[Mapserver-users] Sending images with mod_perl (solution #1)
Mark Cave-Ayland
m.cave-ayland@webbased.co.uk
Sun, 25 May 2003 18:42:38 +0100
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Hi everyone,
After a couple of weeks of looking at this problem 'out of hours', I've
eventually come up with a solution that allows perl mapscript to run
under mod_perl and output images directly to the browser without having
to write a temporary file to disk first.
Having looked at the various issues involved, I decided against
redirecting file handles as in Jason's patches, as it seemed some kind
of mystical voodoo occurs when Apache redirects stdout into a socket
with things coming out in the wrong order or not at all. So I decided to
approach it from the angle of getting the image in a variable so that
mod_perl can output it directly.
Looking at mapscript.i, it looked as if someone had already written
something similar; a method called getImageToVar() which worked under
Tcl to set a new variable with the contents of the rendered image. So I
set about adding in equivalent perl methods to achieve the same effect.
However, setting named variables in perl appeared to create them in a
global scope (which is not good for mod_perl) which is why my solution
returns a new scalar from the method.
Please find attached the patch against mapserver 3.6.5 for
comment/testing. I'm afraid the patch removes the existing Tcl function
because I've never used Tcl before so testing it would be hard; however
to add it back in should just be a case of adding a few lines to create
a new typemap.
Once the attached patch has been applied, the mapscript_wrap.c and
mapscript.pm modules need to be recreated with SWiG; I used SWiG 1.3.19
which gave a lot of warnings but the resulting wrappers worked fine. The
modified getImageToVar() method can then be used like this:
#!/usr/bin/perl
# Output the content-type header
use CGI ':cgi';
print header( # note the use of the filehandle here...
-type => 'image/png',
);
# The actual mapscript itself goes here
$ENV{MS_ERRORFILE} = "/var/www/perl/mserr.log";
use mapscript;
# Create a new map
my $map = new mapscript::mapObj('/var/www/perl/mstest.map');
# Draw the map
my $mapimg = $map->draw();
# Get the resulting image as a scalar
my $rawimg;
$rawimg = $map->getImageToVar($mapimg);
# Send it to the browser
print $rawimg;
While this may not be the solution originally envisaged, it appears to
be working well here on a development system. Feel free to stress it,
test it, benchmark it and find any memory leaks - but remember this code
is experimental ;)
Cheers,
Mark.
---
Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England
Tel: +44 (0)1752 764445
Fax: +44 (0)1752 764446
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filename="mapserver-3.6.5-getimage.patch"
--- mapserver-3.6.5.vanilla/map.h Tue Mar 18 16:04:26 2003=0A=
+++ mapserver-3.6.5/map.h Sun May 25 12:48:17 2003=0A=
