private static void OnSuppressEraseBackgroundChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is WebBrowser)
{
WebBrowser webBrowser = (WebBrowser)d;
bool newValue = (bool)e.NewValue;
if (newValue)
{
if (!TryHookWebBrowser(webBrowser))
{
// The IE window has not been created yet, so we'll
// look for it once a web page has been loaded.
webBrowser.LoadCompleted += new LoadCompletedEventHandler(WebBrowserLoadCompleted);
}
}
else
{
// When no longer suppressing the WM_ERASEBKGND message,
// dispose our window hook.
IEWindowHook hook = (IEWindowHook)webBrowser.GetValue(SuppressEraseBackgroundWindowHookProperty);
if (hook != null)
{
hook.Dispose();
}
webBrowser.ClearValue(SuppressEraseBackgroundWindowHookProperty);
}
}
}
private static bool TryHookWebBrowser(WebBrowser webBrowser)
{
if (GetSuppressEraseBackground(webBrowser))
{
// Try to find the IE window several layers within the WebBrowser.
IntPtr hwndIEWindow = GetIEWindow(webBrowser);
if (hwndIEWindow != IntPtr.Zero)
{
// Hook the window messages so we can intercept the
// WM_ERASEBKGND message.
IEWindowHook hook = new IEWindowHook(new HWND(hwndIEWindow));
// Keep our hook alive.
webBrowser.SetValue(SuppressEraseBackgroundWindowHookProperty, hook);
return(true);
}
}
return(false);
}
private static bool TryHookWebBrowser(WebBrowser webBrowser)
{
if (GetSuppressEraseBackground(webBrowser))
{
// Try to find the IE window several layers within the WebBrowser.
IntPtr hwndIEWindow = GetIEWindow(webBrowser);
if (hwndIEWindow != IntPtr.Zero)
{
// Hook the window messages so we can intercept the
// WM_ERASEBKGND message.
IEWindowHook hook = new IEWindowHook(new HWND(hwndIEWindow));
// Keep our hook alive.
webBrowser.SetValue(SuppressEraseBackgroundWindowHookProperty, hook);
return true;
}
}
return false;
}
