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POC# - WebBrowser control seems to cache screenshots
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copied!<p>I'm using the WebBrowser control in an ASP.NET MVC 2 app (don't judge, I'm doing it in an admin section only to be used by me), here's the code:</p> <pre><code>public static class Screenshot { private static string _url; private static int _width; private static byte[] _bytes; public static byte[] Get(string url) { // This method gets a screenshot of the webpage // rendered at its full size (height and width) return Get(url, 50); } public static byte[] Get(string url, int width) { //set properties. _url = url; _width = width; //start screen scraper. var webBrowseThread = new Thread(new ThreadStart(TakeScreenshot)); webBrowseThread.SetApartmentState(ApartmentState.STA); webBrowseThread.Start(); //check every second if it got the screenshot yet. //i know, the thread sleep is terrible, but it's the secure section, don't judge... int numChecks = 20; for (int k = 0; k < numChecks; k++) { Thread.Sleep(1000); if (_bytes != null) { return _bytes; } } return null; } private static void TakeScreenshot() { try { //load the webpage into a WebBrowser control. using (WebBrowser wb = new WebBrowser()) { wb.ScrollBarsEnabled = false; wb.ScriptErrorsSuppressed = true; wb.Navigate(_url); while (wb.ReadyState != WebBrowserReadyState.Complete) { Application.DoEvents(); } //set the size of the WebBrowser control. //take Screenshot of the web pages full width. wb.Width = wb.Document.Body.ScrollRectangle.Width; //take Screenshot of the web pages full height. wb.Height = wb.Document.Body.ScrollRectangle.Height; //get a Bitmap representation of the webpage as it's rendered in the WebBrowser control. var bitmap = new Bitmap(wb.Width, wb.Height); wb.DrawToBitmap(bitmap, new Rectangle(0, 0, wb.Width, wb.Height)); //resize. var height = _width * (bitmap.Height / bitmap.Width); var thumbnail = bitmap.GetThumbnailImage(_width, height, null, IntPtr.Zero); //convert to byte array. var ms = new MemoryStream(); thumbnail.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); _bytes = ms.ToArray(); } } catch(Exception exc) {//TODO: why did screenshot fail? string message = exc.Message; } } </code></pre> <p>This works fine for the first screenshot that I take, however if I try to take subsequent screenshots of different URL's, it saves screenshots of the first url for the new url, or sometimes it'll save the screenshot from 3 or 4 url's ago. I'm creating a new instance of WebBrowser for each screenshot and am disposing of it properly with the "using" block, any idea why it's behaving this way?</p> <p>Thanks, Justin</p>

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