 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
.NET Forum / Languages / C# / September 2007Filtering ListViewItems
I would like to implement a filter function on a ListView control, and I found this code on TheCodeProject: http://www.codeproject.com/cs/miscctrl/listviewfilter.asp Since it's not possible to toggle the ListViewItem's visibility, the filtering is acheived (in this case) by moving the "non-matching" item to a temporary collection and returning them to the ListViewItem collection when they are no longer filtered out. That approach works ok in this case, because the listviewitems are sorted, but if they are not, the CodeProject code will not work, because items that are reinserted in the ListViewItem collection are merely added and will thus appear at the bottom of the list. Is there any way of easily keeping track of the original order and reinserting the items in their original position? Cheers, Johnny J. Hi, >I would like to implement a filter function on a ListView control, and I >found this code on TheCodeProject: > > http://www.codeproject.com/cs/miscctrl/listviewfilter.asp > Is there any way of easily keeping track of the original order and > reinserting the items in their original position? I can think of a couple of ways to achieve it. Maybe you can remember the index at where the item was when y ou removed it the first time, then when you move it back in you know where to put it. another possibility is to simply rebind the list everything you change it. you hold the "original" list outside and make a view of it that it the one that you bind to the control, when you need to change it you simply do it again. If you use datasets you can use the DataView object to achieve filtering (and binding of course). Or you can create a class using the decorator pattern and add filtering to your data objects. then you simply bind your decorator to the listview. And when you change the filtering options on the decorator, the listview will be update accordingly. > Hi, > [quoted text clipped - 14 lines] > that you bind to the control, when you need to change it you simply do it > again. Unfortunately, the ListView does not support data binding for the items in the views, so this wouldn't do much.  Signature- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com > If you use datasets you can use the DataView object to achieve filtering > (and binding of course). [quoted text clipped - 22 lines] >> the one that you bind to the control, when you need to change it you >> simply do it again. true, however there are implementation for binding to listview. http://www.codeproject.com/cs/miscctrl/ListView_DataBinding.asp is a nice example. > Unfortunately, the ListView does not support data binding for the items > in the views, so this wouldn't do much. [quoted text clipped - 25 lines] >>> the one that you bind to the control, when you need to change it you >>> simply do it again. Sorry I was unclear: Databinding has nothing to do with my question. As Nicholas points out, the ListView is not databindable, and even if it was, it would still not solve my problem. I'm looking for a way to do this without databinding. As for Ignacios suggestion about remembering the items index, it's an idea, but a very complex one. If it was only ONE item that was temoved, it wouldn't be a problem, but now were talking about an undefined number between 0 and all items. So when I want to reinsert an item, I have to iterate through ALL the items that are in the Listview to find out which Items i should insert my item between. And the items that are left in the listview doesn't have their origianl indexes anymore, so i would be forced to match all the items with a table of the original indexes. I can write the code for that, but all solutions I can see are going to take time, thus affecting performance during the filtering process. I guees I hoped that somebody would have a magical solution... ;-) Cheers, Johnny > true, however there are implementation for binding to listview. > [quoted text clipped - 30 lines] >>>> the one that you bind to the control, when you need to change it you >>>> simply do it again. Johnny, I don't think that noting the indexes of the items that are filtered out is that big of a deal. If you cycle through the list items, and remember the zero-based indexes of the items that are removed (along with the items), then you can iterate through that list of items that was removed again, and call Insert on the Items collection with that index. You just have to make sure that as you iterate through the removed items, the index that you are inserting at is incrementing. Every time you call Insert, it will arrange the items between the insert point and the next insert point so that they are in the correct position. Signature- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com > Sorry I was unclear: > [quoted text clipped - 53 lines] >>>>> the one that you bind to the control, when you need to change it you >>>>> simply do it again. Hi, > As for Ignacios suggestion about remembering the items index, it's an > idea, but a very complex one. If it was only ONE item that was temoved, it [quoted text clipped - 4 lines] > listview doesn't have their origianl indexes anymore, so i would be forced > to match all the items with a table of the original indexes. > I can write the code for that, but all solutions I can see are going to > take time, thus affecting performance during the filtering process. > > I guees I hoped that somebody would have a magical solution... ;-) It's not that complex, and you can implement it and share with the rest of us :) Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.