- Qt 6.11
- Qt Graphs
- QML Types
- QtGraphs
- Surface3D
- Qt Graphs | Commercial or GPLv3

# Surface3D QML Type

Describes the usage of the 3D surface graph. More...

Import Statement: | `import QtGraphs`
Inherits: | GraphsItem3D

- List of all members, including inherited members
- Surface3D is part of Qt Graphs QML Types for 3D.

## Properties

- ambientLightStrength : real
- aspectRatio : real
- axisX : Value3DAxis
- axisY : Value3DAxis
- axisZ : Value3DAxis
- cameraPreset : Graphs3D.CameraPreset
- cameraTargetPosition : vector3d
- cameraXRotation : real
- cameraYRotation : real
- cameraZoomLevel : real
- currentFps : int
- customItemList : list<Custom3DItem>
- cutoffMargin : real `(since 6.11)`
- flipHorizontalGrid : bool
- gridLineType : Graphs3D.GridLineType
- horizontalAspectRatio : real
- labelMargin : real
- lightColor : color
- lightStrength : real
- locale : locale
- margin : real
- maxCameraXRotation : real `(since 6.9)`
- maxCameraYRotation : real `(since 6.9)`
- maxCameraZoomLevel : real
- measureFps : bool
- minCameraXRotation : real `(since 6.9)`
- minCameraYRotation : real `(since 6.9)`
- minCameraZoomLevel : real
- msaaSamples : int
- optimizationHint : Graphs3D.OptimizationHint
- orthoProjection : bool
- polar : bool
- queriedGraphPosition : vector3d
- radialLabelOffset : real
- renderingMode : Graphs3D.RenderingMode
- rootNode : Node `(since 6.9)`
- rotationEnabled : bool
- scene : Scene3D
- selectedElement : Graphs3D.ElementType
- selectedSeries : Surface3DSeries
- selectionEnabled : bool
- selectionMode : Graphs3D.SelectionMode
- seriesList : list<Surface3DSeries>
- shadowQuality : Graphs3D.ShadowQuality
- shadowStrength : real
- theme : GraphsTheme
- transparencyTechnique : Graphs3D.TransparencyTechnique `(since 6.9)`
- wrapCameraXRotation : bool
- wrapCameraYRotation : bool
- zoomAtTargetEnabled : bool
- zoomEnabled : bool

## Signals

- axisXChanged(ValueAxis3D axis)
- axisYChanged(ValueAxis3D axis)
- axisZChanged(ValueAxis3D axis)
- doubleTapped(QEventPoint eventPoint, Qt::MouseButton button)
- dragged(QVector2D delta)
- flipHorizontalGridChanged(bool flip)
- longPressed()
- mouseMove(QPoint mousePos)
- pinch(qreal delta)
- selectedSeriesChanged(Surface3DSeries series)
- tapped(QEventPoint eventPoint, Qt::MouseButton button)
- wheel(QQuickWheelEvent *event)

## Methods

- qsizetype addCustomItem(Custom3DItem item)
- void addSeries(Surface3DSeries series)
- void clearSelection()
- void doPicking(QPoint point)
- void doRayPicking(QVector3D origin, QVector3D direction)
- bool hasSeries(Abstract3DSeries series)
- void releaseCustomItem(Custom3DItem item)
- void removeCustomItem(Custom3DItem item)
- void removeCustomItemAt(vector3d position)
- void removeCustomItems()
- void removeSeries(Surface3DSeries series)
- void removeSeries(Surface3DSeries series)
- void renderSliceToImage(int index, int requestedIndex, QtGraphs3D::SliceCaptureType sliceType, QUrl filePath) `(since 6.10)`
- Abstract3DAxis selectedAxis()
- Custom3DItem selectedCustomItem()
- qsizetype selectedCustomItemIndex()
- int selectedLabelIndex()

## Detailed Description

This type enables developers to render surface plots in 3D with Qt Quick.