@@ -726,6 +726,11 @@=0A=
webObj web;=0A=
=0A=
int *layerorder;=0A=
+=0A=
+#ifndef SWIG=0A=
+ char *imagedata; /* output image rendered by gd library */=0A=
+ int imagelen;=0A=
+#endif=0A=
=0A=
} mapObj;=0A=
=0A=
--- mapserver-3.6.5.vanilla/mapfile.c Sat Feb 8 17:16:23 2003=0A=
+++ mapserver-3.6.5/mapfile.c Sun May 25 12:49:36 2003=0A=
@@ -3000,6 +3004,8 @@=0A=
=0A=
map->transparent =3D MS_OFF;=0A=
map->interlace =3D MS_ON;=0A=
+ map->imagedata =3D NULL;=0A=
+ map->imagelen =3D 0;=0A=
=0A=
map->labelcache.labels =3D (labelCacheMemberObj =
*)malloc(sizeof(labelCacheMemberObj)*MS_LABELCACHEINITSIZE);=0A=
if(map->labelcache.labels =3D=3D NULL) {=0A=
@@ -3094,6 +3100,9 @@=0A=
if (map->layerorder)=0A=
free(map->layerorder);=0A=
=0A=
+ if (map->imagedata)=0A=
+ free(map->imagedata);=0A=
+=0A=
msFree(map);=0A=
}=0A=
=0A=
--- mapserver-3.6.5.vanilla/mapscript/mapscript.i Mon Jul 8 18:28:16 =
2002=0A=
+++ mapserver-3.6.5/mapscript/mapscript.i Sun May 25 12:51:47 2003=0A=
@@ -237,92 +237,95 @@=0A=
return msDrawLabelCache(image->bytes, self);=0A=
}=0A=
=0A=
- int getImageToVar(imageObj *image, char *varname) {=0A=
- // set a scripting language variable by name with image data=0A=
- int size =3D 0;=0A=
- unsigned char *imgbytes;=0A=
-=0A=
- // Tcl implementation to define needed variables, initialization=0A=
- #ifdef SWIGTCL8=0A=
- Tcl_Obj *imgobj;=0A=
- int flags =3D TCL_LEAVE_ERR_MSG;=0A=
- /* no other initialization needed */=0A=
- #endif=0A=
-=0A=
- // Perl implementation to define needed variables, initialization=0A=
- #ifdef SWIGPERL=0A=
- #endif=0A=
-=0A=
- // Python implementation to define needed variables, initialization=0A=
- #ifdef SWIGPYTHON=0A=
- #endif=0A=
-=0A=
- // generic code to get imgbytes, size=0A=
- switch (self->imagetype) {=0A=
- case(MS_GIF):=0A=
- #ifdef USE_GD_GIF=0A=
- // GD /w gif doesn't have gdImageGifPtr()=0A=
- msSetError(MS_MISCERR, "GIF output is not available.",=0A=
- "getImageToVar()");=0A=
- return(MS_FAILURE);=0A=
- #endif=0A=
- break;=0A=
- case(MS_PNG):=0A=
- #ifdef USE_GD_PNG=0A=
- imgbytes =3D gdImagePngPtr(image->bytes, &size);=0A=
- #else=0A=
- msSetError(MS_MISCERR, "PNG output is not available.",=0A=
- "getImageToVar()");=0A=
- return(MS_FAILURE);=0A=
- #endif=0A=
- break;=0A=
- case(MS_JPEG):=0A=
- #ifdef USE_GD_JPEG=0A=
- imgbytes =3D gdImageJpegPtr(image->bytes, &size, =
self->imagequality);=0A=
- #else=0A=
- msSetError(MS_MISCERR, "JPEG output is not available.",=0A=
- "getImageToVar()");=0A=
- return(MS_FAILURE);=0A=
- #endif=0A=
- break;=0A=
- case(MS_WBMP):=0A=
- #ifdef USE_GD_WBMP=0A=
- imgbytes =3D gdImageWBMPPtr(image->bytes, &size, 1);=0A=
- #else=0A=
- msSetError(MS_MISCERR, "WBMP output is not available.",=0A=
- "getImageToVar()");=0A=
- return(MS_FAILURE);=0A=
- #endif=0A=
- break;=0A=
- default:=0A=
- msSetError(MS_MISCERR, "Unknown output image type.",=0A=
- "getImageToVar()");=0A=
