A single node in a tree. More...
#include <Wt/WTreeNode>
Public Types | |
enum | LoadPolicy { LazyLoading, PreLoading, NextLevelLoading } |
An enumeration for the policy to load children. More... | |
enum | ChildCountPolicy { Disabled, Enabled, Lazy } |
An enumeration for the policy to display the child count. More... | |
Public Member Functions | |
WTreeNode (const WString &labelText, WIconPair *labelIcon=0, WTreeNode *parentNode=0) | |
Creates a tree node with the given label. | |
~WTreeNode () | |
Destructor. | |
WText * | label () const |
Returns the label. | |
WIconPair * | labelIcon () const |
Returns the label icon. | |
void | setLabelIcon (WIconPair *labelIcon) |
Sets the label icon. | |
virtual void | addChildNode (WTreeNode *node) |
Adds a child node. | |
void | removeChildNode (WTreeNode *node) |
Removes a child node. | |
const std::vector< WTreeNode * > & | childNodes () const |
Returns the list of children. | |
virtual int | displayedChildCount () const |
Returns the number of children that should be displayed. | |
void | setChildCountPolicy (ChildCountPolicy policy) |
Configures how and when the child count should be displayed. | |
ChildCountPolicy | childCountPolicy () const |
Returns the child count policy. | |
void | setImagePack (const std::string &url) |
Sets the image pack for this (sub)tree (deprecated). | |
void | setLoadPolicy (LoadPolicy loadPolicy) |
Sets the load policy for this tree. | |
bool | isExpanded () const |
Returns whether this node is expanded. | |
void | setSelectable (bool selectable) |
Allows this node to be selected. | |
virtual bool | isSelectable () const |
Returns if this node may be selected. | |
WTreeNode * | parentNode () const |
Returns the parent node. | |
void | setNodeVisible (bool visible) |
Sets the visibility of the node itself. | |
void | expand () |
Expands this node. | |
void | collapse () |
Collapses this node. | |
EventSignal< WMouseEvent > & | expanded () |
Signal emitted when the node is expanded by the user. | |
EventSignal< WMouseEvent > & | collapsed () |
Signal emitted when the node is collapsed by the user. | |
Signal< bool > & | selected () |
Signal that is emitted when the node is added or removed from the selection | |
Protected Member Functions | |
WTreeNode (WTreeNode *parentNode=0) | |
Creates a tree node with empty labelArea(). | |
WTableCell * | labelArea () |
Accesses the container widget that holds the label area. | |
virtual void | populate () |
Populates the node dynamically on loading. | |
bool | populated () const |
Returns whether this node has already been populated. | |
virtual bool | expandable () |
Returns whether this node can be expanded. | |
virtual void | renderSelected (bool selected) |
Renders the node to be selected. | |
std::string | imagePack () const |
The image pack that is used for this tree node (deprecated). | |
virtual void | descendantRemoved (WTreeNode *node) |
Reacts to the removal of a descendant node. | |
virtual void | descendantAdded (WTreeNode *node) |
Reacts to the addition of a descendant node. | |
virtual void | doExpand () |
The actual expand. | |
virtual void | doCollapse () |
The actual collapse. | |
virtual void | undoDoExpand () |
Undo method for doCollapse() stateless implementation. | |
virtual void | undoDoCollapse () |
Undo method for doCollapse() stateless implementation. |
A single node in a tree.
A tree list is constructed by combining several tree node objects in a tree hierarchy, by passing the parent tree node as the last argument in the child node constructor, or by using addChildNode(), to add a child to its parent.
Each tree node has a label, and optionally a label icon pair. The icon pair offers the capability to show a different icon depending on the state of the node (expanded or collapsed). When the node has any children, a child count may be displayed next to the label using setChildCountPolicy().
Expanding a tree node it will collapse all its children, so that a user may collapse/expand a node as a short-cut to collapsing all children.
The treenode provides several policies to communicate the current contents of the tree to the client (if possible):
The default policy is WTreeNode::LazyLoading. Another load policy may be specified using setLoadPolicy() on the root node and before adding any children. The load policy is inherited by all children in the tree.
There are a few scenarios where it makes sense to specialize the WTreeNode class. One scenario is create a tree that is populated dynamically while browsing. For this purpose you should reimplement the populate() method, whose default implementation does nothing. This method is called when 'loading' the node. The exact moment for loading a treenode depends on the LoadPolicy.
A second scenario that is if you want to customize the look of the tree label (see labelArea()) or if you want to modify or augment the event collapse/expand event handling (see doExpand() and doCollapse()).
See WTree for a usage example.
The tree is styled by the current CSS theme. The look can be overridden using the Wt-tree
CSS class and the following selectors:
.Wt-tree .Wt-trunk : vertical line, trunk .Wt-tree .Wt-end : vertical line, last item .Wt-tree .Wt-collapse : collapse icon (img *) .Wt-tree .Wt-expand : expand icon (img *) .Wt-tree .Wt-noexpand : leaf icon .Wt-tree .Wt-label : the node label .Wt-tree .Wt-childcount : the node child count
* The collapse and expand icons are fetched themselves as images, nav-plus.gif
and nav-minus.gif
.