You will need to import the Qt Graphs module to use this type:

     import QtGraphs

After that you can use Surface3D in your qml files:

     import QtQuick
     import QtGraphs

     Item {
         width: 640
         height: 480

         Surface3D {
             width: parent.width
             height: parent.height
             Surface3DSeries {
                 itemLabelFormat: "Pop density at (@xLabel N, @zLabel E): @yLabel"
                 ItemModelSurfaceDataProxy {
                     itemModel: dataModel
                     // Mapping model roles to surface series rows, columns, and values.
                     rowRole: "longitude"
                     columnRole: "latitude"
                     yPosRole: "pop_density"
                 }
             }

             onTapped: {
                 // Disable the default input handler
                 unsetDefaultTapHandler()
                 // Implement own custom event handler
                 console.log("Custom tap event handler")
             }
         }
         ListModel {
             id: dataModel
             ListElement{ longitude: "20"; latitude: "10"; pop_density: "4.75"; }
             ListElement{ longitude: "21"; latitude: "10"; pop_density: "3.00"; }
             ListElement{ longitude: "22"; latitude: "10"; pop_density: "1.24"; }
             ListElement{ longitude: "23"; latitude: "10"; pop_density: "2.53"; }
             ListElement{ longitude: "20"; latitude: "11"; pop_density: "2.55"; }
             ListElement{ longitude: "21"; latitude: "11"; pop_density: "2.03"; }
             ListElement{ longitude: "22"; latitude: "11"; pop_density: "3.46"; }
             ListElement{ longitude: "23"; latitude: "11"; pop_density: "5.12"; }
             ListElement{ longitude: "20"; latitude: "12"; pop_density: "1.37"; }
             ListElement{ longitude: "21"; latitude: "12"; pop_density: "2.98"; }
             ListElement{ longitude: "22"; latitude: "12"; pop_density: "3.33"; }
             ListElement{ longitude: "23"; latitude: "12"; pop_density: "3.23"; }
             ListElement{ longitude: "20"; latitude: "13"; pop_density: "4.34"; }
             ListElement{ longitude: "21"; latitude: "13"; pop_density: "3.54"; }
             ListElement{ longitude: "22"; latitude: "13"; pop_density: "1.65"; }
             ListElement{ longitude: "23"; latitude: "13"; pop_density: "2.67"; }
         }
     }

See Surface Graph Gallery for more thorough usage example.

See also Surface3DSeries, ItemModelSurfaceDataProxy, Bars3D, Scatter3D, and Qt Graphs C++ Classes for 3D.

## Property Documentation

### ambientLightStrength : real

The ambient light strength for the whole graph. This value determines how evenly and brightly the colors are shown throughout the graph regardless of the light position. The value must be between `0.0` and `1.0`.

### aspectRatio : real

The ratio of the graph scaling between the longest axis on the horizontal plane and the y-axis. Defaults to `2.0`.

Note: Has no effect on Bars3D.

See also horizontalAspectRatio.

### axisX : Value3DAxis

The active x-axis.

If an axis is not given, a temporary default axis with no labels and an automatically adjusting range is created. This temporary axis is destroyed if another axis is explicitly set to the same orientation.

### axisY : Value3DAxis

The active y-axis.

If an axis is not given, a temporary default axis with no labels and an automatically adjusting range is created. This temporary axis is destroyed if another axis is explicitly set to the same orientation.

### axisZ : Value3DAxis

The active z-axis.

If an axis is not given, a temporary default axis with no labels and an automatically adjusting range is created. This temporary axis is destroyed if another axis is explicitly set to the same orientation.

### cameraPreset : Graphs3D.CameraPreset

The currently active camera preset, which is one of Graphs3D.CameraPreset. If no preset is active, the value is `Graphs3D.CameraPreset.NoPreset`.

### cameraTargetPosition : vector3d

The camera target as a vector3d. Defaults to `vector3d(0.0, 0.0, 0.0)`.

Valid coordinate values are between `-1.0...1.0`, where the edge values indicate the edges of the corresponding axis range. Any values outside this range are clamped to the edge.

### cameraXRotation : real

The X-rotation angle of the camera around the target point in degrees starting from the current base position.

### cameraYRotation : real

The Y-rotation angle of the camera around the target point in degrees starting from the current base position.

### cameraZoomLevel : real

The camera zoom level in percentage. The default value of `100.0` means there is no zoom in or out set in the camera. The value is limited by the minCameraZoomLevel and maxCameraZoomLevel properties.

See also minCameraZoomLevel and maxCameraZoomLevel.

### currentFps : int

When FPS measuring is enabled, the results for the last second are stored in this read-only property. It takes at least a second before this value updates after measuring is activated.

See also measureFps.

### customItemList : list<Custom3DItem>

The list of Custom3DItem items added to the graph. The graph takes ownership of the added items.

