path: root/doc/qtcreator/src/qtquick/qtquick-properties.qdoc

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/*!
    \page qtquick-properties.html
    \previouspage qtquick-navigator.html
    \nextpage qtquick-fonts.html

    \title Specifying Item Properties

    The \uicontrol Properties view displays all the properties of the selected
    item. The properties are grouped by type. The top part of the view displays
    properties that are common to all QML types, such as position, size, and
    visibility.

    The bottom part of the view displays properties that are specific to each
    QML type. For example, the following image displays the properties you can
    set for \uicontrol Rectangle (1) and \uicontrol Text (2) items.

    \image qmldesigner-element-properties.png

    To change the item type, double-click the \uicontrol Type field in the
    \uicontrol Properties view, and enter the name of another QML type in the
    field. If you have specified properties for the item that are not supported
    for the new type, the type cannot be changed and an error message is
    displayed. Select the \inlineimage icons/action-icon.png
    (\uicontrol Actions) menu next to the property name, and then select
    \uicontrol Reset to remove the property values before trying again.

    To modify the common properties of multiple items simultaneously, select
    them in the \uicontrol Navigator or on the canvas:

    \list
        \li On Windows, press and hold \key Ctrl and \key Shift, and then click
            the items to select them.
        \li On \macos, press \key Shift to select a range of items or \key Cmd
            to select multiple single items.
    \endlist

    To return an item to its implicit position after moving it, select the
    \inlineimage qtcreator-reset-position-icon.png
    (\uicontrol {Reset Position}) button on the toolbar. To return it to its
    implicit size, select \inlineimage qtcreator-reset-size-icon.png
    (\uicontrol {Reset Size}) button.

    To set the visibility of the item, select \uicontrol Edit >
    \uicontrol Visibility in the context menu.

    For more information on the properties available for an item, press
    \key {F1}.

    \section1 Viewing Changes in Properties

    The default values of properties are displayed in white color, while the
    values that you specify explicitly are highlighted with blue color. In
    addition, property changes in states are highlighted with blue.

    This allows you to easily see which values are set in the UI form or QML
    file and which values are default characteristics of a QML type or a
    component.

    When editing states, you can easily see which values are explicitly set in
    the current state and which values are derived from the base state.

    The following images illustrate this. In the base state, the \uicontrol Size
    (1) and \uicontrol Colors (2) values are explicitly set and highlighted.

    \image qmldesigner-properties-explicit-base.png "Explicitly set properties"

    In \uicontrol State1, only the color (1) is explicitly set and highlighted.

    \image qmldesigner-properties-explicit-state1.png "Explicitly set properties"

    Resetting a property sets it back to the default value and removes the value
    from the UI form or QML file.

    \note As a result, all boolean values can be visualized in four different
    ways.

    For example, visibility can be visualized as follows:

    \table
        \row
            \li \image qmldesigner-boolean-true.png
            \li TRUE
            \li The QML type is visible by default. The visibility might be
                overridden by the visibility set in the base state.
        \row
            \li \image qmldesigner-boolean-true-blue.png
            \li TRUE (highlighted)
            \li The QML type is explicitly set to visible.
        \row
            \li \image qmldesigner-boolean-false.png
            \li FALSE
            \li The QML type is hidden by default. The visibility might be
                overridden by the visibility set in the base state.
        \row
            \li \image qmldesigner-boolean-false-blue.png
            \li FALSE (hightlighted)
            \li The type is explicitly set to hidden.
    \endtable

    \section1 Picking Colors

    To specify the color of the selected item in the color picker view (1),
    select the color picker icon (2) in the \uicontrol Properties view.

    \image qtquick-designer-color-picker.png "Color Picker view"

    You can use either a solid color (3) or a gradient (4). You can select the
    gradient in the \uicontrol {Gradient Picker} (5).

    The \uicontrol Original field displays the original color of the item,
    whereas the \uicontrol New field displays the current color. The
    \uicontrol Recent field displays the colors that you have last selected.

    \section1 Picking Gradients

    The \uicontrol {Gradient Picker} enables you to specify
    \l{https://webgradients.com/}{WebGradients} for QML types
    that support \l QGradient.

    To open the \uicontrol {Gradient Picker}, select the
    \uicontrol {Gradient Picker Dialog} icon in the \uicontrol Properties view.

