/////////////////////////////////////////////////////////////////////////////////////////////////
//
// RegisterStructureChangeListener()
//
// Add a UIA event handler to react to structure change events sent from the browser window.
//
// Runs on the background thread.
//
/////////////////////////////////////////////////////////////////////////////////////////////////
void RegisterStructureChangeListener()
{
// This sample assumes we know which window we want to gets events from.
// *** Note: We must get a pointer to the element we're interested in, in this thread. Do
// not have the UI thread get the element and supply it through to the background thread.
IntPtr hwnd = Win32.FindWindow(strBrowserWindowClass, null);
if (hwnd != IntPtr.Zero)
{
_elementBrowser = _automation.ElementFromHandle(hwnd);
if (_elementBrowser != null)
{
// In general it is not the IEFrame element itself which throws the structure change
// events which we will receive in the handler, but rather various decendants elements.
// It is these descendants which are the "senders" in the event handler later.
// AddStructureChangedEventHandler() can take a cache request as other UIA methods do.
// So if an event handler wanted to retrieve properties from the event sender without
// having to incur the time cost for a cross-proc call, it would use a cache request
// here. (For this sample, the event handler doesn't need that.)
// Other types of UIA event handler can be set up with the following calls:
// AddFocusChangeEventHandler()
// AddAutomationEventHandler()
// AddPropertyChangeEventHandler() - note that some providers might not raise all
// the expected propety change events.
_automation.AddStructureChangedEventHandler(_elementBrowser, TreeScope.TreeScope_Descendants, null, this);
_fAddedEventHandler = true;
}
}
}
public override void Init()
{
IUIAutomation uia = this.IUIAutomation;
if (uia != null)
{
uia.AddStructureChangedEventHandler(this.Element, this.Scope, null, this);
this.IsHooked = true;
}
}
