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.
Related
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
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 idea to implement my wpf windows like TabPages in tab control. It is possible to do that dynamically in c# code.
In Example i have Menu in main window. Some Menu items calls search type windows. Is it possible to do such a thing in C# code (SomeMenuItem_Click): this code adds new tab in tabControl of main window.
If there are no search windows called -there is no tab's shown, if there are many search windows called - there are many tab's.
So how do I code this?
And whats the technique with the windows? I suppose that my search type windows must be implemented like some UserControls. I think its no a good idea to implement that like simple wpf windows. I have tried to do that by using Marlon grech "Blend like UIs using DOCKY", find at:
http://marlongrech.wordpress.com/2008/01/29/create-blend-like-uis-using-docky/
But I failed, dont find the way how to add controlls in code dynamically, not in xaml.
I would appreciate code examples to illustrate how to achieve this.
Is it possible to do such a thing in C# code (SomeMenuItem_Click): this code adds new tab in tabControl of main window.
Yes. The basic pattern is:
TabItem newItem = new TabItem();
tabControl.Items.Add(newItem);
You'll obviously need to set the relevant properties of your tab item (such as the Header and Style) but that should get you started.
You'll then need to create any controls you want to show and add them to the tab item itself (or more correctly - a container within the tab item).
In order to make a convenient UI for an .Net 2.0 Winforms application I am working on, I have need for a control that I'm pretty sure goes beyond the "out of the box" behavior of any standard control. A mock-up of what I'm trying to achieve follows:
Mock up http://www.claware.com/images/temp/mockup.png
Essentially, this part of the application attempts to parse words into syllables from tribal languages (no dictionary to refer to; any and all unicode characters are possible.) By the time the user gets this far, he has already defined the vowels / consonants in his language and some other configuration. There is then an iterative process of (1) the application guesses which syllables exist in the language based on some rules, (2) the user refines the guesses, selecting the correct parsings or manually parsing a word, (3) the application "learns" from the user's feedback and makes smarter guesses, (4) repeat until the data is "good enough" to move on.
The control needs to present each word (the grey headers), then all the syllable break guesses (the white areas with dots separating the parts of words.) There is also a way to manually enter a parsing, which will display a text area and save button (at the bottom of the mockup.) When the user hovers over a guess, the background changes and "accept / reject" buttons appear. Clicking on the accept, or entering a manual parsing, removes the entire word from the list. Clicking the reject button removes just that item.
I'm by no means 100% sold on the formatting I have above, but I think you can get a general idea of the types of formatting and functional control I need. The control will also scroll vertically--there may be thousands of words initially.
My question for you experienced WinForms developers is: where to start? I would really, really like to stay within the .Net core framework and extend an existing control as opposed to a third-party control. (At the risk of starting a religious war: yes, I suffer from NIH-syndrome, but it's a conscious decision based on a lot of quick-fix solutions but long-term problems with 3rd party controls.) Where can I get the most "bang for my bucK" and the least reinventing the wheel? ListView? ListBox? ScrollableControl? Do I need to go all the way back to Control and paint everything manually? I appreciate any help that could be provided!
[Edit] Thanks everyone for the ideas. It seems like the most elegant solution for my purposes is to create a custom control consisting of a FlowLayoutPanel and a VScrollBar. The FlowLayoutPanel can contain instances of the custom controls used for each word. But the FlowLayoutPanel is virtual, i.e. it only contains those instances which are visible (and some "just out of scroll"). The VScrollBar events determine what needs to be loaded. A bit of code to write, but isn't too bad and seems to work well.
I would look at the TableLayoutPanel and FlowLayoutPanel controls. These will let you organize a series of controls with moderate ease in a vertical fashion. I would then create a UserControl that consists of a label and 2 buttons. The UserControl will expose properties like Text and events that are exposed for the button clicks.. For each entry in the list, you will create an instance of the UserControl, assign the text value, and handle the click events. The instance will be placed in the Table/Flow panel in the correct order. Both of those layout panels do allow for inserting items between other items so you can add/remove items from the list dynamically.
Edit:
Given the length of what you are trying to render, I would consider using the DataGridView and do some custom rendering to make it perform how you want it to work. Using the rendering events of the DGV you can merge columns, change background colors (like highlighting the dark gray lines), turn on/off the buttons, and handle changing the grid into edit mode for your rows to allow modification or inserting of new values. This method would easily handle large datasets and you could bind directly to them very easily.
Well, this certainly looks like a candidate for a custom component that you should be creating yourself. You can create this using standard .Net drawing commands along with a text-box, and a regular button control.
Now you want to find out where to start.
Create a Windows Forms Control Library project.
Drop in the textbox and the button control.
The panel drawing code should preferably be done by code. This can be done using the regular GDI+ commands.
Edit:
Here's another idea, and one that I've practically used in my own project with great success.
You could use a web-browser control in the app, and show your data as html. You could update the source of the web-browser control based on the input in the textbox, and clicking on the links in the web browser control will give you the event that you can trap to do some action. Your CSS will work.
I used this technique to build the 'desktop' in an app I made called 'Correct Accounting Software'. People loved the desktop so much that it is one of the best loved features of the app.
Here's how I would do it:
Create a custom control. In this custom control, have a ListBox atop a LinkButton, and when the LinkButton is clicked you can make it give way to a TextBox. The ListBoxes will have the top row unselectable... you can probably get the rest from there. When you get your list of words, fill a Scrollable of some kind with one control for each word:
(foreach String word in words){
myScrollable.add(new MyComponent(word));
}
From there, I'm not sure what you want to do with the boxes or the data, but that's my initial idea on the UI setup.
Use the WebBrowser control and generate the HTML markup into it using DocumentStream or DocumentText.
I have a windows forms application with controls like textbox, combobox, datagridview etc.
These controls allow a user to use the clipboad, i.e. cut/copy and paste text. It is also possible to delete text (which is not related to the clipboard).
My application has a menubar with an Edit item containing Cut/Copy/Paste/Delete items, and a toolbar with these items as well. How can I enable/disable these items properly depending in the state of the control having the focus?
I am looking for a generic way, i.e. I look for an implementation I do once, and can reuse for the future independent of the controls my application will use.
There is no generic interface or set of methods for getting cut/copy/paste information from a windows forms control.
I suggest your best approach would be to create a wrapper class for each type of control. Then when you want to update the menu state you get the current control with focus and create the appropriate wrapper for it. Then you ask that wrapper for the state information you need. That way you only need to create a wrapper implementation for each type of control you use. Bit of a pain to start with but other time you only need to add the new controls you come across.
Clipboard information is much easier as you can ask the Clipboard singleton if it has data inside and what type it is. Then again you still need to ask the target control if it can accept that type of information so there is still extra work needs doing.
Create an array for each enable/disable group. Add the controls to the array (of course it has to be of the correct type such as Object or Any, etc. depends on the programming language you are using).
Then to enable, disable just loop through the array and invoke the enable/disable method or function for each control. Again, depending on the language you may need to cast back.