java.lang.Object
- eu.webtoolkit.jwt.WObject
- - eu.webtoolkit.jwt.WWidget
  - - eu.webtoolkit.jwt.WCompositeWidget
    - - eu.webtoolkit.jwt.WAbstractItemView
      - eu.webtoolkit.jwt.WTreeView

```
public class WTreeView
extends WAbstractItemView
```
A view class that displays a model as a tree or tree table.
The view displays data from a WAbstractItemModel in a tree or tree table. It provides incremental rendering, allowing the display of data models of any size efficiently, without excessive use of client- or serverside resources.
The rendering (and editing) of items is handled by a WAbstractItemDelegate, by default it uses WItemDelegate which renders data of all predefined roles (see also ItemDataRole), including text, icons, checkboxes, and tooltips.
The view may support editing of items, if the model indicates support (see the ItemFlag.Editable flag). You can define triggers that initiate editing of an item using WAbstractItemView#setEditTriggers(). The actual editing is provided by the item delegate (you can set an appropriate delegate for one column using WAbstractItemView#setItemDelegateForColumn()). Using WAbstractItemView#setEditOptions() you can customize if and how the view deals with multiple editors.
By default, all but the first columns are given a width of 150px, and the first column takes the remaining size. Note that this may have as consequence that the first column's size is reduced to 0. Column widths of all columns, including the first column, can be set through the API method setColumnWidth(), and also by the user using handles provided in the header.
Optionally, the treeview may be configured so that the first column is always visible while scrolling through the other columns, which may be convenient if you wish to display a model with many columns. Use setColumn1Fixed() to enable this behaviour.
If the model supports sorting (WAbstractItemModel#sort()), such as the WStandardItemModel, then you can enable sorting buttons in the header, using WAbstractItemView#setSortingEnabled().
You can allow selection on row or item level (using WAbstractItemView#setSelectionBehavior()), and selection of single or multiple items (using WAbstractItemView#setSelectionMode()), and listen for changes in the selection using the WAbstractItemView.selectionChanged() signal.
You may enable drag & drop support for this view, with awareness of the items in the model. When enabling dragging (see WAbstractItemView#setDragEnabled()), the current selection may be dragged, but only when all items in the selection indicate support for dragging (controlled by the ItemFlag.DragEnabled flag), and if the model indicates a mime-type (controlled by WAbstractItemModel.getMimeType()). Likewise, by enabling support for dropping (see WAbstractItemView#setDropsEnabled()), the treeview may receive a drop event on a particular item, at least if the item indicates support for drops (controlled by the ItemFlag.DropEnabled flag).
You may also react to mouse click events on any item, by connecting to one of the WAbstractItemView.clicked() or WAbstractItemView.doubleClicked() signals.

Graceful degradation

The view provides a virtual scrolling behavior which relies on Ajax availability. When Ajax is not available, a page navigation bar is used instead, see WAbstractItemView.getCreatePageNavigationBar(). In that case, the widget needs to be given an explicit height using resize() which determines the number of rows that are displayed at a time.
A snapshot of the WTreeView:

WTreeView example (default)

WTreeView example (polished)

Nested Class Summary
- Nested classes/interfaces inherited from class eu.webtoolkit.jwt.WObject
  WObject.FormData

Field Summary
- Fields inherited from class eu.webtoolkit.jwt.WAbstractItemView
  enabledDropLocations_, uDragWidget_
- Fields inherited from class eu.webtoolkit.jwt.WWidget
  WT_GETEXTRAMS_JS

Constructor Summary

Constructors
Constructor Description

WTreeView()
Creates a new tree view.

