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.
Related
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.
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
My aim is to make a editor behave similar to MS-Word.Wpf RichTextBox is a wonderful control for it.By placing it inside a ScrollViewer,we can make it editable.(Like a notepad).But I need MS-Word like pages.One effective way probably is to apply style to scrollViewer such that we create a look and feel of multiple pages on richtextbox but I dont know how to do it.What we are doing in the project is to use a documentViewer. Inside a FixedPage,create a Header(Canvas),Body(WpfRichTextBox),Footer(Canvas). And thus create multiple pages,and by subscribing to RichTextBox sizechanged event, we are manually doing the pagination i.e move the blocks from one page to another when height has changed. Do you see any better approach in doing this? Does using multiple richtextboxes hamper my performance?
#WpfProgrammer This is the good approach I would say. Say if you have 1000s of pages then, there will definitely be a performance problem. For avoiding that problem, you need to do demand paging.
Virtual Paging :
1. You need to construct a page table, which will contains pages. Each page will contains information about the controls, images, their positions, dimension and Styles for the page. [All serializable data]
2. Virtual Pages - You need to
de-serialize all the data for the
page and create a page with
RichTextBox. Virtual Pages are
nothing but, pre-cached pages that
are going to be rendered. Say for
example. If I'm in 1st page. Then,
I'll de-seriealize next 3
consecutive pages and have them in a
collection. Then, repeat this
procedure for consecutive page
movements. Adding some logic using
Most Frequently Used collection. It
will be fast enough. In the case of
1000's of pages. You can collapse
those non-dirty or never visited
pages. That could yield little more
performance. If performance is far
more concern for low hardwares.
Then, you should consider
cleaning.
3. Cleaning -
Cleaning is the process of
identifying LFU pages and remove
them. This would be very helpful if
performance is more pronounced.
Hi Tameem
Set the min height,width of the richTextBox to A4 size(lets say). Subscribe to RichTextBox Size Changed event.As soon as the content exceeds,this event gets fired.Then I take the last block of previous page and push it to the first block of next page.(Remember if page doesnot exist, you need to create new page then add it as first block).And also the focus should be changed to the new page.(because if you press enter at the last RTB, you expect the focus to be there in the new page.).When the user deletes a block in some page(say 2nd),then you need to add all the blocks of bottom pages to this page,so that our pagination logic will push the blocks down again and adjust. I can share some piece of code if you need further help.
My app has many controls on its surface, and more are added dynamically at runtime.
Although i am using tabs to limit the number of controls shown, and double-buffering too, it still flickers and stutters when it has to redraw (resize, maximize, etc).
What are your tips and tricks to improve WinForms app performance?
I know of two things you can do but they don't always apply to all situations.
You're going to get better performance if you're using absolute positioning for each control (myNewlyCreatedButton.Location.X/Y) as opposed to using a flow layout panel or a table layout panel. WinForms has to do a lot less math trying to figure out where controls should be placed.
If there is a single operation in which you're adding/removing/modifying a lot of controls, call "SuspendLayout()" on the container of the affected controls (whether it is a panel or the whole form), and when you're done with your work call "ResumeLayout()" on the same panel. If you don't, the form will have to do a layout pass each and every time you add/remove/modify a control, which cost a lot more time. see: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.suspendlayout(VS.80).aspx
Although, I'm not sure how these approaches could apply when resizing a window.
Although more general than some of the other tips, here is mine:
When using a large number of "items", try to avoid creating a control for each one of them, rather reuse the controls. For example if you have 10 000 items, each corresponding to a button, it is very easy to (programatically) create a 10 000 buttons and wire up their event handlers, such that when you enter in the event handler, you know exactly which element you must work on. However it is much more efficient if you create, lets say, 500 buttons (because you know that only 500 buttons will be visible on the screen at any one time) and introduce a "mapping layer" between the buttons and the items, which dynamically reassigns the buttons to different items every time the user does something which would result in changing the set of buttons which should be visible (like moving a scrollbar for example).
Although, I'm not sure how these approaches could apply when resizing a window.
Handle the ResizeBegin and ResizeEnd events to call SuspendLayout() and ResumeLayout(). These events are only on the System.Windows.Form class (although I wish they were also on Control).
Are you making good use of SuspendLayout() and ResumeLayout()?
http://msdn.microsoft.com/en-us/library/system.windows.forms.control.suspendlayout(VS.80).aspx