I'm trying to build a maintenance form in WPF, using Telerik's WPF controls. The idea is to have a grid and a form that are bound to the same collection. Changes to the grid should be immediately reflected in the form, and vice versa. An online example using Telerik's Silverlight controls is here.
My specific problem is that when I enter a new record (by clicking on the "Add" icon in the upper-right of the DataForm), the record is added to both the grid and to the form's collection, but it seems to break the synchronization. The new row in the grid stays highlighted, like the grid thinks it's not done being edited, and while changes to the current record in the form are reflected in the grid, changes to the current record in the grid are no longer being reflected in the form.
But my real problem is more general than that. WPF controls, like Telerik's, are heavily dependent on binding, and in having what they bind to support specific behaviors. In this case, the underlying record needs to support INotifyIEditableObject, so that when the user hits the Cancel button on the form, the EditCancel method on the record can be called. Which is then responsible for setting its properties back to what they had been, and then raising a NotifyPropertyChanged event, so that controls that are informed that they have been so set.
When I didn't have EditCancel working right, I would hit cancel on the form and the values in the grid would not be changed. My guess as to what is going on with the inserts is that something in either my collection or by records doesn't support whatever it is that makes this work. The grid doesn't know that the form has finished editing the record because either my record or the collection hasn't told it.
And here's the real question: how can I find out what these third-party controls are expecting? Telerik's RadGrid can be bound to pretty much anything that can be IEnumerated. But all this neat enhanced functionality depends upon being bound to collections that are very much more specific. I don't get errors, when I bind to a collection that lacks facilities that are needed for certain functions to work, I just get a control that doesn't work.
How can I tell, when working with someone else's control, for which I do not have source code, what functionality it requires, in the objects it binds to?
Your best bet would be to browse Telerik's documentation or ask on their support forums
If that doesn't work, I like to use Snoop for debugging WPF's Visual Tree and Reflector for looking through compiled libraries
Related
I've been creating an inspection form using WPF and I need a place where users can type an unknown amount of comments (hence why I'm not using textboxes). In my WinForms version of this application, I used a DataGridView and I could enter in as much information as I wanted to. I'm looking to do the same with a DataGrid or an equivalent control in WPF.
WinForms Example
I need to be able to do the same thing in WPF but I can't seem to add any rows in the DataGrid. On top of that, when I try to check CanUserAddRows it unchecks it immediatly.
So I checked out Vincent Sigal's blog post about this issue. He mentions something interesting:
... but beware of CanUserAddRows and CanUserDeleteRows as they can appear a little magical. Their values are coerced based on other properties such as DataGrid.IsReadOnly, DataGrid.IsEnabled, IEditableCollectionView.CanAddNew, and IEditableCollectionView.CanRemove. So this is another thing to watch out for when editing. If you run into a situation where you set CanUserAddRows or CanUserDeleteRows to true but it is changed to false automatically, check that the conditions below are met.
I verified this and my DataGrid is not read-only and it is enabled. Although, I have no idea where to find the IEditableCollectionView.CanAddNew and IEditableCollectionView.CanRemove ...
I don't think my situation should require a binding event on the DataGrid since the user is supposed to enter his comments directly into the DataGrid ... Is what I'm trying to do even possible? Perhaps I should use a different control?
I have to admit that I stopped reading through your question after the first paragraph, so please forgive me if I have understood you wrong... but if you just want to enter multi line text into a TextBox in WPF, you can do it by setting a couple of properties on it:
<TextBox TextWrapping="Wrap" AcceptsReturn="True" />
For a DataGrid, you can set these properties in the DataGridTextColumn.ElementStyle and/or DataGridTextColumn.EditingElementStyle as the WPF DataGridTextColumn multi-line input post shows quite nicely.
Please let me know if I did misunderstand you.
UPDATE >>>
Ok, so I came back to read the rest of your question... answering without reading the question can be risky business on this site. It's just as well that I did too, as I see you also want to know how to use the DataGrid.
I have to start by saying... take a deep breath... WPF is very different to WinForms... very different. In WPF we manipulate data rather than UI objects, so to add a new row actually means adding a new item to a collection. You can find a complete working example on the DataGrid Class page on MSDN.
Please also view the WPF DataGrid Control page on WPF Tutorial.NET for more examples. WPF has a lot to take in for new comers and can be quite bewildering, but it's well worth the trouble when you get into it.
I have a custom list control derived from Control class.
I need to make it accessible to people with disabilities through MSAA (Microsoft Active Accessibility).
So far I understand that I need to create class that inherits from ControlAccessibleObject and then return its instance in Control.CreateAccessibilityInstance method override.
The problem is that I have implemented this and it seems not work with Windows Narrator tool.
For example, when I click on an item in standard ListView, the Narrator speaks out the selected item text.
But when I click on item in my control, nothing happens (although the item text is requested in my ControlAccessibleObject implementation)
I thought I need to implement IAccessible as well, but I looked on .NET refrence source code and the ListView does not implement this interface. I thought maybe this is implemented in the wrapped Win32 control, so I took a look on similar control - DataGridView - but this does not implement IAccessible as well.