WTreeView(WContainerWidget parentContainer)
Creates a new tree view.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`collapse(WModelIndex index)`	Collapses a node.
`void`	`collapseAll()`	Collapse all expanded nodes.
`Signal1<WModelIndex>`	`collapsed()`	Signal emitted when a node is collapsed.
`protected void`	`enableAjax()`	Progresses to an Ajax-enabled widget.
`void`	`expand(WModelIndex index)`	Expands a node.
`Signal1<WModelIndex>`	`expanded()`	Signal emitted when a node is expanded.
`void`	`expandToDepth(int depth)`	Expands all nodes to a depth.
`int`	`getCurrentPage()`	Returns the current page.
`int`	`getPageCount()`	Returns the number of pages.
`int`	`getPageSize()`	Returns the page size.
`boolean`	`isExpanded(WModelIndex index)`	Returns whether a node is expanded.
`boolean`	`isRootDecorated()`	Returns whether toplevel items are decorated.
`WWidget`	`itemWidget(WModelIndex index)`	Returns the widget that renders an item.
`void`	`remove()`	Destructor.
`protected void`	`render(java.util.EnumSet<RenderFlag> flags)`	Renders the widget.
`void`	`resize(WLength width, WLength height)`	Resizes the widget.
`EventSignal1<WScrollEvent>`	`scrolled()`	Signal emitted when scrolling.
`void`	`scrollTo(WModelIndex index, ScrollHint hint)`	Scrolls the view to an item.
`void`	`setAlternatingRowColors(boolean enable)`	Sets if alternating row colors are to be used.
`void`	`setColumnHidden(int column, boolean hidden)`	Changes the visibility of a column.
`void`	`setColumnWidth(int column, WLength width)`	Sets the column width.
`void`	`setCurrentPage(int page)`	Sets the current page.
`void`	`setExpanded(WModelIndex index, boolean expanded)`	Expands or collapses a node.
`void`	`setHeaderHeight(WLength height)`	Sets the header height.
`void`	`setId(java.lang.String id)`	Sets the CSS Id.
`void`	`setModel(WAbstractItemModel model)`	Sets the model.
`void`	`setRootIsDecorated(boolean show)`	Sets whether toplevel items are decorated.
`void`	`setRowHeaderCount(int count)`	Configures the number of columns that are used as row headers.
`void`	`setRowHeight(WLength rowHeight)`	Sets the row height.

Methods inherited from class eu.webtoolkit.jwt.WAbstractItemView
clearSelection, clicked, closeEditor, closeEditor, closeEditors, closeEditors, columnResized, createExtraHeaderWidget, createHeaderWidget, doubleClicked, dropEvent, dropEvent, edit, extraHeaderWidget, getColumnAlignment, getColumnWidth, getCreatePageNavigationBar, getEditOptions, getEditTriggers, getEnabledDropLocations, getHeaderHeight, getHeaderItemDelegate, getItemDelegate, getItemDelegate, getItemDelegate, getItemDelegateForColumn, getModel, getRootIndex, getRowHeaderCount, getRowHeight, getSelectedIndexes, getSelectionBehavior, getSelectionMode, getSelectionModel, getSortColumn, getSortOrder, handleTouchEnd, handleTouchMove, handleTouchSelect, handleTouchStart, hasAlternatingRowColors, headerClicked, headerDoubleClicked, headerMouseWentDown, headerMouseWentUp, hideColumn, horizontalHeaderAlignment, isColumnHidden, isColumnResizeEnabled, isColumnResizeEnabled, isEditing, isSelected, isSortEnabled, isSortingEnabled, isSortingEnabled, isValid, keyPressed, keyWentDown, keyWentUp, modelHeaderDataChanged, mouseWentDown, mouseWentUp, pageChanged, scrollTo, select, select, selectionChanged, setColumnAlignment, setColumnResizeEnabled, setColumnResizeEnabled, setDragEnabled, setDropsEnabled, setEditOptions, setEditOptions, setEditTriggers, setEditTriggers, setEnabledDropLocations, setEnabledDropLocations, setHeaderAlignment, setHeaderAlignment, setHeaderClickSortEnabled, setHeaderItemDelegate, setHeaderWordWrap, setItemDelegate, setItemDelegateForColumn, setRootIndex, setSelectedIndexes, setSelectionBehavior, setSelectionMode, setSortingEnabled, setSortingEnabled, shiftEditorColumns, shiftEditorRows, showColumn, sortByColumn, touchEnded, touchMoved, touchStart, touchStarted, validateEditor, validateEditors, verticalHeaderAlignment

