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View Full Version : Tree Object: go to Previous Leaf



Stooshie
12-18-2008, 01:58 PM
Hi there.

I have written a walkNext() method which goes to the next leaf in the tree:



private function walkNext(_tree:Tree, _count:int=0):void
{
_count++;
if((_count <= 1))
{
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
_tree.expandItem(_tree.selectedItem,true,true);
_tree.validateNow();
}
}
_tree.selectedIndex++;
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
_tree.expandItem(_tree.selectedItem,true,true);
_tree.validateNow();
// recursion --->
walkNext(_tree,_count);
}
// else if a leaf
else
{
// scroll to the selected index
_tree.scrollToIndex(_tree.selectedIndex);
_tree.validateNow();
// finished ---|
}
}


I am trying to write a walkPrevious() which goes to the previous leaf, like this:


private function walkPrevious(_tree:Tree, _count:int=0):void
{
_count++;
if(_tree.selectedIndex > 0)
{
_tree.selectedIndex--;
_tree.validateNow();
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
if(_tree.isItemOpen(_tree.selectedItem))
{
walkPrevious(_tree,_count);
// recursion --->
}
// if branch is closed
else
{
_tree.expandItem(_tree.selectedItem,true,true);
// go forward to original selection (doesn't go into the sub branch as tree not validated yet)
_tree.selectedIndex++;
_tree.validateNow();
// now go back one
walkPrevious(_tree,_count);
// recursion --->
}
}
// if not a branch
else
{
_tree.scrollToIndex(_tree.selectedIndex);
_tree.validateNow();
// finished ---|
}
}
// if selected index <= 0
else
{
myTree.selectedIndex = 0;
walkNext(myTree);
// finished ---|
}
}

However, it fails intermittently when trying to negotiate past a parent whose previous sibling is a closed folder.

When this does fail, physically clicking on the currently selected element allows it to work again.

Does anyone have any ideas? Or, is there already some simpler way to do this?

Here is the complete code if anyone wants to try it:


<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:XMLList id="treeData">
<node label="Mail Box">
<node label="Inbox">
<node label="Marketing">
<node label="Marketing and stuff with a long name for wrapping purposes"/>
<node label="Product Management"/>
<node label="Personal"/>
<node label="Personal"/>
<node label="Personal"/>
<node label="Personal"/>
</node>
<node label="Product Management">
<node label="Personal"/>
</node>
<node label="Personal"/>
</node>
<node label="Marketing and stuff with a long name for wrapping purposes">
<node label="Professional"/>
<node label="Personal"/>
</node>
<node label="Spam"/>
<node label="Sent"/>
<node label="test">
<node label="Sent">
<node label="many elements"/>
<node label="many elements"/>
<node label="many elements"/>
<node label="many elements"/>
</node>
<node label="Sent">
<node label="one element"/>
</node>
</node>
<node label="test2"/>
</node>
</mx:XMLList>
<mx:Tree
id="myTree"
labelField="@label"
showRoot="false"
x="111" y="40"
width="800"
height="400"
dataProvider="{treeData}">
</mx:Tree>

<mx:Script>
<![CDATA[
import mx.controls.Alert;

private function goToFirstPage():void
{
myTree.selectedIndex = 0;
walkNext(myTree);
}

private function goToNextPage():void
{
walkNext(myTree);
}

private function goToPreviousPage():void
{
walkPrevious(myTree);
label1.text = myTree.selectedIndex.toString();
}



// recursive method to walk to the next leaf in a tree
private function walkNext(_tree:Tree, _count:int=0):void
{
// increment the count
_count++;
// if this is the first time
if((_count <= 1))
{
// if this is a branch
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
// open the branch
_tree.expandItem(_tree.selectedItem,true,true);
_tree.validateNow();
}
}
// increase the selected Index
_tree.selectedIndex++;
// if this is a branch
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
// open the branch
_tree.expandItem(_tree.selectedItem,true,true);
_tree.validateNow();
// recursion --->
walkNext(_tree,_count);
}
// else if a leaf
else
{
// scroll to the selected index
_tree.scrollToIndex(_tree.selectedIndex);
_tree.validateNow();
// finished ---|
}
}

// recursive method to walk to the previous leaf in the tree
private function walkPrevious(_tree:Tree, _count:int=0):void
{
var t1:int = _tree.selectedIndex;
// increment the counter
_count++;
// if the selected index is greater than 0
if(_tree.selectedIndex > 0)
{
// go back one
_tree.selectedIndex--;
_tree.validateNow();
// if on a branch now
if(_tree.dataDescriptor.isBranch(_tree.selectedItem))
{
// if branch is open
if(_tree.isItemOpen(_tree.selectedItem))
{
// go back one more
walkPrevious(_tree,_count);
// recursion --->
}
// if branch is closed
else
{
// expand the branch
_tree.expandItem(_tree.selectedItem,true,true);
// go forward to original selection (doesn't go into the sub branch as tree not validated yet)
_tree.selectedIndex++;
_tree.validateNow();
//_tree.dispatchEvent(new MouseEvent(MouseEvent.CLICK));
// now go back one
walkPrevious(_tree,_count);
// recursion --->
}
}
// if not a branch
else
{
// scroll to the selected index
_tree.scrollToIndex(_tree.selectedIndex);
_tree.validateNow();
// finished ---|
}
}
// if selected index <= 0
else
{
// go to the next leaf
myTree.selectedIndex = 0;
walkNext(myTree);
// finished ---|
}
var t2:int = _tree.selectedIndex;
}
]]>
</mx:Script>
<mx:Button x="111" y="10" label="Go to First Page" id="fpButton" click="goToFirstPage()" width="800"/>
<mx:Button x="793" y="448" label="Go to Next Page" id="npButton" click="goToNextPage()"/>
<mx:Button x="111" y="448" label="Go to Previous Page" id="ppButton" click="goToPreviousPage()"/>
<mx:Label x="519" y="450" text="Label" id="label1"/>
</mx:Application>


Any help greatly appreciated.



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