formatted according to format.


    string Qt::formatDateTime ( datetime dateTime, variant format )

    Returns the string representation of dateTime, formatted according to format.

    format for the date/time formatting functions is be specified as follows.

    These expressions may be used for the date:

    ExpressionOutput

    d

    the day as number without a leading zero (1 to 31)

    dd

    the day as number with a leading zero (01 to 31)

    ddd

    the abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses QDate::shortDayName().

    dddd

    the long localized day name (e.g. 'Monday' to 'Qt::Sunday'). Uses QDate::longDayName().

    M

    the month as number without a leading zero (1-12)

    MM

    the month as number with a leading zero (01-12)

    MMM

    the abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses QDate::shortMonthName().

    MMMM

    the long localized month name (e.g. 'January' to 'December'). Uses QDate::longMonthName().

    yy

    the year as two digit number (00-99)

    yyyy

    the year as four digit number

    These expressions may be used for the time:

    ExpressionOutput

    h

    the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)

    hh

    the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)

    m

    the minute without a leading zero (0 to 59)

    mm

    the minute with a leading zero (00 to 59)

    s

    the second without a leading zero (0 to 59)

    ss

    the second with a leading zero (00 to 59)

    z

    the milliseconds without leading zeroes (0 to 999)

    zzz

    the milliseconds with leading zeroes (000 to 999)

    AP

    use AM/PM display. AP will be replaced by either "AM" or "PM".

    ap

    use am/pm display. ap will be replaced by either "am" or "pm".

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

    Example format strings (assumed that the date and time is 21 May 2001 14:13:09):

    FormatResult

    dd.MM.yyyy

    21.05.2001

    ddd MMMM d yy

    Tue May 21 01

    hh:mm:ss.zzz

    14:13:09.042

    h:m:s ap

    2:13:9 pm

    If no format is specified the locale's short format is used. Alternatively, you can specify Qt.DefaultLocaleLongDate to get the locale's long format.


    string Qt::formatTime ( datetime time, variant format )

    Returns the string representation of time, formatted according to format.

    See Qt::formatDateTime for how to define format.


    color Qt::hsla ( real hue, real saturation, real lightness, real alpha )

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


    bool Qt::isQtObject ( object )

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


    color Qt::lighter ( color baseColor, real factor )

    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).


    string Qt::md5 ( data )

    Returns a hex string of the md5 hash of data.


    bool Qt::openUrlExternally ( url target )

    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.


    point Qt::point ( int x, int y )

    Returns a Point with the specified x and y coordinates.


    Qt::quit ()

    This function causes the QDeclarativeEngine::quit() signal to be emitted. Within the QML Viewer, this causes the launcher application to exit.


    rect Qt::rect ( int x, int y, int width, int height )

    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.


    url Qt::resolvedUrl ( url )

    Returns url resolved relative to the URL of the caller.


    color Qt::rgba ( real red, real green, real blue, real alpha )

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


    Qt::size ( int width, int height )

    Returns a Size with the specified width and height.


    color Qt::tint ( color baseColor, color tintColor )

    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.

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

    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.


    Qt::vector3d ( real x, real y, real z )

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


    X

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