Does anybody know how to programmatically detect the presence of a 'pdf' 
reader on a user's computer using Delphi?

We were thinking of searching for the presence of an Acrobat Reader 
executable but this method would exclude people using a different reader.

We also were thinking of searching the Registry for the '.pdf' key. But does 
its presence guarantee the presence of a reader?

On Tue, 10 Mar 2009 13:24:38 -0700, John Smith wrote:

> We also were thinking of searching the Registry for the '.pdf' key. But does 
> its presence guarantee the presence of a reader?

It implies that there was once one (or a pdf editor or something else
that has a pdf extension), it doesn't guarantee that it still is, you
could follow the registry keys through and check if the file exists.

-- 
Marc Rohloff [TeamB]
marc -at- marc rohloff -dot- com

> Does anybody know how to programmatically detect the presence of a 'pdf' 
> reader on a user's computer using Delphi?
>
> We were thinking of searching for the presence of an Acrobat Reader 
> executable but this method would exclude people using a different reader.
>
> We also were thinking of searching the Registry for the '.pdf' key. But 
> does its presence guarantee the presence of a reader?

It is pretty much a given than there will be something on every PC
for reading PDF files. Why not just call ShellExecute on the PDF file,
and let windows figure out which program to open?

cheers,

Chris

"Marc Rohloff" <marc@nospam.marcrohloff.com> wrote in message 
news:91062@forums.codegear.com...
> On Tue, 10 Mar 2009 13:24:38 -0700, John Smith wrote:
>
>> We also were thinking of searching the Registry for the '.pdf' key. But 
>> does
>> its presence guarantee the presence of a reader?
>
> It implies that there was once one (or a pdf editor or something else
> that has a pdf extension), it doesn't guarantee that it still is, you
> could follow the registry keys through and check if the file exists.
>

Thanks. I'll do just that.

> -- 
> Marc Rohloff [TeamB]
> marc -at- marc rohloff -dot- com

"Chris Morgan" <chrisXXX at lynxinfo.co.uk> wrote in message 
news:91064@forums.codegear.com...
>> Does anybody know how to programmatically detect the presence of a 'pdf' 
>> reader on a user's computer using Delphi?
>>
>> We were thinking of searching for the presence of an Acrobat Reader 
>> executable but this method would exclude people using a different reader.
>>
>> We also were thinking of searching the Registry for the '.pdf' key. But 
>> does its presence guarantee the presence of a reader?
>
> It is pretty much a given than there will be something on every PC
> for reading PDF files. Why not just call ShellExecute on the PDF file,
> and let windows figure out which program to open?
>

I agree but it's not my call. The boss wants the user to be forewarned if 
the 'pdf' reader is missing.

> cheers,
>
> Chris

"John Smith" <jbrown@nomail.com> wrote in message 
news:91078@forums.codegear.com...

> I agree but it's not my call. The boss wants the user to be
> forewarned if the 'pdf' reader is missing.

ShellExecute() will return an error code that you can check for if a 
suitable reader could not be started.

-- 
Remy Lebeau (TeamB)

John Smith wrote:
> Does anybody know how to programmatically detect the presence of a 'pdf' 
> reader on a user's computer using Delphi?
> 
> We were thinking of searching for the presence of an Acrobat Reader 
> executable but this method would exclude people using a different reader.
> 
> We also were thinking of searching the Registry for the '.pdf' key. But does 
> its presence guarantee the presence of a reader?


There is the FindExecutable API function.

See example at:
http://www.swissdelphicenter.ch/torry/showcode.php?id=103


-- 
Michael Justin
SCJP, SCJA
betasoft - Software for Delphi™ and for the Java™ platform
http://www.mikejustin.com - http://www.betabeans.de

On Tue, 10 Mar 2009 22:49:33 -0700, Michael Justin wrote:

> There is the FindExecutable API function.
> 
> See example at:
> http://www.swissdelphicenter.ch/torry/showcode.php?id=103

You could also call ExtractIconEx which is a bit of a hack but would
check if the file exists.

-- 
Marc Rohloff [TeamB]
marc -at- marc rohloff -dot- com

> Does anybody know how to programmatically detect the presence of a 'pdf' 
> reader on a user's computer using Delphi?
>
> We were thinking of searching for the presence of an Acrobat Reader 
> executable but this method would exclude people using a different reader.
>
> We also were thinking of searching the Registry for the '.pdf' key. But 
> does its presence guarantee the presence of a reader?