DataGridView have accessibility support, but although I copied all the important code of DataGridViewAccessibleObject, it still does not work in my control.
Do anyone have more experience with custom control accessibility in WinForms?
Okay, I found it: The Control.AccessibilityNotifyClients method does the magic. One have to override this method in a derived control.
However, to make screen readers speak the text, I had to call:
AccessibilityNotifyClients(AccessibleEvents.Focus, index);
AccessibilityNotifyClients(AccessibleEvents.Selection, index);
Here the index is an index of newly selected item.
I found this code in the .NET reference source of CheckedListBox. When I used Focus or Selection event solely, the screen reader have not reacted. The spoken text also depend on the AccessibleObject state that corresponds to a newly selected item.
The winforms DataGridView has a virtual model and uses the OnCellValueNeeded method to gets cell values from a a user defined data store.
How do i do this in wpf? The DataGrid doesn't seems to have a OnCellValueNeeded method.
Thanks
Not sure if this already helps you:
DataGrid uses UI virtualization, what means that objects are not created before they are visible on screen and the corresponding properties of your source objects will not be called as long as they are not visible. It means also that ui-elements are recycled after they are no more visible.
This is for free and you don't have to do additional coding to use this feature. If I interprete your question right, the main question is, how to know that a property of a business-object is needed. For UI-virtualization, this is when the property is called the first time - You can do some lazy initialization. But beware to put too heavy initialization code into the properties (DB synchronous lookups etc), otherwise your DataGrid will become very slow and unhandy.
I am eager to find some solid (free, Open Source, or tutorial/example) code to make a WPF Combobox do autocomlete/autofilter as the user types. But everything I've tried so far has had some sort of problem...
A Reusable WPF Autocomplete TextBox came close, but I can't get it to work with more than one filter (more info here).
WPF autocomplete textbox/combobox doesn't work for me because it inherits from UserControl, and thus doesn't support the DataTemplates I need (for showing/selecting the value of one property for an object with multiple properties).
Automatically Filtering a ComboBox in WPF didn't work because it doesn't seem to ever find the EditableTextBox portion of the inherited ComboBox code (via (TextBox)base.GetTemplateChild("PART_EditableTextBox") which seems to always returns null).
Building a Filtered ComboBox for WPF just gets stuck in a refresh loop then overflows the stack after I type just a few letters.
Other things I've considered:
I know that Windows Forms' Combobox control has AutoCompleteMode and I could embed it in WPF, but I can't imagine it would play very well with my WPF data bindings.
Perhaps it is too complex and I need to simplify, maybe by building one-dimensional (single-property) ObservableCollections for the ComboBoxen... However, the challenge of applying multiple filters (one set by another control's value, and one from what the user is typing) to multiple controls using different views of the same DataSet would require a ridiculous amount of processing power to destroy and rebuild the list every time the user types a character!
So... I'm at wit's end. Any suggestions?
If your Combobox has some data source attached to it ,
just make
1-IsTextSearchEnabled = true.
2-IsEditable = true.
you are good to go
Try this one:
http://blogs.windowsclient.net/dragonz/archive/2010/02/23/autocomplete-textbox-control-for-wpf.aspx
I have a following requirement for a very complex UI. (Complex here means there are lot of controls in the form [approximately 100]). I am using MVVM (if my problem requires it to slightly go away from MVVM I am ok with it)
My question is for Editable ComboBox and TextBox. But I would say I like to hear a common algorithm which will fit all controls.
Requirement 1 : The user edits the content and goes to next control, the color of the control/text should become red.
Requirement 2 : When the user comes back to the previously edited control and enters the value which was initially present, the color of the control/text should become back to black.
I know the requirement is tough and I have been breaking my head to design a generic algorithm using which I can store the previous value and call a function to change the color of control.
To just give you all an idea, --> I tried storing 2 properties for every TextBox like Default_Text and Text. But since the number of properties are huge, the memory footprint is very huge. Also maintaining so many properties is very tough.
--> I tried adding a Dictionary to every ViewModel to store what values have got changed. But here the problem I faced was giving unique keys to all the controls in my application, which is not very helpful
--> I had even thought and tried about subclassing controls like TextBox, ComboBox and overriding some methods to suit my requirement, but sadly I failed miserabley when I started adding validations and all.
So here I am stuck with designing a generic WPF property system/algorithm to handle all undo redo functionality, changing styles of controls,etc!!!
It will be really great if you experts can guide me in right direction and also help me in developing such an algorithm/system. A sample illustration will be nice though!!!
I found an answer to the above problem. I used attached behavior for this. More details on this link Function call from XAML from StackOverFlow.
When I databind, I store the initial value of the DataBound variable in the Tag property by using Binding=OneWay. Then I have written a attached behaviour for LostFocus event. Whenever the user enters a control and then goes to other control, it fires LostFocus event and calls my attached behaviour. In this, I check whether the value is equal to the value in Tag. If it is same, I display in black else I display in red.
Attached Behaviour rocks in WPF. I can achieve anything from that cleanly without code cluttering!!!!
Another alternative is to use some "dirty" tracking in your models (or viewmodels) and bind to a properties isdirty (and convert it to a color).