Description Saurabh Bagrodia 2004-04-19 16:00:57 EDT

Currently in the Eclipse JFace Tree Viewer infrastructure we have a method 
called getVisibleExpandedElements that returns all the visible "and" expanded 
object in the view. What I wanted was a method that returned all the visible 
objects (whether expanded or not)

I am not sure if the intention of the getVisibleExpandedElements method was 
getting all visible elements or not but I think this is a much more important 
behaviour from the UI point-of-view.. For example in my case I have 2 label 
providers for my tree view and I need to switch between them from time to time 
and to do the switch in a more optimized manner I need to get the visible 
objects and call update on them instead of calling refresh on the entire view 
which is very expensive execution wise.

I had implemented the method and am pasting it below: 

	public Object[] getVisibleElements(){	
		ArrayList visibleElements = new ArrayList();
		recursiveGetVisibleElements(visibleElements,getTree());
		return visibleElements.toArray();
	}


	/**
	 * @param tree
	 * @return
	 */
	private void recursiveGetVisibleElements(ArrayList visibleElements, 
Widget item) {	
		
		if (!(item instanceof Item) || getExpanded((Item)item)) {
			
			Item[] children = getChildren(item);
			
			for (int i = 0; i < children.length; i++) {
				
				Item child = children[i];
				
				Object data = child.getData();
				if (data != null)
					visibleElements.add(data);	
			
				
				recursiveGetVisibleElements(visibleElements, 
child);
			}
		}		
		
	}


Its very similar to the getVisibleExpandedElements method, the difference 
being here I am checking if the passed object is expanded and if its I add its 
children to the resulting list and then recurse on the children whereas in the 
getVisibleExpandedElements method first the children of the passed element are 
obtained and then the children are checked to see whether they are expended 
and if they are then they are added to the resulting list and the method is 
recursed on them.

Thanks!