Making UserControls accessible in WPF - wpf

Question

I have a WPF form, which consists of a grid of two columns.
In the left-hand column are the control labels, and in the right-hand column are my controls.
The controls are all UserControls. In the simplest case, some of these controls simply wrap existing WPF controls such as the textbox, so that they all implement a common interface.
When the form is generated, I have code like this to set the label for the associated control, where newControl is the created UserControl and ctl.Caption simply returns the required label text:
Label newLabel = new Label();
newLabel.Content = ctl.Caption + ":";
newLabel.Target = newControl;
One problem is that setting the Target doesn't actually work. If I have an underscore in the caption, the mnemonic key doesn't set focus to the wrapped control. One workaround for this may be to manually set the focus to the wrapped control within the UserControl code - but...
The biggest problem is accessibility. Screenreaders such as JAWS, and Windows built-in Narrator, do not read the control caption when the control receives focus.
I have had a look at this: http://msdn.microsoft.com/en-us/library/windows/desktop/gg712258.aspx - which provides a lot of detail, but no helpful examples. It has a lot of stuff about custom controls, which is surely overkill for a simple user control?
So, how can I "attach" my labels correctly to my UserControls?
You can browse the code for the entire project at http://quest.codeplex.com/SourceControl/changeset/view/676933506953 - the particular code is in the EditorControls project, and the UserControls are instantiated in ElementEditor.xaml.cs.

Answer 1

Your newControl is of type Control that doesn't allow you to add additional content.
If you want to add some content to it you need to use a class that supports it, like ContentControl or Panel (for multiple childs) you can implement you own control that implements the IAddChild interface.
A simple solution for you problem could be :
<UserControl x:Class="UIMocks.MyCustomControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel x:Name="content"/>
</UserControl>
The code-behind
[ContentProperty("Children")]
public partial class MyCustomControl : UserControl
{
public MyCustomControl()
{
InitializeComponent();
}
public UIElementCollection Children { get { return content.Children; } }
}
and then you can use
MyCustomControl newControl = InitialiseEditorControl(ctl);
...
Label newLabel = new Label();
newLabel.Content = ctl.Caption + ":";
newControl.Children.Add(newLabel);

Answer 2

hmmm I tried to reproduce your issue on a small test project, but for me it works... so I guess you'll have to give more details on how your userControls are built. Here is what works for me:
I created an Empty project (just the App and Window files, as usual) and set up a grid with 2 columns in my window:
<Window x:Class="Test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow"
Name="Window"
SizeToContent="WidthAndHeight">
<Grid Name="MyGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="100" />
<ColumnDefinition Width="100"/>
</Grid.ColumnDefinitions>
</Grid>
</Window>
then created a userControl that extends the wpf TextBox class:
<TextBox x:Class="Test.MyTextBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
</TextBox>
and:
using System.Windows;
using System.Windows.Controls;
namespace Test
{
public partial class MyTextBox : TextBox
{
public static readonly DependencyProperty CaptionProperty =
DependencyProperty.Register("Caption", typeof(string), typeof(MyTextBox), new UIPropertyMetadata(""));
public string Caption
{
get { return (string)GetValue(CaptionProperty); }
set { SetValue(CaptionProperty, value); }
}
public MyTextBox()
{
InitializeComponent();
}
}
}
it's basically a textbox with a "Caption" dp.
and now in My window's code behind:
public MainWindow()
{
InitializeComponent();
MyTextBox tb = new MyTextBox { Caption = "_Foo", Width = 100 };
Label lb = new Label { Content = tb.Caption + ":", Target = tb };
MyGrid.Children.Add(lb);
MyGrid.Children.Add(tb);
Grid.SetColumn(lb, 0);
Grid.SetColumn(tb, 1);
}
and with this, I do get focus on the TB when I press ALT + F (I can even see the _ under the F of "Foo" in the Label when just pressing ALT)
So I guess your issue has to do with your UserControls themselves and how they are built (what Template for instance)
Edit:
If your control is not extending an existing control but rather contains a WPF control, the issue is probably on the Focus method. You should add a Focus() method that sets the focus on the right part of your control when the control itself gets the focus.
code (for a UserControl containing a textbox that you want to get the focus for instance):
<TextBox x:Class="Test.MyTextBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Button Content="foo" Grid.Column="0" />
<TextBox Name="TextBoxPart" Grid.Column="1" />
</Grid>
</TextBox>
code behind
public partial class MyTextBox : TextBox
{
public static readonly DependencyProperty CaptionProperty =
DependencyProperty.Register("Caption", typeof(string), typeof(MyTextBox), new UIPropertyMetadata(""));
public string Caption
{
get { return (string)GetValue(CaptionProperty); }
set { SetValue(CaptionProperty, value); }
}
public MyTextBox()
{
InitializeComponent();
}
protected override void OnGotFocus(RoutedEventArgs e)
{
TextBoxPart.Focus();
}
}
Edit 2:
I had an issue once, to transfer the focus to a subcontrol in a dataGridCell, and here is what I did in the template:
<ControlTemplate.Triggers>
<Trigger Property="IsFocused" Value="True">
<Setter TargetName="TextBoxPart" Property="FocusManager.FocusedElement" Value="{Binding ElementName=TextBoxPart}" />
</Trigger>
</ControlTemplate.Triggers>
you could try adding this to your template. This should transfer your focus alright.
as for the accessibility, I don't think this will help, but I do not see any way of achieving what you want :-/