Methods inherited from class eu.webtoolkit.jwt.WCompositeWidget
addStyleClass, boxBorder, boxPadding, callJavaScriptMember, doJavaScript, find, findById, getAttributeValue, getBaseZIndex, getChildren, getClearSides, getDecorationStyle, getFloatSide, getHeight, getId, getImplementation, getJavaScriptMember, getLineHeight, getMargin, getMaximumHeight, getMaximumWidth, getMinimumHeight, getMinimumWidth, getObjectName, getOffset, getPositionScheme, getScrollVisibilityMargin, getStyleClass, getTabIndex, getTakeImplementation, getToolTip, getVerticalAlignment, getVerticalAlignmentLength, getWidth, hasFocus, hasStyleClass, isCanReceiveFocus, isDisabled, isEnabled, isHidden, isHiddenKeepsGeometry, isInline, isLoaded, isPopup, isScrollVisibilityEnabled, isScrollVisible, isSetFirstFocus, isThemeStyleEnabled, isVisible, load, propagateSetEnabled, propagateSetVisible, refresh, removeStyleClass, removeWidget, scrollVisibilityChanged, setAttributeValue, setCanReceiveFocus, setClearSides, setDecorationStyle, setDeferredToolTip, setDisabled, setFloatSide, setFocus, setHidden, setHiddenKeepsGeometry, setImplementation, setInline, setJavaScriptMember, setLineHeight, setMargin, setMaximumSize, setMinimumSize, setObjectName, setOffsets, setParentWidget, setPopup, setPositionScheme, setScrollVisibilityEnabled, setScrollVisibilityMargin, setSelectable, setStyleClass, setTabIndex, setThemeStyleEnabled, setToolTip, setVerticalAlignment

Methods inherited from class eu.webtoolkit.jwt.WWidget
acceptDrops, acceptDrops, addCssRule, addCssRule, addJSignal, addStyleClass, animateHide, animateShow, applyThemeStyles, createJavaScript, disable, dropEvent, enable, getDropTouch, getJsRef, getParent, hide, htmlText, isExposed, isGlobalWidget, isLayoutSizeAware, isRendered, layoutSizeChanged, needsRerender, positionAt, positionAt, positionAt, positionAt, removeFromParent, removeStyleClass, render, resize, scheduleRender, scheduleRender, scheduleRender, scheduleThemeStyleApply, setClearSides, setDeferredToolTip, setFocus, setHeight, setHidden, setLayoutSizeAware, setMargin, setMargin, setMargin, setMargin, setMargin, setOffsets, setOffsets, setOffsets, setOffsets, setOffsets, setToolTip, setVerticalAlignment, setWidth, show, stopAcceptDrops, toggleStyleClass, toggleStyleClass, tr

Methods inherited from class eu.webtoolkit.jwt.WObject
setFormData

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - WTreeView
```
public WTreeView(WContainerWidget parentContainer)
```
    Creates a new tree view.
  - WTreeView
```
public WTreeView()
```
    Creates a new tree view.
    Calls this((WContainerWidget)null)
- Method Detail
  - remove
```
public void remove()
```
    Description copied from class: WWidget
    
    Destructor.
    Deletes a widget and all contained contents.
    
    Overrides:
    
    remove in class WAbstractItemView
    
    See Also:
    
    WWidget.removeWidget(WWidget widget)
  - setExpanded
```
public void setExpanded(WModelIndex index,
                        boolean expanded)
```
    Expands or collapses a node.
    
    See Also:
    
    expand(WModelIndex index), collapse(WModelIndex index)
  - isExpanded
```
public boolean isExpanded(WModelIndex index)
```
    Returns whether a node is expanded.
    
