How to reliably launch an application?

[David Rose]

Hi,

I am trying to launch pdf files (in this case). The test application takes
the path to the pdf from a TextBox when the user clicks a button. I have
written code that works on my computer, but I have doubts that my method is
universal.

Basically, in HKEY_CLASSES_RO OT, I look up the .pdf extension and get the
human readable class id. Then I look that up, recursing through the tree
until I get to "command" and then return that value. This seems to work for
the Adobe Acrobat Reader...

There must be some general method that Windows uses to find the application
when the user double clicks on a file. Or, is there something in the .NET
Framework to accomplish this?

Here is my code:

private void OnViewFileClick (object sender, System.EventArg s e)
{
string fName = tbFile.Text.Tri m();

if ( !File.Exists(fN ame) )
{
MessageBox.Show (this, "File " + fName + " does not exist", "File IO
Error");
return;
}

string ReaderPath = String.Empty;
try
{
RegistryKey key = Registry.Classe sRoot;
RegistryKey keyPDF = key.OpenSubKey( ".pdf", false);
string [] classNames = keyPDF.GetSubKe yNames();

if ( classNames == null )
{
MessageBox.Show (this, "No application associated with the .pdf
extension");
return;
}

// this seems like it would not get all cases...
RegistryKey keyPdfApp = key.OpenSubKey( classNames[0], false);
ReaderPath = GetCommand(keyP dfApp);
}
catch
{
MessageBox.Show (this, "Error: could not find Adobe Acrobat Reader",
"Launch Error");
}

try
{
// break out the command string from the ReaderPath string
string [] path = ReaderPath.Spli t(new char[] {'\"'});

// launch the reader with the .pdf file in the command line
System.Diagnost ics.Process.Sta rt(path[1], fName);
}
catch ( Exception ex )
{
MessageBox.Show (ex.Message);
}
}
// returns the command string or String.Empty
private string GetCommand(Regi stryKey key)
{
string [] names = key.GetSubKeyNa mes();

if ( names == null )
return String.Empty;

foreach ( string name in names )
{
RegistryKey subkey = key.OpenSubKey( name, false);

string [] substrings = (subkey.Name).S plit(new char [] {'\\'});

// see if this is the key ending in "command"
if ( substrings[substrings.Leng th-1] == "command" )
{
// return the default value
return ((string)subkey .GetValue(""));
}

// not found - recurse the subkey
string command = GetCommand(subk ey);
if ( command != String.Empty )
return command;
}

return String.Empty;
}

Thanks for any help.

Alfredo

[Jim Hughes]

Sounds like the long way to get there ... :)

How about using:

System.Diagnost ics.Process.Sta rt(tbFile.Text. Trim());

This will open the application or the application associated with the file
and open the file.

"David Rose" <Da********@rcn .com> wrote in message
news:eS******** ******@tk2msftn gp13.phx.gbl...

Hi,

I am trying to launch pdf files (in this case). The test application takes the path to the pdf from a TextBox when the user clicks a button. I have
written code that works on my computer, but I have doubts that my method is universal.

Basically, in HKEY_CLASSES_RO OT, I look up the .pdf extension and get the
human readable class id. Then I look that up, recursing through the tree
until I get to "command" and then return that value. This seems to work for the Adobe Acrobat Reader...

There must be some general method that Windows uses to find the application when the user double clicks on a file. Or, is there something in the .NET
Framework to accomplish this?

Here is my code:

private void OnViewFileClick (object sender, System.EventArg s e)
{
string fName = tbFile.Text.Tri m();

if ( !File.Exists(fN ame) )
{
MessageBox.Show (this, "File " + fName + " does not exist", "File IO
Error");
return;
}

string ReaderPath = String.Empty;
try
{
RegistryKey key = Registry.Classe sRoot;
RegistryKey keyPDF = key.OpenSubKey( ".pdf", false);
string [] classNames = keyPDF.GetSubKe yNames();

if ( classNames == null )
{
MessageBox.Show (this, "No application associated with the .pdf
extension");
return;
}

// this seems like it would not get all cases...
RegistryKey keyPdfApp = key.OpenSubKey( classNames[0], false);
ReaderPath = GetCommand(keyP dfApp);
}
catch
{
MessageBox.Show (this, "Error: could not find Adobe Acrobat Reader",
"Launch Error");
}

try
{
// break out the command string from the ReaderPath string
string [] path = ReaderPath.Spli t(new char[] {'\"'});