### cutoffMargin : real `[since 6.11]`

The value used for the difference between the axis limits and the position at which graph elements are culled.

Note: Does not affect bar graphs.

This property was introduced in Qt 6.11.

### flipHorizontalGrid : bool

In some use cases the horizontal axis grid is mostly covered by the surface, so it can be more useful to display the horizontal axis grid on top of the graph rather than on the bottom. A typical use case for this is showing 2D spectrograms using orthoGraphic projection with a top-down viewpoint.

If `false`, the horizontal axis grid and labels are drawn on the horizontal background of the graph. If `true`, the horizontal axis grid and labels are drawn on the opposite side of the graph from the horizontal background. Defaults to `false`.

### gridLineType : Graphs3D.GridLineType

Defines whether the grid lines type is `Graphs3D.GridLineType.Shader` or `Graphs3D.GridLineType.Geometry`.

This value affects all grid lines.

See also Graphs3D.GridLineType.

### horizontalAspectRatio : real

The ratio of the graph scaling between the x-axis and z-axis. The value of `0.0` indicates automatic scaling according to axis ranges. Defaults to `0.0`.

Note: Has no effect on Bars3D, which handles scaling on the horizontal plane via the barThickness and barSpacing properties. Polar graphs also ignore this property.

See also aspectRatio, polar, Bars3D::barThickness, and Bars3D::barSpacing.

### labelMargin : real

This property specifies the margin for the placement of the axis labels.

Negative values place the labels inside the plot-area while positive values place them outside the plot-area. Label automatic rotation is disabled when the value is negative. Defaults to `0.1`

See also QAbstract3DAxis::labelAutoAngle.

### lightColor : color

The color of the ambient and specular light defined in Scene3D.

### lightStrength : real

The specular light strength for the whole graph. The value must be between `0.0` and `10.0`.

This value affects the light specified in Scene3D.

### locale : locale

Sets the locale used for formatting various numeric labels. Defaults to the `"C"` locale.

See also Value3DAxis::labelFormat.

### margin : real

The absolute value used for the space left between the edge of the plottable graph area and the edge of the graph background.

If the margin value is negative, the margins are determined automatically and can vary according to the size of the items in the series and the type of the graph. The value is interpreted as a fraction of the y-axis range if the graph aspect ratios have not been changed from the default values. Defaults to `-1.0`.

Note: Setting a smaller margin for a scatter graph than the automatically determined margin can cause the scatter items at the edges of the graph to overlap with the graph background.

Note: On scatter and surface graphs, if the margin is small in comparison to the axis label size, the positions of the edge labels of the axes are adjusted to avoid overlap with the edge labels of the neighboring axes.

### maxCameraXRotation : real `[since 6.9]`

The maximum X-rotation angle of the camera around the target point in degrees. The default value is `180.0`

This property was introduced in Qt 6.9.

### maxCameraYRotation : real `[since 6.9]`

The maximum Y-rotation angle of the camera around the target point in degrees. The default value is `90.0`

This property was introduced in Qt 6.9.

### maxCameraZoomLevel : real

Sets the maximum allowed camera zoom level. If the new maximum level is lower than the existing minimum level, the minimum level is adjusted to the new maximum as well. If the current cameraZoomLevel is outside the new bounds, it is adjusted as well. Defaults to `500.0f`.

See also cameraZoomLevel and minCameraZoomLevel.

### measureFps : bool

If `true`, the rendering is done continuously instead of on demand, and the value of the currentFps property is updated. Defaults to `false`.

See also currentFps.

### minCameraXRotation : real `[since 6.9]`

The minimum X-rotation angle of the camera around the target point in degrees. The default value is `-180.0`

This property was introduced in Qt 6.9.

### minCameraYRotation : real `[since 6.9]`

The minimum Y-rotation angle of the camera around the target point in degrees. The default value is `0.0`

This property was introduced in Qt 6.9.

### minCameraZoomLevel : real

Sets the minimum allowed camera zoom level. If the new minimum level is higher than the existing maximum level, the maximum level is adjusted to the new minimum as well. If the current cameraZoomLevel is outside the new bounds, it is adjusted as well. The minCameraZoomLevel cannot be set below `1.0`. Defaults to `10.0`.

See also cameraZoomLevel and maxCameraZoomLevel.

