Qt 5.11 | Qt Quick Controls | QML Types | TreeView QML Type

Qt 5.11.3 Reference Documentation

# TreeView QML Type

Provides a tree view with scroll bars, styling and header sections. More...

Import Statement: | import QtQuick.Controls 1.4
Since: | Qt 5.5
Inherits: | ScrollView

- List of all members, including inherited members

## Properties

- currentIndex : QModelIndex
- itemDelegate : Component
- model : QAbstractItemModel
- rootIndex : QModelIndex
- section
  - section.property : string
  - section.criteria : enumeration
  - section.delegate : Component
  - section.labelPositioning : enumeration
- selection : ItemSelectionModel

## Signals

- activated(QModelIndex index)
- clicked(QModelIndex index)
- collapsed(QModelIndex index)
- doubleClicked(QModelIndex index)
- expanded(QModelIndex index)
- pressAndHold(QModelIndex index)

## Methods

- void collapse(QModelIndex index)
- void expand(QModelIndex index)
- QModelIndex indexAt( int x, int y)
- bool isExpanded(QModelIndex index)

## Detailed Description

A TreeView implements a tree representation of items from a model.

Data for each row in the TreeView is provided by the model. TreeView accepts models derived from the QAbstractItemModel class.

You provide title and size of a column header by adding a TableViewColumn as demonstrated below.

      TreeView {
          TableViewColumn {
              title: "Name"
              role: "fileName"
              width: 300
          }
          TableViewColumn {
              title: "Permissions"
              role: "filePermissions"
              width: 100
          }
          model: fileSystemModel
      }

The header sections are attached to values in the model by defining the model role they attach to. Each property in the model will then be shown in their corresponding column.

You can customize the look by overriding the itemDelegate, rowDelegate, or headerDelegate properties.

The view itself does not provide sorting. This has to be done on the model itself. However you can provide sorting on the model, and enable sort indicators on headers.

- int sortIndicatorColumn - The index of the current sort column
- bool sortIndicatorVisible - Whether the sort indicator should be enabled
- enum sortIndicatorOrder - Qt.AscendingOrder or Qt.DescendingOrder depending on state

You can create a custom appearance for a TreeView by assigning a TreeViewStyle.

## Property Documentation

currentIndex : QModelIndex

The model index of the current row in the tree view.

itemDelegate : Component

This property defines a delegate to draw a specific cell.

In the item delegate you have access to the following special properties:

- styleData.selected - if the item is currently selected
- styleData.value - the value or text for this item
- styleData.textColor - the default text color for an item
- styleData.row - the index of the view row
- styleData.column - the index of the view column
- styleData.elideMode - the elide mode of the column
- styleData.textAlignment - the horizontal text alignment of the column
- styleData.pressed - true when the item is pressed
- styleData.hasActiveFocus - true when the row has focus
- styleData.index - the QModelIndex of the current item in the model
- styleData.depth - the depth of the current item in the model
- styleData.isExpanded - true when the item is expanded
- styleData.hasChildren - true if the model index of the current item has or can have children
- styleData.hasSibling - true if the model index of the current item has a sibling

Example:

      itemDelegate: Item {
          Text {
              anchors.verticalCenter: parent.verticalCenter
              color: styleData.textColor
              elide: styleData.elideMode
              text: styleData.value
          }
      }

Note: For performance reasons, created delegates can be recycled across multiple table rows. This implies that when you make use of implicit properties such as `styleData.row` or `model`, these values can change after the delegate has been constructed. This means that you should not assume that content is fixed when `Component.onCompleted` is called, but instead rely on bindings to such properties.

model : QAbstractItemModel

This property holds the model providing data for the tree view.

The model provides the set of data that is displayed by the view. The TreeView accept models derived from the QAbstractItemModel class.

rootIndex : QModelIndex

The model index of the root item in the tree view. The root item is the parent item to the view's top-level items. Only items descending from the root item will be visible in the view.

Its default value is an invalid QModelIndex, which means the whole model data is shown by the tree view (assigning `undefined` to this proprety resets it to its default value.)

This property was introduced in QtQuick.Controls 1.5.

section group
section.property : string
section.criteria : enumeration
section.delegate : Component
section.labelPositioning : enumeration

These properties determine the section labels.

See also ListView.section.

selection : ItemSelectionModel

By default the selection model is `null` and only single selection is supported.

To use a different selection mode as described in selectionMode, an ItemSelectionModel must by set to the selection.

For example:

      TreeView {
         model: myModel
         selection: ItemSelectionModel {
              model: myModel
         }
         TableViewColumn {
             role: "name"
             title: "Name
         }
      }

See also selectionMode.

## Signal Documentation

activated(QModelIndex index)

Emitted when the user activates a row in the tree by mouse or keyboard interaction. Mouse activation is triggered by single- or double-clicking, depending on the platform.

index is the model index of the activated row in the tree.

Note: This signal is only emitted for mouse interaction that is not blocked in the row or item delegate.

The corresponding handler is `onActivated`.

clicked(QModelIndex index)

Emitted when the user clicks a valid row in the tree by single clicking

index is the model index of the clicked row in the tree.

Note: This signal is only emitted if the row or item delegate does not accept mouse events.

The corresponding handler is `onClicked`.

collapsed(QModelIndex index)

Emitted when a valid row in the tree is collapsed, hiding its children.

index is the model index of the collapsed row in the tree.

Note: This signal is only emitted if the row or item delegate does not accept mouse events.

The corresponding handler is `onCollapsed`.

doubleClicked(QModelIndex index)

Emitted when the user double clicks a valid row.

index is the model index of the double clicked row in the tree.

Note: This signal is only emitted if the row or item delegate does not accept mouse events.

The corresponding handler is `onDoubleClicked`.

expanded(QModelIndex index)

Emitted when a valid row in the tree is expanded, displaying its children.

index is the model index of the expanded row in the tree.

Note: This signal is only emitted if the row or item delegate does not accept mouse events.

The corresponding handler is `onExpanded`.

pressAndHold(QModelIndex index)

Emitted when the user presses and holds a valid row in the tree.

index is the model index of the pressed row in the tree.

Note: This signal is only emitted if the row or item delegate does not accept mouse events.

The corresponding handler is `onPressAndHold`.

## Method Documentation

void collapse(QModelIndex index)

Collapses the model item specified by the index.

See also collapsed and isExpanded.

void expand(QModelIndex index)

Expands the model item specified by the index.

See also expanded and isExpanded.

QModelIndex indexAt( int x, int y)

Returns the model index of the visible row at the point x, y in content coordinates. If there is no visible row at the point specified, an invalid QModelIndex is returned.

Note: This method should only be called after the component has completed.

bool isExpanded(QModelIndex index)

Returns true if the model item index is expanded; otherwise returns false.

See also expanded and expand.