Querying the DOM

[emerick]

I often have a need to query the DOM and return some data. While CEF makes this doable, it's a lot of work. I was wondering if a convenience method like the following is technically feasible:

Code: Select all

 
///
// Query the DOM document.
///
/*--cef()--*/
virtual void QueryDOM(CefRefPtr<CefDOMVisitor> domVisitor, CefRefPtr<CefStringVisitor> strVisitor) =0;


This would run from the browser process. Implementation would look similar to GetText, where the visitors are wrapped in CefResponseManager::Handler and then the command is sent to the render process. The renderer process would call domVisitor->VisitDOM(strVisitor) and the implementation of VisitDOM would call strVisitor->Visit() with the contents to return.

Does that seem reasonable or have I missed something that would prevent this? If it's feasible, I may take a run at it if we think it's something that would be generally useful/desirable.

[magreenblatt]

You can implement something like this in your client application. Keep in mind that the result may be out of date by the time it arrives back in the browser process.

[emerick]

Right, good point about it potentially being out of date by the time it arrives back. Well, good to know that this is at least technically feasible - thanks Marshall!

[tgraupmann]

A code sample would be awesome...

Code: Select all

private sealed class SourceVisitor : CefStringVisitor
        {
            private readonly Action<string> _callback;

            public SourceVisitor(Action<string> callback)
            {
                _callback = callback;
            }

            protected override void Visit(string value)
            {
                _callback(value);
            }
        }


This works...

Code: Select all

browser.LoadingStateChanged += (s, e) =>
                {
                    CefBrowser b = ((Xilium.CefGlue.Demo.Browser.WebBrowser)s).CefBrowser;
                    string[] names = b.GetFrameNames();
                    foreach (string name in names)
                    {
                        CefFrame frame = b.GetFrame(name);
                        if (null != frame)
                        {
                            CefStringVisitor visitor = new SourceVisitor((text) =>
                            {
                                if (!string.IsNullOrEmpty(text))
                                {

                                }
                            });
                            frame.GetSource(visitor);
                        }
                    }