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johnkainn

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convert html string to an image dynamically (continue2)

I want to use following code (see also related question)  to creata dynamically an image from html.
How do I change it so that it works for web application (C#)?


[STAThread()]  << -- attribute
protected void Page_Load(object sender, EventArgs e)
{
 System.Windows.Forms.WebBrowser wb = new System.Windows.Forms.WebBrowser();
      wb.Size = new System.Drawing.Size(1024, 768);
      wb.ScrollBarsEnabled = false;
 
      wb.DocumentCompleted += new System.Windows.Forms.WebBrowserDocumentCompletedEventHandler(delegate(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) {
        System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(wb.ClientRectangle.Width, wb.ClientRectangle.Height);
        wb.DrawToBitmap(bmp, new System.Drawing.Rectangle(0,0, bmp.Width, bmp.Height));
        bmp.Save(@"c:\foo.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
      });
      wb.Navigate(@"file://c:\my.html");
      //wb.Navigate("http://www.google.com"); 
 
}

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Avatar of oobayly
oobayly
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What do you mean by "so that it works"? Are you wanting to use the page to save the image on the webserver, or return the resulting image to the client?

If it's the latter, you could modify the code to write the bitmap to a member variable. Then poll the result until it's valid & write it to the response.

I'd suggest saving local copies of the image, and check for them first. That way you don't have to recreate the image each time.
private Bitmap bmp;
 
[STAThread()]  << -- attribute
protected void Page_Load(object sender, EventArgs e) {
  System.Windows.Forms.WebBrowser wb = new System.Windows.Forms.WebBrowser(); 
  wb.Size = new System.Drawing.Size(1024, 768);
  wb.ScrollBarsEnabled = false;
 
  wb.DocumentCompleted += new System.Windows.Forms.WebBrowserDocumentCompletedEventHandler(delegate(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) {
    bmp = new System.Drawing.Bitmap(wb.ClientRectangle.Width, wb.ClientRectangle.Height);
    wb.DocumentCompleted += new System.Windows.Forms.WebBrowserDocumentCompletedEventHandler(delegate(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) {
      System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(wb.ClientRectangle.Width,  wb.ClientRectangle.Height);
      wb.DrawToBitmap(bmp, new System.Drawing.Rectangle(0,0, bmp.Width, bmp.Height));
  });
  wb.Navigate(@"file://c:\my.html");
 
  // Wait for the download to complete 
  while (bmp == null){
    Thread.Sleep(50);
  }
  
  // Write to a PNG (stream needs to be seekable)
  MemoryStream ms = new MemoryStream();
  bmp.Save(ms, ImageFormat.Png);
  
  // Send the image to the client
  Response.ContentType = "image/png";
  ms.WriteTo(Response.OutputStream);
  
  ms.Dispose();
  bmp.Dispose();
}

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Avatar of johnkainn
johnkainn

ASKER

I want to save the image to a webserver.
I get an error using System.Windows.Forms.WebBrowser
( The type or namespace name 'Windows' does not exist in the namespace 'System' (are you missing an assembly reference?)  )
How should I write it so it works for web application?
I've been trying to get this to work.

The STAThread attribute didn't work for me so I added AspCompat="true" to the Page....

<%@ Page ... AspCompat="true"  %>

And you need to add a reference the System.Windows.Forms

At the moment I can't get the Navigate(url) to trigger anything. I've added event handers to DocumentCompleted, ProgressChanged and StatusTextChanged. non of them fire.

oobayly, your version of the code has nested DocumentCompleted events, is this correct?


		System.Windows.Forms.WebBrowser wb = new System.Windows.Forms.WebBrowser();
		wb.Size = new System.Drawing.Size(1024, 768);
		wb.ScrollBarsEnabled = false;
 
		wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(this.DocumentCompleted);
 
		wb.ProgressChanged += new WebBrowserProgressChangedEventHandler(wb_ProgressChanged);
 
		wb.StatusTextChanged += new EventHandler(wb_StatusTextChanged);
 
		wb.Navigate(url);
 
		// Wait for the download to complete 
		while (this.bmp == null)
			Thread.Sleep(50);
 
 
		// Write to a JPG (stream needs to be seekable)
		MemoryStream ms = new MemoryStream();
		bmp.Save(ms, ImageFormat.Jpeg);
 
		// Send the image to the client
		this.Response.ContentType = "image/jpg";
		ms.WriteTo(this.Response.OutputStream);
 
		ms.Dispose();
		bmp.Dispose();

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SOLUTION
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oobayly
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Thanks. Unfortunately I am getting errors when I try to run this code.

johnkainn,

could you explain what the errors are!
I get following errors:
1)  Error    18    The type or namespace name 'Windows' does not exist in the namespace 'System' (are you missing an assembly reference?)

2) Error    17    The name 'WebBrowserReadyState' does not exist in the current context    

3) Error    16    The type or namespace name 'Uri' could not be found (are you missing a using directive or an assembly reference?)    

4) Error    15    The type or namespace name 'WebBrowser' could not be found (are you missing a using directive or an assembly reference?)    






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