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is it possible to calculate a list index from a mouse point [message #731046]

Thu, 29 September 2011 14:52

Mark Fishman
Messages: 25
Registered: March 2011

Junior Member

I have a List component and am trying to implement a capability where a user can click on a selected item and drags it up and down in the list using the mouse. I also need to support if someone drags from another list into this one. I think that I have a handle on most of the problem but I don't see an easy way to figure out the index in the list that I am over when the user does the drop. Does anyone have any suggestions?

Thanks.

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Re: is it possible to calculate a list index from a mouse point [message #731056 is a reply to message #731046]

Thu, 29 September 2011 15:22

Ed Merks
Messages: 24550
Registered: July 2009

Senior Member

<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Here's a utility method we use in EMF that might help get you
started: 
 
/** 
 * This returns the location of the mouse in the vertical
direction, relative 
 * to the item widget, from 0 (top) to 1 (bottom). 
 */ 
protected float getLocation(DropTargetEvent event) 
{ 
 if (event.item instanceof TreeItem) 
 { 
 TreeItem treeItem = (TreeItem)event.item; 
 Control control = treeItem.getParent(); 
 Point point = control.toControl(new Point(event.x,
event.y)); 
 Rectangle bounds = treeItem.getBounds(); 
 return (float)(point.y - bounds.y) / (float)bounds.height; 
 } 
 else if (event.item instanceof TableItem) 
 { 
 TableItem tableItem = (TableItem)event.item; 
 Control control = tableItem.getParent(); 
 Point point = control.toControl(new Point(event.x,
event.y)); 
 Rectangle bounds = tableItem.getBounds(0); 
 return (float)(point.y - bounds.y) / (float)bounds.height; 
 } 
 else 
 { 
 return 0.0F; 
 } 
} 
 
I forget how we deal with list views in EMF. You can always use a
table with a single column... 
 
 
On 29/09/2011 11:52 AM, mfishm1 wrote:
<blockquote cite="mid:j62e2r$j13$1@news.eclipse.org" type="cite">I
have a List component and am trying to implement a capability
where a user can click on a selected item and drags it up and down
in the list using the mouse. I also need to support if someone
drags from another list into this one. I think that I have a
handle on most of the problem but I don't see an easy way to
figure out the index in the list that I am over when the user does
the drop. Does anyone have any suggestions?
 
 
Thanks.
 
</blockquote>
</body>
</html>

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