### msaaSamples : int

The number of samples used in multisample antialiasing when renderingMode is `Indirect`. When renderingMode is `DirectToBackground`, this property value is read-only and returns the number of samples specified by the window surface format. Defaults to `4`.

See also renderingMode.

### optimizationHint : Graphs3D.OptimizationHint

Specifies whether the default or legacy mode is used for rendering optimization.

The default mode uses instanced rendering, and provides the full feature set at the best level of performance on most systems. The static mode optimizes graph rendering and is ideal for large non-changing data sets. It is slower with dynamic data changes and item rotations. Selection is not optimized, so using the static mode with massive data sets is not advisable. Legacy mode renders all items in th graph individually, without instancing. It should be used only if default mode does not work, that is the same as if the target system does not support instancing. Defaults to Default.

Note: On some environments, large graphs using static optimization may not render, because all of the items are rendered using a single draw call, and different graphics drivers support different maximum vertice counts per call. This is mostly an issue on 32bit and OpenGL ES2 platforms. To work around this issue, choose an item mesh with a low vertex count or use the point mesh.

See also Abstract3DSeries::mesh and Graphs3D.OptimizationHint.

### orthoProjection : bool

If `true`, orthographic projection will be used for displaying the graph. Defaults to `false`.

Note: Shadows will be disabled when set to `true`.

### polar : bool

If `true`, the horizontal axes are changed into polar axes. The x-axis becomes the angular axis and the z-axis becomes the radial axis. Polar mode is not available for bar graphs.

Defaults to `false`.

See also orthoProjection and radialLabelOffset.

### queriedGraphPosition : vector3d `[read-only]`

This read-only property contains the latest graph position values along each axis queried using Scene3D::graphPositionQuery. The values are normalized to range `[-1, 1]`. If the queried position was outside the graph bounds, the values will not reflect the real position, but will instead be some undefined position outside the range `[-1, 1]`. The value will be undefined until a query is made.

There is no single correct 3D coordinate to match a particular screen position, so to be consistent, the queries are always done against the inner sides of an invisible box surrounding the graph.

Note: Bar graphs only allow querying graph position at the graph floor level, so the y-value is always zero for bar graphs and valid queries can be only made at screen positions that contain the floor of the graph.

See also Scene3D::graphPositionQuery.

### radialLabelOffset : real

This property specifies the normalized horizontal offset for the axis labels of the radial polar axis. The value `0.0` indicates that the labels should be drawn next to the 0-angle angular axis grid line. The value `1.0` indicates that the labels are drawn in their usual place at the edge of the graph background. This property is ignored if the polar property value is `false`. Defaults to `1.0`.

See also polar.

### renderingMode : Graphs3D.RenderingMode

How the graph will be rendered. Defaults to `Indirect`.

Note: Setting the `antialiasing` property of the graph does not do anything. However, it is set by the graph itself if the current rendering mode uses antialiasing.

See also msaaSamples and Graphs3D.RenderingMode.

### rootNode : Node `[read-only, since 6.9]`

Returns a pointer to the root node of the 3D graph. Use this property for injecting a 3D graph into a separate View3D using importScene:

     Bars3D {
       id: bars
     }
     View3D {
       importScene: bars.rootNode
     }

This property was introduced in Qt 6.9.

See also View3D.

### rotationEnabled : bool

Whether this input handler allows graph rotation.

Defaults to `true`.

### scene : Scene3D `[read-only]`

The Scene3D pointer that can be used to manipulate the scene and access the scene elements.

This property is read-only.

### selectedElement : Graphs3D.ElementType `[read-only]`

The element selected in the graph.

This property can be used to query the selected element type. The type is valid until a new selection is made in the graph and the `selectedElementChanged` signal is emitted.

The signal can be used for example for implementing customized input handling, as demonstrated by the Axis Handling example.

See also selectedLabelIndex(), selectedAxis(), selectedCustomItemIndex(), selectedCustomItem(), Bars3D::selectedSeries, Scatter3D::selectedSeries, Scene3D::selectionQueryPosition, and Graphs3D.ElementType.

### selectedSeries : Surface3DSeries `[read-only]`

The selected series or null. If selectionMode has the `MultiSeries` flag set, this property holds the series which owns the selected point.

### selectionEnabled : bool

Whether this input handler allows selection from the graph.

Defaults to `true`.

