System.Windows.Automation is EXTREMELY slow.
System.Windows.Automation is full of bugs. It may not return all children of an AutomationElement, which is a very severe bug.
Apart from that the implementation is not thread safe.
System.Windows.Automation is deprecated. Do not use it!
In the MSDN you find the following note:
UI Automation was first available in Windows XP as part of the
Microsoft .NET Framework. Although an unmanaged C++ API was also
published at that time, the usefulness of client functions was limited
because of interoperability issues. For Windows 7, the API has been
rewritten in the Component Object Model (COM).
Although the library functions introduced in the earlier version of
UI Automation are still documented, they should not be used in new
applications.
The solution to slow performance is to use the new IUIAutomationElement COM interface instead of the old System.Windows.Automation C# interface. After that the code will be running lightning fast!
Apart from that the new interface offers much more patterns and Microsoft is extending it continously. In the Windows 10 SDK (UIAutomationClient.h and UIAutomationCore.h) several patterns and properties have been added which are not available in the .NET Automation framework.
The following patterns are available in the COM version of UIAutomation which do not exist in System.Windows.Automation:
- IUIAutomationLegacyIAccessiblePattern
- IUIAutomationObjectModelPattern
- IUIAutomationAnnotationPattern
- IUIAutomationTextPattern2
- IUIAutomationStylesPattern
- IUIAutomationSpreadsheetPattern
- IUIAutomationSpreadsheetItemPattern
- IUIAutomationTransformPattern2
- IUIAutomationTextChildPattern
- IUIAutomationDragPattern
- IUIAutomationDropTargetPattern
- IUIAutomationTextEditPattern
- IUIAutomationCustomNavigationPattern
Additionally the following Control types have been added:
- AppBar
- SemanticZoom
Additionally the following Element’s have been added:
- IUIAutomationElement2
- IUIAutomationElement3
- IUIAutomationElement4
And what concerns the bugs: The new COM UIAutomation Framework is very well designed and I could not find bugs on the client side of the framework which is a great progress compared to System.Windows.Automation. But several missing features and even bugs on the server side of the framework. On the server side each GUI framework must implement an UIAutomation provider (see MSDN: Interfaces for Providers). So these problems differ depending on what type of application you are automating because each GUI framework has it’s own problems:
In the Native Windows GUI features are missing: Lots of controls do not implement the patterns that they should implement. For example a SplitButton in a native Toolbar should implement the Invoke pattern to click the button and the ExpandCollapse pattern to open the drop-down menu. But the ExpandCollapse pattern is missing which makes it difficult to use SplitButtons. If you obtain a Toolbar SplitButton by IUIAutomation->ElementFromPoint() and then ask for it’s parent you will get a crippled element. And the Pager control cannot be automated at all.
Also in WPF applications there are controls that are implemented buggy by Microsoft: For example if you have a Calendar control you see two buttons at the top to switch to the next/previous month. If you execute the Invoke pattern on these buttons you will get an UIA_E_NOTSUPPORTED error. But this is not a bug on the client side of the framework, because for other buttons the Invoke pattern works correctly. This is a bug in the WPF Automation server. And if you test IUIAutomationTextRange with a WPF RichTextBox, you will find that several commands are not implemented: Select() and ScrollIntoView() do simply nothing.
For .NET Forms applications Microsoft did not make much effort to support them. The .NET Calendar control cannot be automated at all. The entire control is not even recognized as Calendar. It has the ControlType “Pane” with no child elements in it. The same applies to the DateTimePicker. And for complex controls like DataGrid and PropertyGrid the only implemented pattern is LegacyIAccessible which is a poor support. These controls should implement at least the Table and the Grid and the ScrollItem pattern.
Also Internet Explorer cannot be automated because elements outside the visible area cannot be scrolled automatically into view due to missing coordinates. (The Bounds are returned as an empty rectangle) And the ScrollItem pattern is not implemented. (Yes, I know that Internet Explorer has been replaced with Edge in Windows 10, but the UIAutomation framework exists since Windows 7 and Microsoft did not implement a usefull automation support in Internet Explorer in all these years)
I saw even complete crashes of the automated application. For example Visual Studio and TotalCommander will crash if you execute certain automation commands on a certain control. Here – once again – the bug lies in the server side implementation of the framework.
Summary: We have a great framework with limited usefullness. The Microsoft team that developed the new UIAutomation framework did a great job, but the other areas in Microsoft (the native GUI, WPF, .NET and Internet Explorer team) do not support this framework. This is very sad because only a small effort would have to be made to offer a better functionality. But it seems that the users who use UIAutomation in the first place (handicapped people) are not a profitable market.