You can also do this:

function IsPDFReaderAvail: Boolean;
var
  RegKey: TRegistry;
  AssocAppInfo: string;
  Extension, ExtractPath, ExtractFN: String;
begin
  Result := False;
  Extension := '.pdf';
  try
    RegKey := TRegistry.Create(KEY_QUERY_VALUE);
  except
    Exit;
  end;

  RegKey.RootKey := HKEY_CLASSES_ROOT;
  if RegKey.OpenKeyReadOnly(Extension) then
  begin {extension key exists?}
    try
      AssocAppInfo := RegKey.ReadString(''); {read app key}
      RegKey.CloseKey;
    except
      RegKey.Free;
      Exit;
    end;
  end;
  if ((AssocAppInfo <> '') and (RegKey.OpenKeyReadOnly(AssocAppInfo + 
'\Shell\Open\Command'))) then
  begin
    try
      ExtractPath     := Trim(StringReplace(RegKey.ReadString(''), '"', '', 
[rfReplaceAll]));
      ExtractFN       := Trim(StringReplace(ExtractPath, '%1', '', 
[rfReplaceAll]));
      ExtractPath     := ExtractFilePath(ExtractPath);
      ExtractFN       := ExtractFileName(ExtractFN);
      Result          := FileExists(ExtractPath + ExtractFN);
      RegKey.CloseKey;
    except
      RegKey.Free;
      Exit;
    end;
  end;
end;

Following is the sample code in [VB.NET]
 
'--Declaration
Public Declare Auto Function FindExecutable Lib "shell32.dll" (ByVal lpFile As String, ByVal lpDirectory As String, ByVal lpResult As String) As Int32
 
'--
Dim intRetval As Integer = FindExecutable(PDF FILE FULL PATH NAME, "", "")

If intRetval  < =  32

 MessageBox.Show("The Adobe Reader, which is required to view this file, may not be correctly installed.", "Adobe Reader Not found", MessageBoxButtons.OK,    MessageBoxIcon.Exclamation)

End if

For more information  [http://www.mindfiresolutions.com/FindExecutable-API-569.php]

<Eliza Sahoo> wrote in message news:240304@forums.embarcadero.com...
> Following is the sample code in [VB.NET]

FindExecutable() is a Win32 API function, and as such works exactly the same 
way in Delphi, ie:

{code:delphi}
uses
  ..., ShellAPI;

var
  intRetval: Integer;
begin
  intRetval := FindExecutable(PChar(PDF FILE FULL PATH NAME), '', '');
  if intRetval  <= 32 then
    Application.MessageBox('The Adobe Reader, which is required to view this 
file, may not be correctly installed.', 'Adobe Reader Not found', MB_OK or 
MB_ICONEXCLAMATION);
end;
{code}

-- 
Remy Lebeau (TeamB)

Eliza Sahoo wrote:
> Following is the sample code in [VB.NET]
>  
> '--Declaration
> Public Declare Auto Function FindExecutable Lib "shell32.dll" (ByVal lpFile As String, ByVal lpDirectory As String, ByVal lpResult As String) As Int32
>  
> '--
> Dim intRetval As Integer = FindExecutable(PDF FILE FULL PATH NAME, "", "")
> 
> If intRetval  < =  32
> 
>  MessageBox.Show("The Adobe Reader, which is required to view this file, may not be correctly installed.", "Adobe Reader Not found", MessageBoxButtons.OK,    MessageBoxIcon.Exclamation)
> 
> End if
> 
> For more information  [http://www.mindfiresolutions.com/FindExecutable-API-569.php]

If that were on my box, it would be wrong because I don't use Adobe for a PDF reader.....
Mike

> If that were on my box, it would be wrong because I don't use Adobe
> for a PDF reader.....  Mike

Not really (and this is coming from a Foxit user...). The only Adobe
Reader-specific thing is the message box text, which only gets shown
when there's no associated EXE for PDF files at all.

Chris Rolliston wrote:
>> If that were on my box, it would be wrong because I don't use Adobe
>> for a PDF reader.....  Mike
> 
> Not really (and this is coming from a Foxit user...). The only Adobe
> Reader-specific thing is the message box text, which only gets shown
> when there's no associated EXE for PDF files at all.

Yep, that's what I meant.

