I'm working with quite complex WPF windows with a lot of controls in it.
In my context, the user experience we chose to have is to first display the window, then load the data and databind (while displaying a progress bar).
With the help of WPF traces in Visual Studio, I have noticed that databinding is invoked twice before the window is shown :
when we call InitializeComponent() which parses the XAML.
when we call ShowDialog().
Because there is no data yet, it takes quite some time for the databinding mechanism to try fallback and default values.
In order to speed the display of the window to the user, is there a way to disable the WPF databinding until the window is shown ?
Thanks in advance.
EDIT 1 :
I have more that 400 controls on the form. The call to InitializeComponent() is taking 700ms to complete. I don't know how much of that is tied to databinding, may be I'm mistaken.
EDIT 2 :
According to dotTrace profiler, InitilizeComponent() WPF cost is 65.43% divided in :
34.25% System.Windows
22.57% System.Windows.Markup
8.29% Other
EDIT 3 :
We're down to 272ms for InitializeComponent().
We have a lot of converters, singletons are now used for all of them.
Definitely.
One straight option would be to remove your data-binding-related XAML markup and do the same thing from code-behind, but only after the window has been shown (or on any other condition you find suitable). See this MSDN example on how to databind in code.
Another option would be to not bind to your "real" data sources directly (it's unclear why that would cause a slowdown, but I 'm taking your word for it) but rather to proxy objects that have an on/off switch: start with the switch turned off, making the proxy return empty datasets, and turn it on after the window has been displayed.
Interesting point. Is binding time so large?
In InitializeComponent() DataContext usually is null and it should take milliseconds to resolve binding. The problem likely is in another place.
Using default values in DataBinding mechanism is clear, fast and simple.
Related
I am currently running into an issue where I want all of my tabs to be immediately bound to my ViewModel. For some reason, it seems that WPF doesn't bind my other TabItem's until I select them for the first time. I am eager for a solution in this because I have validation on those others tabs. Until the binding occurs on those other tabs, my app thinks everything is valid when it isnt. If it helps, I am using FluentValidation for my validation.
I have tried using someone's TabControlEx to see if that would help me but it doesn't. I also tried to cycle through all the tabs after I load the data to force the binding but that didn't always work on slower devices. I am not a fan of this solution either.
I don't know why you are being voted down, seems like a valid question, but you will still get a vague answer, due to the nature of the TabControl:
The default style for WPF TabControl only contains a single ContentControl which is used for displaying all tabs. Thus, the visual tree representing a tabs content is created on demand; and tears down to be replaced with a new visual tree when the content/tab switches.
The common issue here, is that switching between tabs becomes slow, and thus there are a couple of solutions out there:
Binding to ItemsSource of TabControl in WPF
https://github.com/ButchersBoy/Dragablz
However, what happens with the solutions is that ContentPresenters are cached...but they still wont be created until a user first hits the tab. Thus, you will still have the same issue.
Thus you need some sort of architectural change. You need your set of view models to be validated from a trigger in code, on initial startup. Waiting for the tab control to render items just isn't going to work for you.
You probably need to bubble the error up in your view model hierarchy to display in the TabItem.Header or in the window itself; perhaps you might have a MainWindowViewModel where you can display a top level error.
I am creating a windows form, that contains a simple combo box, which has around 100000 items. After loading all those items when I try to show the form useing showDialog() method it is taking 30 sec to show the form.
Is there any way that I can show it immediately ?
As pointed out by #jmcilhinney, it is not practical to load all this data to a combobox. Your system could (and it is) getting unresponsive on other situations.
There might be a lot of reasons for you have to do this, and since you are not disclosing everything, I can give a suggestion to answer your question - remember, not the good way, but would make things better for a while.
You might be binding your information on your load process. Separate it, make it async.
There are several ways of doing this, like making an async call to a internal method and set your ComboBox.DataSource or ComboBox.DataBind.
Also, on the end of your load/initialization of your window, set the cursor do hourglass/wait. Then set it back to the original one (might be the normal pointer). This would give the effect that the dialog is shown but it is yet loading. It is a lot better for the user showing that you are loading info.