    See Also:
    
    setExpanded(WModelIndex index, boolean expanded)
  - collapse
```
public void collapse(WModelIndex index)
```
    Collapses a node.
    
    See Also:
    
    setExpanded(WModelIndex index, boolean expanded), Note: until 3.3.4, selection was removed from within nodes that were collapsed. This (inconsistent) behavior has been removed in 3.3.4.
  - collapseAll
```
public void collapseAll()
```
    Collapse all expanded nodes.
    
    See Also:
    
    collapse(WModelIndex index), expand(WModelIndex index)
  - expand
```
public void expand(WModelIndex index)
```
    Expands a node.
    
    See Also:
    
    setExpanded(WModelIndex index, boolean expanded), collapse(WModelIndex index)
  - expandToDepth
```
public void expandToDepth(int depth)
```
    Expands all nodes to a depth.
    Expands all nodes to the given depth. A depth of 1 corresponds to the top level nodes.
    
    See Also:
    
    expand(WModelIndex index)
  - setRootIsDecorated
```
public void setRootIsDecorated(boolean show)
```
    Sets whether toplevel items are decorated.
    By default, top level nodes have expand/collapse and other lines to display their linkage and offspring, like any node.
    By setting show to false, you can hide these decorations for root nodes, and in this way mimic a plain list. You could also consider using a WTableView instead.
  - isRootDecorated
```
public boolean isRootDecorated()
```
    Returns whether toplevel items are decorated.
    
    See Also:
    
    setRootIsDecorated(boolean show)
  - resize
```
public void resize(WLength width,
                   WLength height)
```
    Description copied from class: WWidget
    Resizes the widget.
    Specifies a fixed size for this widget, setting CSS width and height properties. By default a widget has automatic width and height, which sets a size for the widget following CSS rules.
    When the widget is not managed by a layout manager, the automatic (natural) size of a widget depends on whether the widget is a block or inline widget:
    
    a block widget takes by default the width of the parent, and the height that it needs based on its contents
    an inline widget takes the width and height that it needs based on its contents (possibly wrapping over multiple lines). The width and height of an inline widget cannot be changed (by the letter of CSS, although most browsers will react to it in varying ways).
    
    When inserted in a layout manager, the size set will be used as a widget's preferred size, but the widget may be given a different size by the layout manager based on available space and stretch factors. The actual size given by a layout manager may be retrieved by making the widget "layout size aware", using setLayoutSizeAware(). If you have defined a "wtResize()" JavaScript method for the widget, then this method will also be called.
    The default width and height of a widget is WLength.Auto.
    Overrides:
    
    resize in class WCompositeWidget
    
    See Also:
    
    WWidget.getWidth(), WWidget.getHeight()
  - collapsed
```
public Signal1<WModelIndex> collapsed()
```
    Signal emitted when a node is collapsed.
    
    See Also:
    
    setExpanded(WModelIndex index, boolean expanded), expanded()
  - expanded
```
public Signal1<WModelIndex> expanded()
```
    Signal emitted when a node is expanded.
    
    See Also:
    
    setExpanded(WModelIndex index, boolean expanded), collapsed()
  - itemWidget
```
public WWidget itemWidget(WModelIndex index)
```
    Description copied from class: WAbstractItemView
    
    Returns the widget that renders an item.
    This returns the widget that renders the given item. This may return 0 if the item is currently not rendered.
    This widget has been created by an item delegate, and usually an item delegate is involved when updating it.
    
    Specified by:
    
    itemWidget in class WAbstractItemView
  - setModel
```
public void setModel(WAbstractItemModel model)
```
    Description copied from class: WAbstractItemView
    
    Sets the model.
    The View will display data of the given model and changes in the model are reflected by the View.
    The initial model is null.
    
    Overrides:
    
    setModel in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.setRootIndex(WModelIndex rootIndex)
  - setColumnWidth
```
public void setColumnWidth(int column,
                           WLength width)
```
    Sets the column width.
    For a model with WAbstractItemModel#getColumnCount() == N, the initial width of columns 1..N is set to 150 pixels, and column 0 will take all remaining space.
    
