C#: Generate WebPage Thumbmail Screenshot Image
There are a few services out there that serve up screenshots of any webpage for you to display on your website. One popular one is Kwiboo; this is the one that DotNetKicks uses. For some time now I’ve wondered what the easiest way to do this in .NET was, and today I stumbled upon the undocumented WebBrowser.DrawToBitmap method that makes this extremely easy to do.
Here’s a sample method that returns a Bitmap representation of a webpage:
public Bitmap GenerateScreenshot(string url)
{
// This method gets a screenshot of the webpage
// rendered at its full size (height and width)
return GenerateScreenshot(url, -1, -1);
}
public Bitmap GenerateScreenshot(string url, int width, int height)
{
// Load the webpage into a WebBrowser control
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
wb.Width = width;
wb.Height = height;
if (width == -1)
{
// Take Screenshot of the web pages full width
wb.Width = wb.Document.Body.ScrollRectangle.Width;
}
if (height == -1)
{
// 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
Bitmap bitmap = new Bitmap(wb.Width, wb.Height);
wb.DrawToBitmap(bitmap, new Rectangle(0, 0, wb.Width, wb.Height));
wb.Dispose();
return bitmap;
}
Here are some example usages of the above method:
// Generate thumbnail of a webpage at 1024x768 resolution
Bitmap thumbnail = GenerateScreenshot("", 1024, 768);
// Generate thumbnail of a webpage at the webpage's full size (height and width)
thumbnail = GenerateScreenshot("");
// Display Thumbnail in PictureBox control
pictureBox1.Image = thumbnail;
/*
// Save Thumbnail to a File
thumbnail.Save("thumbnail.png", System.Drawing.Imaging.ImageFormat.Png);
*/
By the way, I stumbled upon the WebBrowser.DrawToBitmap while taking a look at the source code for the WebPreview
tool over at SmallSharpTools.com.
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