> {quote:title=John Smith wrote:}{quote}
> Does anybody know how to programmatically detect the presence of a 'pdf' 
> reader on a user's computer using Delphi?
> 
> We were thinking of searching for the presence of an Acrobat Reader 
> executable but this method would exclude people using a different reader.
> 
> We also were thinking of searching the Registry for the '.pdf' key. But does 
> its presence guarantee the presence of a reader?

function IsAppOnBoard(const FileExt:string):String;

  function CleanOpenCmd(Cmd:String):String;
    var
      i, j:integer;
    begin
      result:='';
      for i:=1 to length(Cmd) do
        begin
          for j:=i to length(Cmd) do
            begin
              result:=result+Cmd[j];
              if FileExists(Result) then
                begin
                  exit;
                end;
            end;
          result:='';
        end;
    end;

var
  Reg : TRegistry;
  tmp,
  sKey : string;
  AccessMode : Cardinal;
begin
  Result:='';

  sKey := '\Shell\Open\Command';
  AccessMode := GetRegAccessMode(sKey);

  Reg:=TRegistry.Create(AccessMode);

    try
       Reg.RootKey:=HKEY_CLASSES_ROOT;

         if Reg.OpenKeyReadOnly(FileExt) then
          begin
            tmp:=Reg.ReadString('');
            Reg.CloseKey;
                if Reg.OpenKeyReadOnly(tmp+sKey) then
                  begin
                    tmp:=Reg.ReadString('');
                    Reg.CloseKey;
                    Result:=CleanOpenCmd(tmp);
                  end;
          end;
    finally
      Reg.Free;
    end;
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  showmessage(IsAppOnBoard('.pdf'));
end;


Will work also:

IsAppOnBoard('.doc')
IsAppOnBoard('.zip')

and so on
 


All the best

Axel

Edited by: Alexander Lang on May 10, 2010 10:41 AM

<Alexander Lang> wrote in message news:241189@forums.embarcadero.com...

>  function CleanOpenCmd(Cmd:String):String;

The default verb for any file type is not always "open".  You have to read 
the Registry to see if there is an overriding verb, and then fallback to 
"open" as a last resort.

-- 
Remy Lebeau (TeamB)

Alexander Lang wrote:
> John Smith wrote:
>> Does anybody know how to programmatically detect the presence of a 'pdf' 
>> reader on a user's computer using Delphi?
>>
>> We were thinking of searching for the presence of an Acrobat Reader 
>> executable but this method would exclude people using a different reader.
>>
>> We also were thinking of searching the Registry for the '.pdf' key. But does 
>> its presence guarantee the presence of a reader?
> 
> function IsAppOnBoard(const FileExt:string):String;

This function's name suggests it returns a yes/no answer, not a string.

>   function CleanOpenCmd(Cmd:String):String;
>     var
>       i, j:integer;
>     begin
>       result:='';
>       for i:=1 to length(Cmd) do
>         begin
>           for j:=i to length(Cmd) do
>             begin
>               result:=result+Cmd[j];
>               if FileExists(Result) then
>                 begin
>                   exit;
>                 end;
>             end;
>           result:='';
>         end;
>     end;

If the registry value is the non-existent file name "C:\Does not 
exist\foo.exe" and there's a file in the process's current directory 
named "C", this code will return that file as the command. Is that what 
you intended?

Or, if I have a directory on my computer named "C:\Does" then this 
function will return that directory name as the command.

It likes like you meant to mimic the behavior CreateProcess uses when a 
command line isn't quoted.

-- 
Rob

> {quote:title=Rob Kennedy wrote:}{quote}
> Alexander Lang wrote:
> > John Smith wrote:
> >> Does anybody know how to programmatically detect the presence of a 'pdf' 
> >> reader on a user's computer using Delphi?
> >>
> >> We were thinking of searching for the presence of an Acrobat Reader 
> >> executable but this method would exclude people using a different reader.
> >>
> >> We also were thinking of searching the Registry for the '.pdf' key. But does 
> >> its presence guarantee the presence of a reader?
> > 
> > function IsAppOnBoard(const FileExt:string):String;
> 
> This function's name suggests it returns a yes/no answer, not a string.
> 
> >   function CleanOpenCmd(Cmd:String):String;
> >     var
> >       i, j:integer;
> >     begin
> >       result:='';
> >       for i:=1 to length(Cmd) do
> >         begin
> >           for j:=i to length(Cmd) do
> >             begin
> >               result:=result+Cmd[j];
> >               if FileExists(Result) then
> >                 begin
> >                   exit;
> >                 end;
> >             end;
> >           result:='';
> >         end;
> >     end;
> 
> If the registry value is the non-existent file name "C:\Does not 
> exist\foo.exe" and there's a file in the process's current directory 
> named "C", this code will return that file as the command. Is that what 
> you intended?
> 
> Or, if I have a directory on my computer named "C:\Does" then this 
> function will return that directory name as the command.
> 
> It likes like you meant to mimic the behavior CreateProcess uses when a 
> command line isn't quoted.
> 
> -- 
> Rob

