TWebBrowser and FEATURE_BROWSER_EMULATION at runtime

Has anyone tried creating and destroying a TWebBrowser at runtime and using FEATURE_BROWSER_EMULATION to switch the 开发者_开发技巧browser mode before re-creating the TWebBrowser to enable switching the mode without restarting the application?

I'm wondering if the setting is only read when starting the app, or when the web browser control is created.

You don't need to create or destroy a TEmbeddedWB yourself. I made this (see below) to set the correct IE version for an app. Works perfecctly. You must do this before the form is created. You can do this in a initialization statement, for example:

 TIEMode = (iemUnknown, iemIE7, iemIE8, iemIE9, iemIE10);
 // iemUnknown, don't use this as parameter, return result only
 // iemIE10: To run a WebBrowser control in IE10 Standards Mode
 // iemIE9: To run a WebBrowser control in IE9 Standards Mode
 // iemIE8: To run a WebBrowser control in IE8 Standards Mode
 // iemIE7: To run in IE7 Standards Mode

function embeddedWebbrowserMode(bSet : Boolean; Mode: TIEMode; AppName: string = '') : LongInt;
const
  REG_KEY = 'Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION';

var
  Reg: TRegistry;
  Value: LongInt;
  i : LongInt;

begin
  Result:=0;
  if( bSet ) and ( Mode = iemUnknown ) then
   Exit;

  if AppName = '' then
    AppName := ExtractFileName(Application.ExeName);

  if( bSet ) then
   case Mode of
     iemIE7 :  Value := 7000;
     iemIE8 : Value := 8888;
     iemIE9 : Value:=9999;
     else Value:=10001; // IE10 standards mode
   end
  else Value:=0; 

  Reg:=nil;
  try
   Reg := TRegistry.Create();
   Reg.RootKey := HKEY_CURRENT_USER;
    if( Reg.OpenKey(REG_KEY, True) ) then
    begin
      if( bSet ) then
       begin
        Reg.WriteInteger(AppName, Value);
        Result:=Value;
       end
      else Value:=Reg.ReadInteger( AppName );
      Reg.CloseKey;
    end;
  except;
  end;

  if( Assigned( Reg )) then
   FreeAndNil(Reg);

  if( NOT bSet ) and ( Value > 0 ) then
  begin
   i:=Value div 1000;
   if( i >= 7 ) and ( i <= 10 ) then
    begin
        case i of
         7000  : Result:=Byte(iemIE7);
         8888  : Result:=Byte(iemIE8);
         9999  : Result:=Byte(iemIE9);
         10001 : Result:=Byte(iemIE10);
          else begin
                if( i >=10 ) then
                 Result:=Byte(iemIE10);
               end;
        end;
    end;
  end;
end;

function setEmbeddedWebbrowserMode(Mode: TIEMode; AppName: string = '') : boolean;
begin
 Result:=( embeddedWebbrowserMode(TRUE, Mode, AppName ) > 0 ); 
end;

function getEmbeddedWebbrowserMode( AppName: string = '' ) : TIEMode;
begin
 Result:= TIEMode( Byte( embeddedWebbrowserMode(FALSE, iemUnknown, AppName ))); 
end;

Example how to use it:

initialization
 setEmbeddedWebbrowserMode( iemIE9 );

I tried it and it didn't work.

This is what I did:

1. Created and started an application with existing TWebBrowser which a loads web page that displays the current user agent - it displayed MSIE 7.0 (installed is 9.0, so compatibility mode for embedded controls kicked in)
2. While still running I added the application to HKCU\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION to enforce use of version 9 (added 9999 for my exe name)
3. Still running I dynamically created a TWebBrowser and loaded same web page as in step 1 - but user agent still showed MSIE 7.0
4. After restarting the application the user agent was 9.0 from the beginning

So it seems like you would have to restart the application.