[DUG] ShellExecute encoding

[John Bird]

I solved this - in case its of interest here's how I did it.

The file URL is encoded by the browser if it does not already start with 
file:/// and have only "/" characters rather than "\" in it.   In order to 
pass a file URL to ShellExecute with a Tag in it, one cannot therefore just 
execute the html file which is the normal way, but instead execute the 
default browser and pass the ready URL to it

Here is the code I used, note the routine can be used to get the program to 
execute any extension.  In my case it allows me to send a url like

C:\HelpDir\HelpFile.HTM#TAGNAME and the browser will get the correct URL and 
position on the page at that tag.

//pass aTag as tagname to jump to in web page WITHOUT the # before it
//have to use this rather than doing ShellExecute on the help file directly 
as the browser
//will re-encode the URL including turning the # into a %23 unless the 
format is already correct
procedure xcOpenHTMLFile(aURL:string;aTag:string);
var
lparams:string;
i:integer;
sExe:string;
begin
  lparams:=aURL+'#'+aTag;   //#
  for I := 1 to length(lparams) do
    if lparams[i]='\' then lparams[i]:='/';
  lparams:='file:///'+lparams;      //puts argument into encoding form the 
browser expects
   sEXE:=xfGetExeByExtension('.htm') ;
   if (sEXE <> '') and FileExists(sEXE) then
     ShellExecute(Application.Mainform.Handle,'OPEN', PChar(sEXE), 
PCHar(lparams), nil, SW_SHOWNORMAL) ;
end;

//from http://delphi.about.com/cs/adptips2003/a/bltip0103_3.htm
function xfGetExeByExtension(sExt : string) : string;
var
   sExtDesc:string;
begin
   with TRegistry.Create do
   begin
     try
       RootKey:=HKEY_CLASSES_ROOT;
       if OpenKeyReadOnly(sExt) then
       begin
         sExtDesc:=ReadString('') ;
         CloseKey;
       end;
       if sExtDesc <>'' then
       begin
         if OpenKeyReadOnly(sExtDesc + '\Shell\Open\Command') then
         begin
           Result:= ReadString('') ;
         end
       end;
     finally
       Free;
     end;
   end;

   if Result <> '' then
   begin
     if Result[1] = '"' then
     begin
       Result:=Copy(Result,2,-1 + Pos('"',Copy(Result,2,MaxINt))) ;
     end
   end;
end;


John