But after that, try filtering data as you type, as suggested by #jmcilhinney. Even if it a fixed list, make it editable and filter data. Don't let the user see more than +1000. You should find a way to show the user that has too much thing and provide means to make your data filterable.
If you have data loading code for combobox in the load event, which I think you do. Move that code to a separate function and call that from a timer or thread. Or you can make the function async and then call that function from load event. This will not keep your form waiting till all the data is loaded in the combobox.
I was wondering if there is any difference between adding some controls/usercontrols (that take time to initialize ) in XAML or constructor and in Loaded event of some window.
I have a window where I use same usercontrol thrice. This is a usercontrol and takes some time to initialize itself. This window takes around 5 - 7 seconds to initialize itself with all three usercontrols initialized.
How should I approach adding them in window?
( Someone suggested that adding control after window is loaded will allow window to load in faster way than adding them in XAML/Constructor of the window.)
I would like to have some suggestion from experts on this topic as I don't know much about this.
Thanks.
There is nothing inherently wrong with deferring the loading of a window's content until after the window has been shown. The event you probably want is ContentRendered, which tells you the window's handle has been created, and the window shown.
I would suggest wrapping your window's content in a single "view", say a UserControl, such that you only need to set the window's Content and be done with it, as opposed to imperatively injecting multiple controls. It just makes things simpler. In essence, make your view a user control, and treat the window as the host of your view.
None of this is likely to reduce the time required to populate your window, but at least you'll be able to show something while the content is processed, even if it's just an empty window with a wait cursor.
Also, look for any places where you perform expensive operations on the UI therad (e.g., in your views or view models), and consider replacing those with asynchronous operations. You might find that you're able to load the UI faster than the underlying data, in which case you can display a more complete view with the appropriate wait/progress indicators until your data comes in.
Hi guys I have a problem
i need the info I enter in a text box on my main window to update a label on my second window called script.
The text box name is client and the label name is client-label
I have tried many different ways to do this and still not coming right
how can I do this?
PS. I am new to the programming world so please give me step by step instructions anywhere possible :)
Pertinent to your requirement (i.e. two WPF windows with sync controls), it will require quite a bit of coding. Better (simpler) way is to create a pseudo-window, i.e. just a nested layout Grid within you main window containing all controls pertinent to that second window (you can set its visibility to collapse/visible in order to "simulate" pop-up window), and update a second TextBlockon .TextChanged event of the first TextBox (using code behind). Alternatively, you can apply data binding technique is XAML of the same single window.
Note: you can implement a splitter control to resize two 'sub-windows'.
In case you do prefer to implement second window, then refer to this example: Data Binding between two TexBoxes in different windows
Rgds,
The "correct" way for this would probably be to have a view model for each view part in your gui and have them communicate through events.
The Prism framework for WPF will help you with most of the plumbing for this.
Se more about Prism here: http://compositewpf.codeplex.com
I have a program that loads a tab that has roughly 332 text boxes it loads. When loading a new tab there is a 2-3 second delay before the tab can be displayed. I have tried to suspend and resume and even looked into threading but found out that a winform can only use one thread.
I was wondering if there was a way to create the text boxes in another thread and then add them into the main form or a way to better create 332 text boxes.
thanks for your help.
Depending on your layout, I'd strongly recommend replacing the textboxes with a DataGridView, or otherwise loading the textboxes on scroll with some kind of continous-control .
The main bottle neck is the creation of handles. In winforms, each control gets its own handle (even labels), and when used in large numbers such as this, can indeed give performance problems.
If a datagridview is not an option, can you give some more information on the layout (a screenshot perhaps?), so the community can have a go at alternatives. Creating the textboxes in another thread will create problems when you try to add them, but you could create them only when needed.
Simple: don't use 300 text boxes. You can only use one text box at a time. The rest of the data you can just draw, and when the user wants to edit it you create the edit control for it. This is exactly how a grid works, so I recommend using a grid or similar control.
I also had this problem, and it goes further to affect initialisation code for controls on tabs that has not get activated before.
My workaround is to block the program with a "loading..." splash and programatically click the tabs so that the controls get loaded/activated. Once this is done, the tabpage shoud not take as long to display again.
Although I agree with others in that you may want to look into reducing the number of controls in a single tab.