### selectionMode : Graphs3D.SelectionMode

The active selection mode in the graph. One of the Graphs3D.SelectionFlag enum values.

### seriesList : list<Surface3DSeries> `[default]`

This property holds the series of the graph. By default, this property contains an empty list. To set the series, either use the addSeries() function or define them as children of the graph.

### shadowQuality : Graphs3D.ShadowQuality

The quality of shadows. One of the Graphs3D.ShadowQuality enum values.

### shadowStrength : real

The shadow strength for the whole graph. The higher the number, the darker the shadows will be. The value must be between `0.0` and `100.0`.

This value affects the light specified in Scene3D.

### theme : GraphsTheme

The active theme of the graph.

See also GraphsTheme.

### transparencyTechnique : Graphs3D.TransparencyTechnique `[since 6.9]`

Specifies which transparency technique to use. The Default value is `Default`. When rendering transparent surface graphs, use `Approximate` or `Accurate`. `Default` should be used for other graph types.

Constant | Description
--- | ---
`Default` | Indicates that order-independent transparency techniques are not used. Offers the best performance. Use when graphs don't contain transparency or when a bar or scatter graph is also using instancing, that is optimizationHint is {QtGraphs3D::OptimizationHint::Default}.
`Approximate` | Indicates that a graph attempts an approximation of order-independent transparency. This method is faster than `Accurate` and works on older hardware but may yield inaccurate results. Use when the order-independent transparency is needed, but the performance cost has to be lower than when using accurate order-independent transparency.
`Accurate` | Indicates that accurate order-independent transparency is used. Use when perfect transparency rendering is needed.

This property was introduced in Qt 6.9.

### wrapCameraXRotation : bool

The behavior of the minimum and maximum limits in the X-rotation. By default, the X-rotation wraps from minimum value to maximum and from maximum to minimum.

If set to `true`, the X-rotation of the camera is wrapped from minimum to maximum and from maximum to minimum. If set to `false`, the X-rotation of the camera is limited to the sector determined by the minimum and maximum values.

### wrapCameraYRotation : bool

The behavior of the minimum and maximum limits in the Y-rotation. By default, the Y-rotation is limited between the minimum and maximum values without any wrapping.

If `true`, the Y-rotation of the camera is wrapped from minimum to maximum and from maximum to minimum. If `false`, the Y-rotation of the camera is limited to the sector determined by the minimum and maximum values.

### zoomAtTargetEnabled : bool

Whether zooming should change the camera target so that the zoomed point of the graph stays at the same location after the zoom.

Defaults to `true`.

### zoomEnabled : bool

Whether this input handler allows graph zooming.

Defaults to `true`.

## Signal Documentation

### axisXChanged(ValueAxis3D axis)

This signal is emitted when axisX changes to axis.

Note: The corresponding handler is `onAxisXChanged`.

### axisYChanged(ValueAxis3D axis)

This signal is emitted when axisY changes to axis.

Note: The corresponding handler is `onAxisYChanged`.

### axisZChanged(ValueAxis3D axis)

This signal is emitted when axisZ changes to axis.

Note: The corresponding handler is `onAxisZChanged`.

### doubleTapped(QEventPoint eventPoint, Qt::MouseButton button)

This signal is emitted when the graph item is tapped twice within a short span of time. The eventPoint signal parameter contains information from the release event about the point that was tapped, and button is the mouse button that was clicked, or `NoButton` on a touchscreen.

Note: The corresponding handler is `onDoubleTapped`.

See also QEventPoint, Qt::MouseButtons, and TapHandler::doubleTapped.

### dragged(QVector2D delta)

This signal is emitted when the translation of the cluster of points on the graph is changed while the pinch gesture is being performed. The delta vector gives the change in translation.

Note: The corresponding handler is `onDragged`.

See also PinchHandler::translationChanged.

### flipHorizontalGridChanged(bool flip)

This signal is emitted when flipHorizontalGrid changes to flip.

Note: The corresponding handler is `onFlipHorizontalGridChanged`.

### longPressed()

This signal is emitted when the `parent` Item is pressed and held for a time period greater than TapHandler::longPressThreshold.

Note: The corresponding handler is `onLongPressed`.

See also TapHandler::longPressed.

### mouseMove(QPoint mousePos)

This signal is emitted when the graph receives a mouseMove event. mousePos value gives the position of mouse while mouse is moving.

