I have a treeview and a textbox. As I type in the text box it updates the tree view in real time (filtering by what I type and matching against the objects in the tree view).
The problem is it starts freezing a bit as I'm typing in the box. ie. while the treeview is updating the text box freezes. I have put the logic that populates the treeview in another thread hoping this would make it run a bit faster - which it did, but not enough. I believe it is the actual UI updating which is causing the responsiveness to diminish.
What are some ways that I can tackle this problem? Is it possible to have different UI elements (in this case, the treeview and the textbox) handled in different threads - rather than just the logic which is the case now?
Thanks
Your problem is that only one UI thread exists!
A possible solution to your problem is to filter the treeview after a few milliseconds after the user has made a text input.
Another possibility is to make the filtering in a separate task and the result of the Treview reassign.
I hope this helps you with your problem.
Related
I have a TreeView which holds approximately 100,000 TreeNodes or even more, I have optimized everything related to loading or unloading them on deserialization process but now I'm stuck with an issue I can't overcome.
Its important to mention I decided not to use the LabelEdit default event given by the control since its pretty tricky to make it work as I wanted to, Its widely known that there are a lot of "problems" with this particular event which have pushed many devs to implement their own custom TreeViews.
In my case I am using a ContextMenu which has a Rename option, this brings a textbox right in front of the TreeNode and then I just simply change the TreeNode.Text property to whatever the user input was in the TextBox keydown event, once we trigger this event, the whole GUI freezes for a couple of seconds (4-5), I'm not doing any Depth search over the TreeNodeCollection or anything, I am directly accessing the TreeNode and modifying the property...
So, any thoughts on what could be wrong here? I already tried BeginUpdate / SuspendLayout / or even a custom solution found here How do I suspend painting for a control and its children? and nothing seems to help.
The first thing that comes to mind is that when the text is changed on the node, it must be redrawing the entire treeview.
In this situation, suspendlayout will not help, as the control isn't laying its contents.
I think beginupdate stops the drawing when nodes are being added to the list, but the text changed might bypass this.
Have you considered not using the keydown, and just updating the text once the user has dismissed the textbox? (i.e. done editing). Not ideal, but will limit the performance hit to once, instead of every key stroke?
I have a form with 2 tabs. The first tab is boring, the second tab (unseen as default to the user) contains many comboboxes.
Using the FormLoad() event I populate a combobox on the second tab (with around 11,000 items/strings) on a background thread. The sql command to do this is also asynchronous.
Now, in theory this should mean that when the user finally gets round to clicking the second tab (whether that be in 10 seconds or 10 hours) they should be instantly presented with a nicely populated control - but there is ALWAYS a 4 second delay. I just don't get it! If all the heavy lifting is done via the background thread (the whole reason for using them in the first place!), why the heck is my application still slow and unresponsive when the user clicks that darn second tab??!!?!
*Bearing in mind you have to give the application a chance to fill the combo in the first place, plus I know when it's finished populating as the backgroundWorker1_RunWorkerComplete() method fires and sends a debug message to tell me all work has finished.*
Any help will be much appreciated....
11,000 is a lot! The work has been done to populate the comboBox items on the background thread, but the form still has to show all those items. This means the UI thread has to render a proportion of them (or all of them) to the UI (into memory) ready for scrolling; this is what is taking time.
I would suggest overriding the ComboBox control and handling the scroll event yourself. This way you can load a subset of the entire list sequentially when you need them (if that is possible in your case). This will prevent the four second delay you speak of.
At a high level my application is applying about 5 different DataTemplates to a set of ListBoxItems based on their type. These items are laid out on a canvas at specific x, y points. I implemented virtualization on my ListBox and it did not seem to improve the time it takes to complete the rendering thread's processes. It still takes about 8-12 seconds for the UI to be completely loaded and usable by the user. I thought virtualization would help fix this problem but after looking around it looks like it only helps process scrolling large amounts of data. Am I correct in this assumption and does anyone else have any other tips for improving the rendering thread. This is the only problem I am having and then my project is complete. Thanks StackOverflow!
Virtualisation means that only the items you have visible are created, then dynamically destroyed/new items created as you scroll. The alternative is all UI controls are created for all items at once.
It sounds like you have bigger problems with the rest of the app. Do you perform all loading operations on a background thread? Is the UI control tree very complex indeed? Are you displaying 100s or 1,000s of items?
We also had a lot of trouble with performance in WPF. Best way is of course to profile your application. We use ANTS Performance profiler for that, but any .NET profiler will do. We got a huge performance hit, because of the lookup of our XAML Resources. Thats the advice i can give you:
Try to minimize all resources in XAML. But not only that, also try to minimize the amount of XAML files you have. One thing you can try is to defere the loading of complex parts of your DataTemplate. Similiar to what happens when you load a JPEG in a browser, first you will see a pixelated image which will be finer after it finished loading the JPEG. To accomplish that, use a simpler DataTemplate at first and then if this is visible only load the complex template on demand or after a while.