// launch the reader with the .pdf file in the command line
System.Diagnost ics.Process.Sta rt(path[1], fName);
}
catch ( Exception ex )
{
MessageBox.Show (ex.Message);
}
}
// returns the command string or String.Empty
private string GetCommand(Regi stryKey key)
{
string [] names = key.GetSubKeyNa mes();

if ( names == null )
return String.Empty;

foreach ( string name in names )
{
RegistryKey subkey = key.OpenSubKey( name, false);

string [] substrings = (subkey.Name).S plit(new char [] {'\\'});

// see if this is the key ending in "command"
if ( substrings[substrings.Leng th-1] == "command" )
{
// return the default value
return ((string)subkey .GetValue(""));
}

// not found - recurse the subkey
string command = GetCommand(subk ey);
if ( command != String.Empty )
return command;
}

return String.Empty;
}

Thanks for any help.

Alfredo

[David Rose]

Well...

I, um, thought that you had to... well, you know... I mean... Works like
that does it?

Boy, do I feel silly.

Thanks.

"Jim Hughes" <NO*********@Ho tmail.com> wrote in message
news:#W******** ******@tk2msftn gp13.phx.gbl...

Sounds like the long way to get there ... :)

How about using:

System.Diagnost ics.Process.Sta rt(tbFile.Text. Trim());

This will open the application or the application associated with the file
and open the file.

"David Rose" <Da********@rcn .com> wrote in message
news:eS******** ******@tk2msftn gp13.phx.gbl...

Hi,

I am trying to launch pdf files (in this case). The test application

takes

the path to the pdf from a TextBox when the user clicks a button. I have written code that works on my computer, but I have doubts that my method

is

universal.

Basically, in HKEY_CLASSES_RO OT, I look up the .pdf extension and get the human readable class id. Then I look that up, recursing through the tree until I get to "command" and then return that value. This seems to work

for

the Adobe Acrobat Reader...

There must be some general method that Windows uses to find the

application

when the user double clicks on a file. Or, is there something in the ..NET Framework to accomplish this?

Here is my code:

private void OnViewFileClick (object sender, System.EventArg s e)
{
string fName = tbFile.Text.Tri m();

if ( !File.Exists(fN ame) )
{
MessageBox.Show (this, "File " + fName + " does not exist", "File IO
Error");
return;
}

string ReaderPath = String.Empty;
try
{
RegistryKey key = Registry.Classe sRoot;
RegistryKey keyPDF = key.OpenSubKey( ".pdf", false);
string [] classNames = keyPDF.GetSubKe yNames();

if ( classNames == null )
{
MessageBox.Show (this, "No application associated with the .pdf
extension");
return;
}

// this seems like it would not get all cases...
RegistryKey keyPdfApp = key.OpenSubKey( classNames[0], false);
ReaderPath = GetCommand(keyP dfApp);
}
catch
{
MessageBox.Show (this, "Error: could not find Adobe Acrobat Reader",
"Launch Error");
}

try
{
// break out the command string from the ReaderPath string
string [] path = ReaderPath.Spli t(new char[] {'\"'});

// launch the reader with the .pdf file in the command line
System.Diagnost ics.Process.Sta rt(path[1], fName);
}
catch ( Exception ex )
{
MessageBox.Show (ex.Message);
}
}
// returns the command string or String.Empty
private string GetCommand(Regi stryKey key)
{
string [] names = key.GetSubKeyNa mes();

if ( names == null )
return String.Empty;

foreach ( string name in names )
{
RegistryKey subkey = key.OpenSubKey( name, false);

string [] substrings = (subkey.Name).S plit(new char [] {'\\'});

// see if this is the key ending in "command"
if ( substrings[substrings.Leng th-1] == "command" )
{
// return the default value
return ((string)subkey .GetValue(""));
}

// not found - recurse the subkey
string command = GetCommand(subk ey);
if ( command != String.Empty )
return command;
}

return String.Empty;
}

Thanks for any help.

Alfredo

[Jim Hughes]

Maybe so... But I won't tell anyone! :)

But look at how much you learned!

"David Rose" <Da********@rcn .com> wrote in message
news:OC******** ******@tk2msftn gp13.phx.gbl...

Well...

I, um, thought that you had to... well, you know... I mean... Works like that does it?

Boy, do I feel silly.

Thanks.

"Jim Hughes" <NO*********@Ho tmail.com> wrote in message
news:#W******** ******@tk2msftn gp13.phx.gbl...

Sounds like the long way to get there ... :)

How about using:

System.Diagnost ics.Process.Sta rt(tbFile.Text. Trim());

This will open the application or the application associated with the file and open the file.