Hello Rob,

ups i forget something ;-). 


Here is the unit, test it and you will see what happens.

All the best Alexander

<pre>
unit main;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
   private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

const
  KEY_WOW64_64KEY = $0100;
  KEY_WOW64_32KEY = $0200;

var
  Form1: TForm1;


implementation

uses
  Registry;

{$R *.dfm}

function IsWow64: Boolean;
type
  TIsWow64Process = function( // Type of IsWow64Process API fn
    Handle: Windows.THandle; var Res: Windows.BOOL
  ): Windows.BOOL; stdcall;
var
  IsWow64Result: Windows.BOOL;      // Result from IsWow64Process
  IsWow64Process: TIsWow64Process;  // IsWow64Process fn reference
begin
  // Try to load required function from kernel32
  IsWow64Process := Windows.GetProcAddress(
    Windows.GetModuleHandle('kernel32'), 'IsWow64Process'
  );
  if Assigned(IsWow64Process) then
  begin
    // Function is implemented: call it
    if not IsWow64Process(
      Windows.GetCurrentProcess, IsWow64Result
    ) then
      raise SysUtils.Exception.Create('IsWow64: bad process handle');
    // Return result of function
    Result := IsWow64Result;
  end
  else
    // Function not implemented: can't be running on Wow64
    Result := False;
end;

function GetRegAccessMode(sOrtID: String): Cardinal;
begin
  // 32-Bit-Windows
  if not IsWow64 then begin
    Result := KEY_ALL_ACCESS;
    exit;
  end;
  // 64-Bit-Windows
 if Pos('Wow6432Node', sOrtID) > 0 then // 32-Bit-Wert schreiben?
    begin
    result := (KEY_ALL_ACCESS OR KEY_WOW64_32KEY);
   // ShowMessage('KEY_WOW64_32KEY' +#13+sOrtID)
    end
  else
    begin
    result := (KEY_ALL_ACCESS OR KEY_WOW64_64KEY);
   // ShowMessage('KEY_WOW64_64KEY' +#13+sOrtID)
    end;
end;

// Ermittelt die Anwendung mit der standardgemäß die Dateien verknüpft sind.
function IsAppOnBoard(const FileExt:string):String;

  function CleanOpenCmd(Cmd:String):String;
    var
      i, j:integer;
    begin
      result:='';
      for i:=1 to length(Cmd) do
        begin
          for j:=i to length(Cmd) do
            begin
              result:=result+Cmd[j];
              if FileExists(Result) then
                begin
                  exit;
                end;
            end;
          result:='';
        end;
    end;

var
  Reg : TRegistry;
  tmp,
  sKey : string;
  AccessMode : Cardinal;
begin
  Result:='';
  sKey := '\Shell\Open\Command';
  AccessMode := GetRegAccessMode(sKey);

  Reg:=TRegistry.Create(AccessMode);

    try
       Reg.RootKey:=HKEY_CLASSES_ROOT;

         if Reg.OpenKeyReadOnly(FileExt) then
          begin
            tmp:=Reg.ReadString('');
            Reg.CloseKey;
                if Reg.OpenKeyReadOnly(tmp+sKey) then
                  begin
                    tmp:=Reg.ReadString('');
                    Reg.CloseKey;
                    Result:=CleanOpenCmd(tmp);
                  end;
          end;
    finally
      Reg.Free;
    end;
end;

// Beispiel
procedure TForm1.Button1Click(Sender: TObject);
begin
  // open PDF with parameters e.g. ShellExecute(),  see:
 // http://partners.adobe.com/public/developer/en/acrobat/PDFOpenParameters.pdf#page=5

  showmessage(IsAppOnBoard('.pdf'));
end;

end.
</pre>

Edited by: Alexander Lang on May 14, 2010 7:07 AM