Note: The corresponding handler is `onMouseMove`.

See also QQuickItem::mouseMoveEvent.

### pinch(qreal delta)

This signal is emitted when the scale factor on the graph changes while the pinch gesture is being performed. The delta value gives the multiplicative change in scale.

Note: The corresponding handler is `onPinch`.

See also PinchHandler::scaleChanged.

### selectedSeriesChanged(Surface3DSeries series)

This signal is emitted when selectedSeries changes to series.

Note: The corresponding handler is `onSelectedSeriesChanged`.

### tapped(QEventPoint eventPoint, Qt::MouseButton button)

This signal is emitted when the graph item is tapped once. The eventPoint signal parameter contains information from the release event about the point that was tapped, and button is the mouse button that was clicked, or `NoButton` on a touchscreen.

Note: The corresponding handler is `onTapped`.

See also QEventPoint, Qt::MouseButtons, and TapHandler::singleTapped.

### wheel(QQuickWheelEvent *event)

This signal is emitted every time the graph receives an event of type QWheelEvent: that is, every time the wheel is moved or the scrolling gesture is updated.

Note: The corresponding handler is `onWheel`.

See also WheelEvent and WheelHandler::wheel.

## Method Documentation

### qsizetype addCustomItem(Custom3DItem item)

Adds a Custom3DItem item to the graph. Graph takes ownership of the added item.

Returns index to the added item if add was successful, -1 if trying to add a null item, and index of the item if trying to add an already added item.

See also removeCustomItems(), removeCustomItem(), and removeCustomItemAt().

### void addSeries(Surface3DSeries series)

Adds the series to the graph.

See also GraphsItem3D::hasSeries().

### void clearSelection()

Clears selection from all attached series.

### void doPicking(QPoint point)

Performs picking using view coordinates from point on the elements of the graph, selecting the first item hit. Default input handling performs this upon receiving the onTapped event.

See also selectedElement.

### void doRayPicking(QVector3D origin, QVector3D direction)

Performs picking starting from origin and in direction on the elements of the graph, selecting the first item hit.

See also selectedElement.

### bool hasSeries(Abstract3DSeries series)

Returns whether the series has already been added to the graph.

### void releaseCustomItem(Custom3DItem item)

Gets ownership of item back and removes the item from the graph.

Note: If the same item is added back to the graph, the texture file needs to be re-set.

See also Custom3DItem::textureFile.

### void removeCustomItem(Custom3DItem item)

Removes the custom item. Deletes the resources allocated to it.

### void removeCustomItemAt(vector3d position)

Removes all custom items at position. Deletes the resources allocated to them.

### void removeCustomItems()

Removes all custom items. Deletes the resources allocated to them.

### void removeSeries(Surface3DSeries series)

Removes the series from the graph.

See also GraphsItem3D::hasSeries().

### void removeSeries(Surface3DSeries series)

Removes the series from the graph.

See also GraphsItem3D::hasSeries().

### `[since 6.10]` void renderSliceToImage(int index, int requestedIndex, QtGraphs3D::SliceCaptureType sliceType, QUrl filePath)

Exports a 2d slice from series at index and saves the result to an image at a specified filePath. To export all series, set index to -1. The exported slice includes lines of row or column, which is defined by sliceType at a given requestedIndex.

This method was introduced in Qt 6.10.

### Abstract3DAxis selectedAxis()

Can be used to get the selected axis after receiving `selectedElementChanged` signal with any label type. Selection is valid until the next `selectedElementChanged` signal.

Returns the selected axis, or null.

See also selectedElement.

### Custom3DItem selectedCustomItem()

Can be used to get the selected custom item after receiving `selectedElementChanged` signal with ElementType.CustomItem type. Ownership of the item remains with the graph. Selection is valid until the next `selectedElementChanged` signal.

Returns the selected custom item, or null.

See also selectedElement.

### qsizetype selectedCustomItemIndex()

Can be used to query the index of the selected custom item after receiving `selectedElementChanged` signal with ElementType.CustomItem type. Selection is valid until the next `selectedElementChanged` signal.

Returns index of the selected custom item, or -1.

See also selectedElement.

### int selectedLabelIndex()

Can be used to query the index of the selected label after receiving `selectedElementChanged` signal with any label type. Selection is valid until the next `selectedElementChanged` signal.

Returns index of the selected label, or -1.

See also selectedElement.