delphi twebbrowser modify html before loaded

Question

Is is possible to modify the html before it is loaded/executed in the browser?

To add functions to a web site out of my control I want to change a javascript from the original to my own.

E.g: in the html the browser load I would like to change:

<script src="/java.js" type="text/javascript"></script>  
to:
<script src="http://mysite/java.js" type="text/javascript"></script>

I can not just load my own page as I need to login to the site for it to work and the site use cookies to check im logged in.

I load the modifyed code like this:

Var
  aStream     : TMemoryStream;

begin

if Assigned(WebBrowser1.Document) then 
begin       
aStream := TMemoryStream.Create;

try
     aStream.LoadFromFile(Root + 'main.htm');
     aStream.Seek(0, soFromBeginning);
     (WebBrowser1.Document as IPersistStreamInit).Load(TStreamAdapter.Create(aStream));
  finally
     aStream.Free;
     Timer1.Enabled := True;
  end;
  HTMLWindow2 := (WebBrowser1.Document as IHTMLDocument2).parentWindow;
end;

This used to work, but the site added a login and now the requests the javascript do get access denied. I have tried to navigate to the login and login before I load my own code, but I still get access denied.

Which platform? VCL/FM, also which version of Delphi do you have? — Graymatter, Jun 01 '14 at 00:39

Remy Lebeau · Answer 1 · 2014-06-01T02:35:01.467

1

In VCL, yes. You can download the HTML yourself and modify it as needed (you need to insert a <base href> tag specifying the original URL into the <head> if the HTML contains relative links). Then navigate the browser to about:blank, query its Document for the IPersistStreamInit interface, and call its load() method, passing it the modified HTML using the VCL's TStringStream and TStreamAdapter classes.

In FMX, I have no clue.

edited Jun 01 '14 at 02:35

answered Jun 01 '14 at 02:24

Remy Lebeau

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Added to the first post. – FrankJensen Jun 01 '14 at 14:30
@remy , can you please provide more detailed instructions about how to do it ? I saved the modified html and called it with navigate method, but the page loads without it CSS styles. – delphirules Dec 09 '15 at 13:04
@delphirules: There are plenty of online forum ports and tutorials on how to load HTML data into `TWebBrowser` via `IPersistStreamInit`, if you look around. Does the HTML refer to CSS using an external file (and if so, does it use an absolute or relative URL to refer to that file)? Or is the CSS in the HTML itself? – Remy Lebeau Dec 09 '15 at 18:49

stanleyxu2005 · Answer 2 · 2014-06-02T04:34:13.730

0

Here is the approach:

Create a pluggable MIME filter (refer to IInternetProtocol) to monitor HTML document (mime type text/html) before it is rendered by TWebBrowser.
Use regular expression to replace desired contents. In your case is to replace src="/java.js" with src="http://mysite/java.js".

Here is a code example. And I highly suggest you read these documents first.

edited Jun 02 '14 at 04:34

answered Jun 01 '14 at 18:25

stanleyxu2005

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I removed the previous answer of using `IDocHostUIHandler.TranslateURL`, because I think it might mislead other readers, if they are in a similar situation. – stanleyxu2005 Jun 01 '14 at 18:27
Thanks. I will look in to this, seems like the right approch. – FrankJensen Jun 02 '14 at 09:54

score 0 · Answer 3 · answered Jun 02 '14 at 09:53

For now the problem are solved by adding another twebbrowser to the project. (On a new tab). This webbrowser handle the login and keep the required php session alive. (It is automatic keept alive as long as the window stay open). Now Im able to load my own modifyed code without access denied.

Thanks for all your help.

delphi twebbrowser modify html before loaded

3 Answers3