![]() ![]() Which property to use as a source for child items of the node. Instead, we use the HierarchicalDataTemplate, which allows us to template both the tree node itself, while controlling The WPF TreeView supports data binding, like pretty much all other WPF controls does, but because the TreeView is hierarchical in nature, a normalĭataTemplate often won't suffice. If CheckBoxes is set to true again, the first and second images of the StateImageList are shown to indicate a checked or unchecked state, respectively.The TreeView control: TreeView, data binding and multiple templates In this case, the state image at the indicated index position is shown. However, the displayed images may be different if the following situation occurs: If the SelectedImageIndex of the node is set to a value other than 0 or 1, and the CheckBoxes property of the parent TreeView is set to false, the SelectedImageIndex will not automatically reset to -1 to indicate it is not set. When the CheckBoxes property of a TreeView is set to true, and the StateImageList property is set, each TreeNode that is contained in the TreeView displays the first and second images from the StateImageList to indicate an unchecked or checked state, respectively. Check boxes allow the user to select more than one tree node at a time. ' Recursively check the children of the current child node.Ī check box is displayed to the left of both the tree node label and tree node Image, if any. Private Function HasCheckedChildNodes(ByVal node As TreeNode) As Boolean ![]() ![]() ' Returns a value indicating whether the specified Private Sub CheckForCheckedChildren(ByVal sender As Object, ByVal e As TreeViewCancelEventArgs) ' Prevent expansion of a node that does not have any checked child nodes. RemoveHandler treeView1.BeforeExpand, AddressOf CheckForCheckedChildren ' event so manual node expansion will work correctly. ' Remove the checkForCheckedChildren event handler from the BeforeExpand ' prevented from expanding by the checkForCheckedChildren event handler. ' Add the CheckForCheckedChildren event handler to the BeforeExpand event.ĪddHandler treeView1.BeforeExpand, AddressOf CheckForCheckedChildren ' Disable redrawing of treeView1 to prevent flickering Private Sub showCheckedNodesButton_Click(ByVal sender As Object, ByVal e As EventArgs) TreeView1.Anchor = AnchorStyles.Top | AnchorStyles.Left |ĪnchorStyles.Bottom | AnchorStyles.Right New TreeViewCancelEventHandler(CheckForCheckedChildrenHandler) Private TreeViewCancelEventHandler checkForCheckedChildren Recursively check the children of the current child node. TreeNode^ childNode = safe_cast(myEnum->Current) System::Collections::IEnumerator^ myEnum = node->Nodes->GetEnumerator() Returns a value indicating whether the specifiedīool HasCheckedChildNodes( TreeNode^ node ) Void CheckForCheckedChildrenHandler( Object^ /*sender*/, TreeViewCancelEventArgs^ e ) Prevent expansion of a node that does not have any checked child nodes. TreeView1->BeforeExpand -= checkForCheckedChildren event so manual node expansion will work correctly. Remove the checkForCheckedChildren event handler from the BeforeExpand prevented from expanding by the checkForCheckedChildren event handler. TreeView1->BeforeExpand += checkForCheckedChildren Add the checkForCheckedChildren event handler to the BeforeExpand event. Disable redrawing of treeView1 to prevent flickering Void showCheckedNodesButton_Click( Object^ /*sender*/, EventArgs^ /*e*/ ) TreeView1->Anchor = static_cast(AnchorStyles::Top | AnchorStyles::Left | AnchorStyles::Bottom | AnchorStyles::Right) įor ( int x = 0 x Nodes->Add( String::Format( "Node TreeViewCancelEventHandler^ checkForCheckedChildren ĬheckForCheckedChildren = gcnew TreeViewCancelEventHandler( this, &Form1::CheckForCheckedChildrenHandler ) This behavior can also be implemented by handling the BeforeCollapse event, as illustrated in the example for that topic. In order to allow standard node expansion when the plus sign next to a node is clicked, the BeforeExpand event handler is then removed. If a node does not have checked children, the expansion is canceled for that node. The BeforeExpand event handler determines whether a given node has child nodes that are checked. First, all the nodes are collapsed, and a handler is added for the BeforeExpand event. The following code example demonstrates how to change the collapse state of a TreeView so that all the checked nodes are visible. True if a check box is displayed next to each tree node in the tree view control otherwise, false. ![]()
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