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.NET Forum / Windows Forms / WinForm Controls / June 2008How to disable (Auto)Scroll for a DataGridView
Hi Group, I am using C# with .NET 2.0 and Visual Studio 2005. I have a GUI with a DataGridView (DGV) and a BindingSource for the data. The data are added programmatically, up to 5 rows per second. My question are: How do I disable the automatic scrolling of the DGV? It seems that each time I add a new data record, DGV scrolls to the position of that new record. How do I prevent the DGV from keeping the position of a selected row (each time I add a new record, the DGV scrolls back to the selection). What I want at the end is a DGV which shows a scroll bar but does not do ANY automatic maintenance of it. The user alone shall decide what portion of the DGV is shown even if the data are added, removed selected or what else... Thanks for any ideas! Regards, Paul Paul, That's kind of interesting. So you're adding data to the DataGridView in real-time while the user already has the form open? You do that in a separate thread? I'm not sure this matters, but how are you adding records to the DGV? Are you just adding the records to the DataTable connected to the DGV by the BindingSource? Also, why does it take a full second to load 5 rows? That seems really slow. Is your DGV sorted? Or do new records always pop into the DGV at the bottom? I'm curious to hear more about your application. I think what you want to accomplish with the DGV is probably possible, but I also have a feeling that you might be able to solve your problem by employing a different strategy that doesn't involve tweaking the DGV. Patrick > Hi Group, > [quoted text clipped - 20 lines] > Regards, > Paul Hi Patrick, > That's kind of interesting. So you're adding data to the DataGridView in > real-time while the user already has the form open? You do that in a > separate thread? Yes, the data are produced in a separate thread. > I'm not sure this matters, but how are you adding records to the DGV? > Are you just adding the records to the DataTable connected to the DGV by > the BindingSource? The data are added to the binding source, it looks like: // get the binding source BindingSource bindingSource = (BindingSource)this.DataSource; // add new message at the beginning bindingSource.Insert(0, ${record}); A new message is always added to the top of the table. Thus, older records are moving down. > Also, why does it take a full second to load 5 rows? That seems really slow. This is just because the external data source delivers not faster than 5/sec max. > Is your DGV sorted? Or do new records always pop into the DGV at the bottom? It's not sorted. New data are placed on the top. > I'm curious to hear more about your application. I think what you want > to accomplish with the DGV is probably possible, but I also have a > feeling that you might be able to solve your problem by employing a > different strategy that doesn't involve tweaking the DGV. I think the problem I have has nothing to do with the data themselves. Its more how the DGV works and how it handles scrolling and selection. Regards, Paul Paul, I've been able to add records to the bottom of a DGV, and it doesn't scroll. From the user's POV, they have no idea new records were added unless they purposefully scroll to the bottom. But adding new records to the top of a DGV is more complicated. The currently visible records MUST move down, which disturbs the user's viewing experience. Maybe rather than adding the new records to the DGV as they "arrive", you could store them, and then have another thread that activates every 5 seconds, takes all the new records waiting in storage and appends them to the DGV. So you add your new records in bursts. Use FirstDisplayedScrollingRowIndex to find the index of the row that is currently on the top of the visible area of the DGV, then immediately after you add the new records, set FirstDisplayedScrollingRowIndex to that index plus the number of newly added rows. It should happen fast enough that it won't impact the user's experience. Here is the general idea: void ThreadThatActivatesEveryFiveSeconds() { int currentIndex = DGV.FirstDisplayedScrollingRowIndex; int numberOfNewlyAddedRecords = AddPendingRecordsToTopOfDGV(); DGV.FirstDisplayedScrollingRowIndex = currentIndex + numberOfNewlyAddedRecords; } Thanks! Patrick Hi Patrick > I've been able to add records to the bottom of a DGV, and it doesn't > scroll. Me too. The problem is not adding the records but the fact that the DGV scrolls to the last manually selected record each time a new one is added. To reproduce the behavior that I encounter and do not like try this: - Run your DGV app. - Select one (or more) record(s) with your mouse. - try to scroll to another position inside the DGV. -> "autoscroll" will scroll back to your selected record right after a new record was added. --> I hate this behavior and want to turn it off. I don't know how. --> Disabling selection by the user is not option because I need selected records for further processing. Regards, Paul 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 ...
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