    \image qtquick-designer-gradient-picker.png "Gradient Picker dialog"

    To apply a gradient on the selected item, select \uicontrol Apply.

    To save a gradient in the \uicontrol {User Presets} tab, select
    \uicontrol Save.

    By default, a linear gradient (4) is used, but you can select another
    supported gradient type in the \uicontrol Properties view.

    \section1 Marking Text Items for Translation

    To support translators, mark each text item that should be translated.
    In the \uicontrol Properties view, \uicontrol Text field, select \uicontrol tr (1).

    \image qmldesigner-text-property-tr.png "Text properties"

    By default, the text string is enclosed in a \c qsTr() call.

    \image qml-translate.png "Text marked for translation"

    If you use text IDs instead of plain text, change the default call to
    \c qsTrId(). Select \uicontrol Tools > \uicontrol Options >
    \uicontrol {Qt Quick} > \uicontrol {\QMLD}, and then select the
    \uicontrol {qsTrId()} radio button in the \uicontrol Internationalization
    group. For more information about text ID based translations, see
    \l {Qt Linguist Manual: Text ID Based Translations}.

    To preserve the context when editing the text or to change the context
    by setting a binding on the text property, change the default call to
    \c qsTranslate() by selecting the \uicontrol {qsTranslate()} radio button.

    For more information, see
    \l {Internationalization and Localization with Qt Quick}.

    \if defined(qtcreator)
    When you \l{Creating Qt Quick Projects}{create a new project}, you can
    automatically generate a translation source file (TS) for one language.
    You can add other languages later by editing the project file.
    \endif

    \section1 Loading Placeholder Data

    The Design mode supports views, models, and delegates, so that when you add
    a Grid View, List View, or Path View item, the ListModel and the delegate
    item are added automatically.

    However, the missing context of the application presents a challenge.
    Specific models defined in C++ are the most obvious case. Often,
    the context is missing simple properties, which are either defined in C++,
    or in other QML files. A typical example is an item that uses the
    properties of its parent, such as \c parent.width.

    \section2 Using Dummy Models

    If you open a file in the Design mode that references a C++ model, you see
    nothing on
    the canvas. If the data in the model is fetched from the internet, you have
    no control over it. To get reliable data, \e {dummy data} was introduced.

    For example, the following code snippet describes the file example.qml that
    contains a ListView that in turn specifies a C++ model:

    \qml
        ListView {
            model: dataModel
            delegate: ContactDelegate {
                name: name
            }
        }
    \endqml

    Create a directory named \e dummydata in the root directory of the project,
    so that it is not deployed to the device. In the \c dummydata directory,
    create a QML file that has the same name as the value of \c model:

    \code
        qml/exampleapp/example.qml
        dummydata/dataModel.qml
    \endcode

    Then create the dataModel.qml file that contains the dummy data:

    \qml
        import QtQuick 2.0

        ListModel {
             ListElement {
                 name: "Ariane"
             }
             ListElement {
                 name: "Bella"
             }
             ListElement {
                 name: "Corinna"
             }
        }
    \endqml

    \section2 Creating Dummy Context

    The following example presents a common pattern in QML:

    \qml
        Item {
            width: parent.width
            height: parent.height
        }
    \endqml

    This works nicely for applications but the Design mode displays a zero-sized
    item. A parent for the opened file does not exist, because the context is
    missing. To get around the missing context, the idea of a \e {dummy
    context} is introduced. If you place a file with the same name as the
    application (here, example.qml) in the \c {dummydata/context} directory,
    you can fake a parent context:

    \qml
        import QtQuick 2.0
        import QmlDesigner 1.0

        DummyContextObject {
            parent: Item {
                width: 640
                height: 300
            }
        }
    \endqml

    \section1 Building Transformations on Items

    The \uicontrol Advanced tab allows you to configure advanced
    transformations, such as rotation, scale, and translation. You
    can assign any number of transformations to an item. Each
    transformation is applied in order, one at a time.

    For more information on Transform types, see \l{Transform}.

    \section1 Editing Properties Inline

    You can double-click objects on the canvas to edit their text, color,
    or source properties inline. Because you can specify several of these
    properties for some QML types, such as \l [QML]{TextEdit}{Text Edit},
    you can also right-click objects to open the inline editors from a
    context-menu.

    \image qmldesigner-inline-editing.png
*/