<snip>

[Mark Rae]

"Jim Hughes" <NO*********@Ho tmail.com> wrote in message
news:u6******** ******@TK2MSFTN GP11.phx.gbl...

Maybe so... But I won't tell anyone! :)

But look at how much you learned!

Ah yes, but if you can tell me how to *print* a PDF using a similar
technique, then I'll really be impressed... :-)

By which, I mean without leaving the Adobe reader open on the taskbar...

[cody]

> Ah yes, but if you can tell me how to *print* a PDF using a similar

technique, then I'll really be impressed... :-)

By which, I mean without leaving the Adobe reader open on the taskbar...

Maybe you have to add a parameter like /print or similar to the argument
string.

--
cody

Freeware Tools, Games and Humour
http://www.deutronium.de.vu || http://www.deutronium.tk

[Mark Rae]

"cody" <no************ ****@gmx.net> wrote in message
news:OR******** *****@TK2MSFTNG P10.phx.gbl...

Ah yes, but if you can tell me how to *print* a PDF using a similar
technique, then I'll really be impressed... :-)

By which, I mean without leaving the Adobe reader open on the taskbar...

Maybe you have to add a parameter like /print or similar to the argument
string.

Nope...

[Jason]

Mark,
See if this will work for you.

System.Diagnost ics.ProcessStar tInfo psi = new
System.Diagnost ics.ProcessStar tInfo();
psi.UseShellExe cute = true;
psi.Verb = "print";
psi.WindowStyle = System.Diagnost ics.ProcessWind owStyle.Normal;
psi.Arguments = "/p";
psi.FileName = @"C:\SomePDF.pd f";
System.Diagnost ics.Process p = System.Diagnost ics.Process.Sta rt(psi);
p.WaitForInputI dle();
p.CloseMainWind ow();

Jason Newell (MCAD)
Software Engineer
The Charles Machine Works, Inc.

"Mark Rae" <ma**@markrae.c o.uk> wrote in message
news:ec******** ******@TK2MSFTN GP11.phx.gbl...

"Jim Hughes" <NO*********@Ho tmail.com> wrote in message
news:u6******** ******@TK2MSFTN GP11.phx.gbl...

Maybe so... But I won't tell anyone! :)

But look at how much you learned!

Ah yes, but if you can tell me how to *print* a PDF using a similar
technique, then I'll really be impressed... :-)

By which, I mean without leaving the Adobe reader open on the taskbar...

[Mark Rae]

"Jason" <no****@nospam. com> wrote in message
news:%2******** ********@TK2MSF TNGP12.phx.gbl. ..

Jason,

See if this will work for you.
I've tried many different variants of similar code. It works, of course,
inasmuch as it prints the PDF document, but the main problem is that it
leaves the Adobe Reader window minimised on the taskbar in run mode though,
curiously, not in debug mode... In debug mode, the code halts for upwards of
30 seconds on the line
p.WaitForInputI dle();

but in run mode it seems to determine that the process is idle pretty much
immediately. It then tries to close the window but can't because it's still
busy.

Thanks for the reply.

Mark

[Jason]

Mark,
Here's a long shot for you. Have you ever seen
http://www.ghostscript.com/. I actually have a C# project that runs
ghostscript in batch mode using P/Invoke. Ghostcript has a ton of options,
as far as printing any file, or converting any file format to almost any
file format. It works very well for me. Not sure about your situation.
What I ended up using it for, was to convert the .pdf to an image and
dealing with the image from that point. ghostscript is a very powerful too.
Very difficult to get started with, but once you get the hang of it, it's
really cool. If this sounds like something you'd be interested in, I'd be
happy to share my C# ghostscript wrapper class with you. Talk to you later.

Jason Newell (MCAD)
Software Engineer
The Charles Machine Works, Inc.

"Mark Rae" <ma**@markrae.c o.uk> wrote in message
news:u$******** ******@TK2MSFTN GP10.phx.gbl...

"Jason" <no****@nospam. com> wrote in message
news:%2******** ********@TK2MSF TNGP12.phx.gbl. ..

Jason,

See if this will work for you.
I've tried many different variants of similar code. It works, of course,
inasmuch as it prints the PDF document, but the main problem is that it
leaves the Adobe Reader window minimised on the taskbar in run mode

though, curiously, not in debug mode... In debug mode, the code halts for upwards of 30 seconds on the line

p.WaitForInputI dle();
but in run mode it seems to determine that the process is idle pretty much
immediately. It then tries to close the window but can't because it's

still busy.

Thanks for the reply.

Mark