    Note: The actual space occupied by each column is the column width augmented by 7 pixels for internal padding and a border.
    
    Specified by:
    
    setColumnWidth in class WAbstractItemView
    
    See Also:
    
    setRowHeight(WLength rowHeight)
  - setAlternatingRowColors
```
public void setAlternatingRowColors(boolean enable)
```
    Description copied from class: WAbstractItemView
    
    Sets if alternating row colors are to be used.
    Configure whether rows get alternating background colors, defined by the current CSS theme.
    The default value is false.
    
    Overrides:
    
    setAlternatingRowColors in class WAbstractItemView
  - setRowHeight
```
public void setRowHeight(WLength rowHeight)
```
    Description copied from class: WAbstractItemView
    
    Sets the row height.
    The view renders all rows with a same height. This method configures this row height.
    The default value is 20 pixels.
    
    Note: The height must be specified in LengthUnit.Pixel units.
    
    Overrides:
    
    setRowHeight in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.setColumnWidth(int column, WLength width)
  - setHeaderHeight
```
public void setHeaderHeight(WLength height)
```
    Description copied from class: WAbstractItemView
    
    Sets the header height.
    The default value is 20 pixels.
    
    Note: The height must be specified in LengthUnit.Pixel units.
    
    Overrides:
    
    setHeaderHeight in class WAbstractItemView
  - setColumnHidden
```
public void setColumnHidden(int column,
                            boolean hidden)
```
    Description copied from class: WAbstractItemView
    
    Changes the visibility of a column.
    
    Overrides:
    
    setColumnHidden in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.isColumnHidden(int column)
  - setRowHeaderCount
```
public void setRowHeaderCount(int count)
```
    Description copied from class: WAbstractItemView
    
    Configures the number of columns that are used as row headers.
    An item view does not use the vertical header data from the model in any way, but instead you can configure data in the first column(s) to be used as a row headers.
    These columns will not scroll horizontally together with the rest of the model.
    The default value is 0.
    
    Note: Currently, this property must be set before any other settings of the view and only a value of 0 or 1 is supported.
    
    Overrides:
    
    setRowHeaderCount in class WAbstractItemView
  - getPageCount
```
public int getPageCount()
```
    Description copied from class: WAbstractItemView
    
    Returns the number of pages.
    When Ajax/JavaScript is not available, the view will use a paging navigation bar to allow scrolling through the data. This returns the number of pages currently shown.
    
    Specified by:
    
    getPageCount in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.getCreatePageNavigationBar(), WAbstractItemView.pageChanged()
  - getPageSize
```
public int getPageSize()
```
    Description copied from class: WAbstractItemView
    
    Returns the page size.
    When Ajax/JavaScript is not available, the view will use a paging navigation bar to allow scrolling through the data. This returns the number of items per page.
    
    Specified by:
    
    getPageSize in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.getCreatePageNavigationBar(), WAbstractItemView.pageChanged()
  - getCurrentPage
```
public int getCurrentPage()
```
    Description copied from class: WAbstractItemView
    
    Returns the current page.
    When Ajax/JavaScript is not available, the view will use a paging navigation bar to allow scrolling through the data. This returns the current page (between 0 and getPageCount() - 1).
    
    Specified by:
    
    getCurrentPage in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.getCreatePageNavigationBar(), WAbstractItemView.pageChanged()
  - setCurrentPage
```
public void setCurrentPage(int page)
```
    Description copied from class: WAbstractItemView
    
    Sets the current page.
    When Ajax/JavaScript is not available, the view will use a paging navigation bar to allow scrolling through the data. This method can be used to change the current page.
    
