[Mapserver-users] Sending image to stdout under Apache

[Lowell Filak]

Doh!
That's what I get for being in a hurry.
>From what I've read:
1) You don't need binmode on *n*x.
2) You need to print to OUT as opposed to STDOUT or the content is shipped before the content-type.
print OUT $ref_img->saveImage(undef, $mapscript::MS_PNG, $map->{transparent}, $map->{interlace}, 0);
HTH
Lowell F.

The following message was sent by Eric Bridger <eric at gomoos.org> on 05 Mar 2003 10:57:23 +0000.

> Thanks Lowell,
> 
> Yes, that was the work-around I mentioned.  But avoiding the write to
> disk is what I am after.  I have found that using /cgi-bin/mapserv as an
> image engine results in significant performance improvements for our
> mapscript application.  But constructing the proper query strings to
> manipulate the map is cumbersome and seems to have certain limitations. 
> I'd prefer to manipulate the map using mapscript and then print it to
> the stdout. But somehow, using $img->saveImage(undef, ...) which spends
> some time doing something, never sends the image to the stdout when run
> as a CGI.  From the command line, it works.
> 
> We don't have this problem with a graphing application in the same
> environment which uses GD.pm.
> 
> 
> On Wed, 2003-03-05 at 15:27, Lowell Filak wrote:
> > Hmmm...
> > I thought I replied back concerning that.?
> > Just do a:
> > print "Content-type: image/png\n\n";
> > system("cat junk.png");
> > and that will send the image to stdout/the browser.
> > HTH
> > Lowell F.
> > 
> > The following message was sent by Eric Bridger <eric at gomoos.org> on 05 Mar 2003 08:59:12 +0000.
> > 
> > > 
> > > 
> > > The list archives show that this came up last Dec.
> > > (http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0212/msg00265.html) and while a work around was suggested there was no solution to the problem given, so I was wondering if anyone else had run into this problem. 
> > > 
> > > I'm having a problem using Perl mapscript $img->saveImage(undef, ...),
> > > to send an image, PNG and/or JPEG, to the standard output under Apache. 
> > > Running in /cgi-bin I have the following script: 
> > > 
> > > my $map = new mapscript::mapObj($ms_dir . "/test.map"); 
> > > 
> > > my $ref_img = $map->drawReferenceMap(); 
> > > 
> > > # This works fine: 
> > > #$ref_img->saveImage("junk.png", $mapscript::MS_PNG,  
> > > $map->{transparent}, $map->{interlace}, 0); 
> > > 
> > > print "HTTP/1.0 200 OK\n"; 
> > > print "Content-type: image/png\r\n\r\n"; 
> > > binmode STDOUT; 
> > > 
> > > # this produces no output on Apache's STDOUT 
> > > $ref_img->saveImage("", $mapscript::MS_PNG, $map->{transparent},
> > > $map->{interlace}, 0); 
> > > 
> > > $ref_img->free(); 
> > > exit; 
> > > 
> > > 
> > > >From the command line this script works as expected.  But when run under
> > > Apache/mod_perl  it's as if the C msSaveImage() stdout stream is
> > > pointing somewhere other than the Apache stdout (i.e. the client
> > > browser). 
> > > 
> > > The work around of course is to save a disk file and then print it, but
> > > the whole point of this is to avoid the temp. disk files.  I've noticed
> > > a significant increase in performance when using mapserv as an image
> > > engine rather then using temp disk files. 
> > > 
> > > Thanks. 
> > > Eric 
> > > 
> > > 
> > > Setup: 
> > > 
> > > Apache/1.3.26 (Unix) 
> > > Mapserv 3.6.4 
> > > mod_perl 1.22 
> > > 
> > > 
> > > _______________________________________________
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> > > Mapserver-users at lists.gis.umn.edu
> > > http://lists.gis.umn.edu/mailman/listinfo/mapserver-users
> > 
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> > 
> 
> 
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