But without more information of your specific problem, we can only guess. This is an old question of mine about a similiar subject, maybe this will help aswell.
Yes, ListBox virtualization is for scrolling. When you have a large number of items in a ListBox, enabling virtualization will make only the visible items (+ a few extra items for scrolling) render, and scrolling the ListBox replaces the data in the rendered items instead of rendering new items.
If you were to post some code, perhaps we could assist you with some performance tweaks
I have a WinForms data entry form that will have upwards of 1500 questions. I have the questions broken into sections, and each section will have an unkown number of questions. Each section is its own user control and has rows (2 panels, 2 labels, a textbox, and another user control) created and added dynamically for each question. The section controls are then added to the form.
My problem is that the process takes a lot of time, even with using TPL (Task Parallel Library). I would ultimately like to create/add the controls and allow the user to start entering data at the same time. The controls are going into a scrollable panel. While the user is entering data, that data will need processed on a local database...so more threading could be necessary.
I have tried working with TPL, which I am new to, by having all the controls added to a list during processing and then sorted and added to the form after the Parallel.ForEach was complete...takes about 20 seconds for over 1200 questions.
I also tried utilizing a BackgroundWorker component. Using the BWC seems to be the faster of the two, but there is a race condition for the ProgressChanged() eventhandler and not all controls get added...not to mention the way the form looks with all the rerendering.
Am i just using TPL wrong? What's the best way to go about this? Is there another way or do I just make the user stick out the wait?
Thanks
Am i just using TPL wrong? What's the best way to go about this? Is there another way or do I just make the user stick out the wait?
Most likely, you can use TPL, and get the same response time as BW, but a nicer API for this type of operation.
The trick here is to get a TaskScheduler setup for UI interaction, and then use the Task class to push the controls back onto the UI thread as they're ready. I have a blog post on this specific subject which shows how to get a TaskScheduler setup to use with UI threads.
However, I would recommend keeping these in memory and pushing them in batches, to avoid constantly re-rendering the UI. This is likely to be an issue no matter what you're doing.
That being said - I'd question your overall visual design here - if you're trying to display over 1200 questions to the user, some form of paging is probably a much nicer approach than a huge scrollable container. If you page these, you could load and process the first few (which is probably near instantaneous, since you mentioned you can process about 50 questions/second), and then continue loading the others after the first few questions have been displayed.
I want to create a control which takes a while to create (Pivot) and then add it to the visual tree. To do this i would need to change the dispatcher of the control (and its heirachy) before adding it to the VisualTree.
Is this possible? Are there any implications of walking the controls trees and setting the _dispatcher field via reflection?
AFAIK this only works with Freezable derived classes. The best solution I see is to create the control on the UI Thread and show a progress bar during creation. To make this possible you will have to create the control in portions an let the progress bar update itself once in a while. This not only necessary for the progressbar but also will make sure that you application does not block.
Pseudocode (execure in extra thread):
this.Dispatcher.BeginInvoke(UpdateProgress(0));
this.Dispatcher.BeginInvoke(bigControlBuilder.Build(0,25));
this.Dispatcher.BeginInvoke(UpdateProgress(25));
this.Dispatcher.BeginInvoke(bigControlBuilder.Build(25,50));
this.Dispatcher.BeginInvoke(UpdateProgress(50));
this.Dispatcher.BeginInvoke(bigControlBuilder.Build(50,75));
this.Dispatcher.BeginInvoke(UpdateProgress(75));
this.Dispatcher.BeginInvoke(bigControlBuilder.Build(75,100));
this.Dispatcher.BeginInvoke(UpdateProgress(100));
this.Dispatcher.BeginInvoke(this.Children.Add(bigControlBuilder.GetControl()));
Update:
To make complex control more responsive you could also try UI-Virtualization/Data-Virtualisation:
Only load and show those visual items of the data items that are currently visible to ther user. Do not load and show visual items that are scrolled offscreen are to small to see or are in any other way invisible to the user. Upon userinteraction unload items that become invisble, load items that become visible.
To answer your question, I suppose it is possible to set _dispatcher using reflection but I would not recommend it at all. There is a deeply ingrained notion in WPF of thread affinity and STA so I wouldn't mess with that.
bitbonk's approach is a good one.
Another approach we have used in a project of ours was to create a second UI thread and have a progress indicator be rendered by the second UI thread while the first UI thread is building the UI. As long as the progress bar stays in the visual tree owned by the second UI thread, you should be good.