A class for adding "standard" hierarchical selection behavior to your CheckboxTreeViewer
We've all seen this in numerous applications: checking a node in a checkbox tree widget selects all descendants and grays out all ancestors. Similarly, unchecking a node recursively executes the same logic in reverse. As a familiar example, the Resource Working Set dialog comes to mind (org.eclipse.ui.internal.dialogs.ResourceWorkingSetPage):
In fact, this behavior is so commonplace that if you've never used the JFace CheckboxTreeViewer class before, you might expect it to implement this behavior by default. However, this is not the case.
After reimplementing this behavior repeatedly in my applications, I finally made a simple helper class to make this process easier. To add this behavior to your CheckboxTreeViewer, simply add the following code, before setting the viewer input:
CheckboxTreeSelectionHelper.attach(checkboxTreeViewer,myContentProvider);Make sure your content provider implements getParent(), otherwise ancestor updates won't work correctly.
I've
attached the helper class along with a complete example application.
Hopefully this will make it easier for you to implement this
commonplace checkbox tree behavior in your applications.
A word of
caution: this code is provided as-is and has not undergone extensive
testing. Please post any bug fixes or enhancements here.
Example app: CheckboxTreeSelectionHelperTestDialog.java
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Comments
Ash Mughal replied on Fri, 2011/12/23 - 1:59pm
Hi Zac,
Very nice article on "A class for adding "standard" hierarchical selection behavior to your CheckboxTreeViewer".
It was really helpful to understand basics of CheckboxTreeViewer.
Also can you please share your experiences in rendering of these check boxes?
Zac Wolfe replied on Fri, 2011/12/23 - 4:10pm
in response to:
Ash Mughal
Thanks for the comment Ash. Actually the rendering of the checkboxes is handled by the CheckboxTreeViewer, or more specifically, by the underlying SWT Tree type.
I think you might find the example application helpful (CheckboxTreeSelectionHelperTestDialog.java) as it demonstrates some CheckboxTreeViewer basics as well as how to use the helper class.