Wt::WTreeNode::WTreeNode | ( | const WString & | labelText, |
WIconPair * | labelIcon = 0 , |
||
WTreeNode * | parentNode = 0 |
||
) |
Creates a tree node with the given label.
The labelIcon, if specified, will appear just before the label and its state reflect the expand/collapse state of the node.
The node is initialized to be collapsed.
Wt::WTreeNode::WTreeNode | ( | WTreeNode * | parentNode = 0 ) |
[protected] |
Creates a tree node with empty labelArea().
This tree node has no label or labelicon, and is therefore ideally suited to provide a custom look.
ChildCountPolicy Wt::WTreeNode::childCountPolicy | ( | ) | const [inline] |
Returns the child count policy.
void Wt::WTreeNode::collapse | ( | ) |
Collapses this node.
EventSignal< WMouseEvent > & Wt::WTreeNode::collapsed | ( | ) |
Signal emitted when the node is collapsed by the user.
void Wt::WTreeNode::descendantAdded | ( | WTreeNode * | node ) | [protected, virtual] |
Reacts to the addition of a descendant node.
Reimplement this method if you wish to react on the addition of a descendant node. The default implementation simply propagates the event to the parent.
void Wt::WTreeNode::descendantRemoved | ( | WTreeNode * | node ) | [protected, virtual] |
Reacts to the removal of a descendant node.
Reimplement this method if you wish to react on the removal of a descendant node. The default implementation simply propagates the event to the parent.
int Wt::WTreeNode::displayedChildCount | ( | ) | const [virtual] |
Returns the number of children that should be displayed.
This is used to display the count in the count label. The default implementation simply returns childNodes().size().
void Wt::WTreeNode::doCollapse | ( | ) | [protected, virtual] |
The actual collapse.
This method, which is implemented as a stateless slot, performs the actual collapse of the node.
You may want to reimplement this function (and undoDoCollapse()) if you wish to do additional things on node expansion.
void Wt::WTreeNode::doExpand | ( | ) | [protected, virtual] |
The actual expand.
This method, which is implemented as a stateless slot, performs the actual expansion of the node.
You may want to reimplement this function (and undoDoExpand()) if you wish to do additional things on node expansion.
void Wt::WTreeNode::expand | ( | ) |
Expands this node.
Besides the actual expansion of the node, this may also trigger the loading and population of the node children, or of the children's children.
bool Wt::WTreeNode::expandable | ( | ) | [protected, virtual] |
Returns whether this node can be expanded.
The default implementation populates the node if necessary, and then checks if there are any child nodes.
You may wish to reimplement this method if you reimplement populate(), and you have a quick default for determining whether a node may be expanded (which does not require populating the node).
EventSignal< WMouseEvent > & Wt::WTreeNode::expanded | ( | ) |
Signal emitted when the node is expanded by the user.
std::string Wt::WTreeNode::imagePack | ( | ) | const [protected] |
The image pack that is used for this tree node (deprecated).
virtual bool Wt::WTreeNode::isSelectable | ( | ) | const [inline, virtual] |
Returns if this node may be selected.
WTableCell * Wt::WTreeNode::labelArea | ( | ) | [protected] |
Accesses the container widget that holds the label area.
Use this to customize how the label should look like.
WTreeNode * Wt::WTreeNode::parentNode | ( | ) | const |
Returns the parent node.
void Wt::WTreeNode::populate | ( | ) | [protected, virtual] |
Populates the node dynamically on loading.
Reimplement this method if you want to populate the widget dynamically, as the tree is being browsed and therefore loaded. This is only usefull with LazyLoading or NextLevelLoading strategies.
bool Wt::WTreeNode::populated | ( | ) | const [inline, protected] |
Returns whether this node has already been populated.
void Wt::WTreeNode::renderSelected | ( | bool | selected ) | [protected, virtual] |
Renders the node to be selected.
The default implementation changes the style class of the labelArea() to "selected".
Signal<bool>& Wt::WTreeNode::selected | ( | ) | [inline] |
Signal that is emitted when the node is added or removed from the selection
void Wt::WTreeNode::setChildCountPolicy | ( | ChildCountPolicy | policy ) |
Configures how and when the child count should be displayed.
By default, no child count indication is disabled (this is the behaviour since 2.1.1). Use this method to enable child count indications.
The child count policy is inherited by all children in the tree.
void Wt::WTreeNode::setImagePack | ( | const std::string & | url ) |
Sets the image pack for this (sub)tree (deprecated).
void Wt::WTreeNode::setLoadPolicy | ( | LoadPolicy | loadPolicy ) |
Sets the load policy for this tree.
This may only be set on the root of a tree, and before adding any children.
void Wt::WTreeNode::setNodeVisible | ( | bool | visible ) |
Sets the visibility of the node itself.
If false
, then the node itself is not displayed, but only its children. This is typically used to hide the root node of a tree.
void Wt::WTreeNode::setSelectable | ( | bool | selectable ) | [virtual] |
Allows this node to be selected.
By default, all nodes may be selected.
Reimplemented from Wt::WCompositeWidget.
void Wt::WTreeNode::undoDoCollapse | ( | ) | [protected, virtual] |
Undo method for doCollapse() stateless implementation.
void Wt::WTreeNode::undoDoExpand | ( | ) | [protected, virtual] |
Undo method for doCollapse() stateless implementation.