Regarding udione's solution to the WebBrowser memory leak

Question

This code was given by udione in response to the perennial question about the memory leak in the WebBrowser control in .Net.

//dispose to clear most of the references 
this.webbrowser.Dispose(); 
BindingOperations.ClearAllBindings(this.webbrowser); 

//using reflection to remove one reference that was not removed with the dispose  
var field = typeof(System.Windows.Window).GetField("_swh", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance); 

var valueSwh = field.GetValue(mainwindow); 

var valueSourceWindow = valueSwh.GetType().GetField("_sourceWindow", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).GetValue(valueSwh); 

var valuekeyboardInput = valueSourceWindow.GetType().GetField("_keyboardInputSinkChildren", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).GetValue(valueSourceWindow); 

System.Collections.IList ilist = valuekeyboardInput as System.Collections.IList; 

lock(ilist) 
{ 
    for (int i = ilist.Count-1; i >= 0; i--) 
    { 
        var entry = ilist[i]; 
        var sinkObject = entry.GetType().GetField("_sink", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance); 
        if (object.ReferenceEquals(sinkObject.GetValue(entry), this.webbrowser.webBrowser)) 
        { 
            ilist.Remove(entry); 
        } 
    } 
}

1) That third line,

BindingOperations.ClearAllBindings(this.webbrowser);

won't compile for me. What is the type of this.webbrowser? I had assumed it was WebBrowser, but the method requires System.Windows.DependencyObject.

2) In the line

var valueSwh = field.GetValue(mainwindow);

what is mainwindow? The form holding the browser control?

3) In the sixth line from the bottom,

if (object.ReferenceEquals(sinkObject.GetValue(entry), this.webbrowser.webBrowser))

what is the type of this.webbrowser.webBrowser? I see no field called webBrowser in the WebBrowser type. Is this just a typo?

Thanks for any help.

score 1 · Answer 1 · answered Mar 13 '13 at 00:49

BindingOperations is for WPF - you won't need this line if you are using WinForms.
To get the mainwindow, you just need to call the WPF method GetWindow.

 var mainwindow = GetWindow(this);

3.this.webbrowser is the control ID of the WPF control (FrameworkElement.Name). By default, this is usually webbrowser1.

Regarding udione's solution to the WebBrowser memory leak

1 Answers1