Hi Mohni,

I’ve constructed and attached a sample specifically demonstrating the behavior that you are interested in.

Please let me know if you have any questions regarding this approach or if you have any further questions that I may assist you with.

Warm regards,

Chris

Thank you for the sample Chris! This is definitely a step in the direction of what I want. If I wan to handle three-state checkbox, which function will I have to modify and what is the property I have to check? In my object structure, if I make IsChecked property as nullable(of Boolean) will that automatically handle three state checkbox or I have to make modifications in XAML also?

Thanks

Hi Mohni,

You are certainly welcome! As this implementation uses the built-in WPF Checkbox, you will need to use its IsThreeState property, setting it to ‘True’.

The best place to enable this behavior, in this case is within your ItemTemplate, where you’ve defined your NodeLayouts, as in the following code snippet.

<igDT:NodeLayout.ItemTemplate>
    <DataTemplate>
        <StackPanel Orientation="Horizontal">
           <CheckBox IsThreeState="True"
             Checked="CheckBox_Checked"
             Unchecked="CheckBox_Checked"
             IsChecked="{Binding Path=Node.Data.IsChecked}"/>
           <TextBlock Text="{Binding Path=Node.Data.Name}"  Margin="5, 0, 0, 0"/>
        </StackPanel>
    </DataTemplate>
</igDT:NodeLayout.ItemTemplate>

Next, you will need to set the type for your IsChecked property off of the Node class to a nullable type, such as ‘bool?’; this will allow you to manage an intermediate state for your checkboxes, by getting/setting that checkboxes IsChecked property to null.

Bear in mind, however that since you need to manual define the behavior used for checkbox interactions between nodes for your requirement, that this behavior too will need to be accounted for in your approach.

Please let me know if you have any further questions that I may assist you with.

Warm regards,
Chris K.

Hi Chris,

   I tried it like this and it works to an extent. I found only one problem: If I click repeatedly on the checkbox of a child node, it turns into "True", then "Indeterminate" and then "False". Is there a way to handle the indeterminate state if the node does not have any children? So if some parent node has 3 children, but only 1 is checked, then I understand it can show "Indeterminate" state, but how to handle to child node?

What I mean, can I have three state checkbox for parent nodes, but  two states for the lowest level child nodes?

Also, is there a checkbox click event on XamDataTree? Is it possible to make the DataTemplate checkbox look like XamDataTree checkbox? What style I can use for this?

Thanks,

Hi Mohni,

The behavior of managing the CheckBox type for your templated Node checkboxes based on the presence of child nodes is possible by binding the IsThreeState property on your CheckBox template to a converter that will then return the value of the HasChildren property off of the associated node’s DataContext.

The XamDataTree does not have an event associated with clicking on or changing the checked state of its checkboxes; there is however, an IsChecked property exposed from XamDataTreeNode that may be used in conjunction with the INotifyPropertyChanged interface to monitor the checked state for nodes.

In this particular scenario, since the XamDataTree’s checkboxes aren’t used anyway, you could take advantage of the built-in WPF checkbox’s click event, (via the template Checkbox in  NodeLayouts.ItemTemplate) for whatever behavior you had in mind.

As for styling the WPF checkboxes to match the style for those used by the XamDataTree, you will be able to reuse its default style, (which you’ve already defined in your sample as “cbstyle”) that can be set as the style for the template checkboxes within the NodeLayouts.ItemTemplate.

I’ve modified our earlier sample to include these changes as well as the following code snippet for further context.

<!--XAML for the XamDataTree-->
<igDT:XamDataTree Name="OtherTree">
     <igDT:XamDataTree.Resources>
          <local:ThreeStateConverter x:Key="ThreeStateConverter"/>
     </igDT:XamDataTree.Resources>
 
 <igDT:XamDataTree.GlobalNodeLayouts>
     <igDT:NodeLayout Key="NodeLayout"
         TargetTypeName="Node"
         DisplayMemberPath="Name">
   <igDT:NodeLayout.ItemTemplate>
    <DataTemplate>
     <StackPanel Orientation="Horizontal">
         <CheckBox Checked="CheckBox_Checked"
           Unchecked="CheckBox_Checked"
           IsChecked="{Binding Path=Node.Data.IsChecked}"
           IsThreeState="{ Binding Converter=
           {StaticResource ThreeStateConverter}}"/>
           Style="{StaticResource cbstyle}"
         <TextBlock Text="{Binding Path=Node.Data.Name}" 
           Margin="5, 0, 0, 0"/>
     </StackPanel>
    </DataTemplate>
   </igDT:NodeLayout.ItemTemplate>
  </igDT:NodeLayout>
 </igDT:XamDataTree.GlobalNodeLayouts>
</igDT:XamDataTree>

//Value Converter
public class ThreeStateConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
         XamDataTreeNodeDataContext nodeContext = value as XamDataTreeNodeDataContext;

         return nodeContext.Node.HasChildren;
 }

 public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
 {
     return new NotImplementedException();
 }
}

Please let me know if you have any further questions.

Warm regards,

Chris K.

Thanks a lot Chris! that works!

I have another question. this is inside a normal XamDataTree with checkBox mode = auto.

When the TreeNodeCheckChanged fires, is it possible to cancel the event if a certain condition is not met? So if a node got checked (childNode) because another node is checked (parentNode), but I don't want this node (childNode) to be checked (maybe other child nodes can be checked or not), how can I cancel the changing of the node?

If I cancel, will it again fire the event for all the related nodes, if I have check box mode = auto?

Thanks,

Hi Mohni,

Your certainly welcome! The XamDataTree doesn’t support user customizable conditional checkbox selection, (out of the box anyway) aside from what’s handled for you when it’s CheckBoxMode is set to ‘Auto’; this would make an interesting product idea.

Further, the XamDataTree’s NodeCheckChanged event doesn’t expose a cancelation argument, but it is possible to achieve both a conditional check behavior, (which you will need to handle, yourself) as well as a pseudo checked cancellation for nodes.

As an example, say you have several sibling nodes belonging to some parent node and you only want one of those nodes to be checked at any given time, (effectively wanting to cancel the checked state for any of its sibling nodes, should the condition arise that they might also enter a checked condition); you could hook into the NodeCheckedChanged event of the XamDataTree, check if your node in question is ‘potentially’ being changed to a checked state and if so, then iterate thru its sibling nodes to first verify that they are not also checked, if at least one is checked, then return false, otherwise return true and allow that node to become checked.

With the CheckboxMode set to ‘Auto’ on the XamDataTree, child nodes of the parent node which has had its checked event ‘cancelled’ will behave as if it’s parent was never checked at all; however, they themselves will remain checkable.

I’ve constructed and attached a sample that demonstrates this approach for further context and I’ve limited the scope of nodes to be checked to those of ‘Type.C’, from our previous sample as you might want some way of limiting this behavior to a particular set of nodes.

Please let me know if you have any further questions.

P.S. If you do have any new questions, please create a new thread for it, (as this one may become difficult for other IG community members to follow, as it encompasses several different issues) and include the link to that thread in your response here and I, (if I can) or one of my team mates will assist you on that new thread.

Warm regards,

Chris