Tumbler QML Type

Spinnable wheel of items that can be selected. 更多...

import 语句：	import QtQuick.Controls
继承：	Control

所有成员列表，包括继承成员

特性

count : int
currentIndex : int
currentItem : Item
delegate : Component
model : variant
moving : bool
visibleItemCount : int
wrap : bool

附加特性

displacement : real
tumbler : Tumbler

方法

void positionViewAtIndex (int index , PositionMode mode )

详细描述

Tumbler {
    model: 5
    // ...
}

Tumbler allows the user to select an option from a spinnable "wheel" of items. It is useful for when there are too many options to use, for example, a RadioButton , and too few options to require the use of an editable SpinBox . It is convenient in that it requires no keyboard usage and wraps around at each end when there are a large number of items.

The API is similar to that of views like ListView and PathView ; a model and delegate can be set, and the count and currentItem properties provide read-only access to information about the view. To position the view at a certain index, use positionViewAtIndex ().

Unlike views like PathView and ListView , however, there is always a current item (when the model isn't empty). This means that when count 等于 0 , currentIndex 将是 -1 . In all other cases, it will be greater than or equal to 0 .

By default, Tumbler wraps when it reaches the top and bottom, as long as there are more items in the model than there are visible items; that is, when count 大于 visibleItemCount :

import QtQuick
import QtQuick.Window
import QtQuick.Controls
Rectangle {
    width: frame.implicitWidth + 10
    height: frame.implicitHeight + 10
    function formatText(count, modelData) {
        var data = count === 12 ? modelData + 1 : modelData;
        return data.toString().length < 2 ? "0" + data : data;
    }
    FontMetrics {
        id: fontMetrics
    }
    Component {
        id: delegateComponent
        Label {
            text: formatText(Tumbler.tumbler.count, modelData)
            opacity: 1.0 - Math.abs(Tumbler.displacement) / (Tumbler.tumbler.visibleItemCount / 2)
            horizontalAlignment: Text.AlignHCenter
            verticalAlignment: Text.AlignVCenter
            font.pixelSize: fontMetrics.font.pixelSize * 1.25
        }
    }
    Frame {
        id: frame
        padding: 0
        anchors.centerIn: parent
        Row {
            id: row
            Tumbler {
                id: hoursTumbler
                model: 12
                delegate: delegateComponent
            }
            Tumbler {
                id: minutesTumbler
                model: 60
                delegate: delegateComponent
            }
            Tumbler {
                id: amPmTumbler
                model: ["AM", "PM"]
                delegate: delegateComponent
            }
        }
    }
}

另请参阅 Customizing Tumbler and 输入控件 .

特性文档编制

[read-only] count : int

This property holds the number of items in the model.

currentIndex : int

This property holds the index of the current item.

The value of this property is -1 当 count 等于 0 . In all other cases, it will be greater than or equal to 0 .

另请参阅 currentItem and positionViewAtIndex ().

[read-only] currentItem : Item

This property holds the item at the current index.

另请参阅 currentIndex and positionViewAtIndex ().

delegate : Component

This property holds the delegate used to display each item.

model : variant

This property holds the model that provides data for this tumbler.

[since QtQuick.Controls 2.2 (Qt 5.9)] moving : bool

This property describes whether the tumbler is currently moving, due to the user either dragging or flicking it.

This property was introduced in QtQuick.Controls 2.2 (Qt 5.9).

visibleItemCount : int

This property holds the number of items visible in the tumbler. It must be an odd number, as the current item is always vertically centered.

[since QtQuick.Controls 2.1 (Qt 5.8)] wrap : bool

This property determines whether or not the tumbler wraps around when it reaches the top or bottom.

默认值为 false 当 count 小于 visibleItemCount , as it is simpler to interact with a non-wrapping Tumbler when there are only a few items. To override this behavior, explicitly set the value of this property. To return to the default behavior, set this property to undefined .

该特性在 QtQuick.Controls 2.1 (Qt 5.8) 引入。

附加特性文档编制

[read-only] Tumbler.displacement : real

This attached property holds a value from -visibleItemCount / 2 to visibleItemCount / 2 , which represents how far away this item is from being the current item, with 0 being completely current.

For example, the item below will be 40% opaque when it is not the current item, and transition to 100% opacity when it becomes the current item:

delegate: Text {
    text: modelData
    opacity: 0.4 + Math.max(0, 1 - Math.abs(Tumbler.displacement)) * 0.6
}

[read-only] Tumbler.tumbler : Tumbler

This attached property holds the tumbler. The property can be attached to a tumbler delegate. The value is null if the item is not a tumbler delegate.

方法文档编制

[since QtQuick.Controls 2.5 (Qt 5.12)] void positionViewAtIndex ( int index , PositionMode mode )

Positions the view so that the index is at the position specified by mode .

例如：

positionViewAtIndex(10, Tumbler.Center)

若 wrap is true (the default), the modes available to PathView 's positionViewAtIndex () function are available, otherwise the modes available to ListView 's positionViewAtIndex () function are available.

注意： There is a known limitation that using Tumbler.Beginning 当 wrap is true will result in the wrong item being positioned at the top of view. As a workaround, pass index - 1 .

This method was introduced in QtQuick.Controls 2.5 (Qt 5.12).

另请参阅 currentIndex .