    Specified by:
    
    setCurrentPage in class WAbstractItemView
    
    See Also:
    
    WAbstractItemView.getCreatePageNavigationBar(), WAbstractItemView.pageChanged()
  - scrollTo
```
public void scrollTo(WModelIndex index,
                     ScrollHint hint)
```
    Description copied from class: WAbstractItemView
    
    Scrolls the view to an item.
    Scrolls the view to ensure that the item which represents the provided index is visible. A hint may indicate how the item should appear in the viewport (if possible).
    
    Note: Currently only implemented to scroll to the correct row, not taking into account the column.
    
    Specified by:
    
    scrollTo in class WAbstractItemView
  - scrolled
```
public EventSignal1<WScrollEvent> scrolled()
```
    Description copied from class: WAbstractItemView
    
    Signal emitted when scrolling.
    
    Note: Works only if ajax is available.
    
    Specified by:
    
    scrolled in class WAbstractItemView
  - setId
```
public void setId(java.lang.String id)
```
    Description copied from class: WWidget
    
    Sets the CSS Id.
    Sets a custom Id. Note that the Id must be unique across the whole widget tree, can only be set right after construction and cannot be changed. This is mostly useful for in tests using a test plan that manipulates DOM elements by Id.
    By default, auto-generated id's are used.
    
    Note: An id must start with a letter ([A-Za-z]), followed by one or more letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").
    Warning: We recommend that you leave the id of a widget unchanged. JWt uses the id to identify widgets in the JavaScript it generates, and this can often leads to bugs. If you do change the id, only change the id right after widget construction. However, usually there's a more preferable alternative, like setting the object name (WObject#setObjectName()), or adding style classes (addStyleClass()).
    
    Overrides:
    
    setId in class WCompositeWidget
    
    See Also:
    
    WObject.getId()
  - render
```
protected void render(java.util.EnumSet<RenderFlag> flags)
```
    Description copied from class: WWidget
    
    Renders the widget.
    This function renders the widget (or an update for the widget), after this has been scheduled using scheduleRender().
    The default implementation will render the widget by serializing changes to JavaScript and HTML. You may want to reimplement this widget if you have been postponing some of the layout / rendering implementation until the latest moment possible. In that case you should make sure you call the base implementation however.
    
    Overrides:
    
    render in class WCompositeWidget
  - enableAjax
```
protected void enableAjax()
```
    Description copied from class: WWidget
    
    Progresses to an Ajax-enabled widget.
    This method is called when the progressive bootstrap method is used, and support for AJAX has been detected. The default behavior will upgrade the widget's event handling to use AJAX instead of full page reloads, and propagate the call to its children.
    You may want to reimplement this method if you want to make changes to widget when AJAX is enabled. You should always call the base implementation.
    
    Overrides:
    
    enableAjax in class WAbstractItemView
    
    See Also:
    
    WApplication.enableAjax()

Constructor	Description
`WTreeView()`	Creates a new tree view.
`WTreeView(WContainerWidget parentContainer)`	Creates a new tree view.

Class WTreeView

Graceful degradation

Nested Class Summary

Nested classes/interfaces inherited from class eu.webtoolkit.jwt.WObject

Field Summary

Fields inherited from class eu.webtoolkit.jwt.WAbstractItemView

Fields inherited from class eu.webtoolkit.jwt.WWidget

Constructor Summary

Method Summary

Methods inherited from class eu.webtoolkit.jwt.WAbstractItemView

Methods inherited from class eu.webtoolkit.jwt.WCompositeWidget

Methods inherited from class eu.webtoolkit.jwt.WWidget

Methods inherited from class eu.webtoolkit.jwt.WObject

Methods inherited from class java.lang.Object

Constructor Detail

WTreeView

WTreeView

Method Detail

remove

setExpanded

isExpanded

collapse

collapseAll

expand

expandToDepth

setRootIsDecorated

isRootDecorated

resize

collapsed

expanded

itemWidget

setModel

setColumnWidth

setAlternatingRowColors

setRowHeight

setHeaderHeight

setColumnHidden

setRowHeaderCount

getPageCount

getPageSize

getCurrentPage

setCurrentPage

scrollTo

scrolled

setId

render

enableAjax