- return(MS_FAILURE);=0A=
- }=0A=
-=0A=
-=0A=
- // Tcl implementation to set variable=0A=
- #ifdef SWIGTCL8=0A=
- imgobj =3D Tcl_NewByteArrayObj(imgbytes, size);=0A=
- Tcl_IncrRefCount(imgobj);=0A=
- Tcl_SetVar2Ex(SWIG_TCL_INTERP, varname, (char *)NULL, imgobj, =
flags);=0A=
- Tcl_DecrRefCount(imgobj);=0A=
- gdFree(imgbytes);=0A=
- return MS_SUCCESS;=0A=
- #endif=0A=
-=0A=
- // Perl implementation to set variable=0A=
- #ifdef SWIGPERL=0A=
- #endif=0A=
-=0A=
- // Python implementation to set variable=0A=
- #ifdef SWIGPYTHON=0A=
- #endif=0A=
-=0A=
- // return failure for unsupported swig languages=0A=
- msSetError(MS_MISCERR, "Unsupported scripting language.",=0A=
- "getImageToVar()");=0A=
- return MS_FAILURE;=0A=
+=0A=
+/* Typemaps to allow function to return binary data */=0A=
+#ifdef SWIGPERL=0A=
+%typemap(in,numinputs=3D0) char *OUTPUT=0A=
+ {=0A=
+ }=0A=
+ =0A=
+ %typemap(argout) char *OUTPUT=0A=
+ {=0A=
+ SV *newscalar;=0A=
+ =0A=
+ newscalar =3D sv_newmortal();=0A=
+ sv_setpvn(newscalar, arg1->imagedata, arg1->imagelen);=0A=
+ ST(argvi++) =3D newscalar;=0A=
+ }=0A=
+#endif=0A=
+=0A=
+=0A=
+ void getImageToVar(imageObj *image, char *OUTPUT) {=0A=
+ =0A=
+ // return the rendered image data back to the script=0A=
+ void *imgtmp;=0A=
+ int imglen;=0A=
+=0A=
+ // Check interlace and transparency parameters=0A=
+ if(self->interlace)=0A=
+ gdImageInterlace(image->bytes, 1);=0A=
+=0A=
+ if(self->transparent)=0A=
+ gdImageColorTransparent(image->bytes, 0);=0A=
+=0A=
+ // Free any existing rendered image data=0A=
+ if (self->imagedata !=3D NULL) free(self->imagedata);=0A=
+=0A=
+=0A=
+ // generic code to get imgbytes, size=0A=
+ switch (self->imagetype) {=0A=
+ case(MS_GIF):=0A=
+ %#ifdef USE_GD_GIF=0A=
+ // GD /w gif doesn't have gdImageGifPtr()=0A=
+ msSetError(MS_MISCERR, "GIF output is not available.", =
"getImageToVar()");=0A=
+ return;=0A=
+ %#endif=0A=
+ break;=0A=
+=0A=
+ case(MS_PNG):=0A=
+ %#ifdef USE_GD_PNG=0A=
+ imgtmp =3D gdImagePngPtr(image->bytes, &imglen);=0A=
+ self->imagedata =3D malloc(imglen);=0A=
+ memcpy(self->imagedata, imgtmp, imglen);=0A=
+ self->imagelen =3D imglen;=0A=
+ gdFree(imgtmp);=0A=
+ return;=0A=
+ %#else=0A=
+ msSetError(MS_MISCERR, "PNG output is not available.", =
"getImageToVar()");=0A=
+ %#endif=0A=
+ break;=0A=
+=0A=
+ case(MS_JPEG):=0A=
+ %#ifdef USE_GD_JPEG=0A=
+ imgtmp =3D gdImageJpegPtr(image->bytes, &imglen, self->imagequality);=0A=
+ self->imagedata =3D malloc(imglen);=0A=
+ memcpy(self->imagedata, imgtmp, imglen);=0A=
+ self->imagelen =3D imglen;=0A=
+ gdFree(imgtmp);=0A=
+ %#else=0A=
+ msSetError(MS_MISCERR, "JPEG output is not available.", =
"getImageToVar()");=0A=
+ return;=0A=
+ %#endif=0A=
+ break;=0A=
+=0A=
+ case(MS_WBMP):=0A=
+ %#ifdef USE_GD_WBMP=0A=
+ imgtmp =3D gdImageWBMPPtr(image->bytes, &imglen, 1);=0A=
+ self->imagedata =3D malloc(imglen);=0A=
+ memcpy(self->imagedata, imgtmp, imglen);=0A=
+ self->imagelen =3D imglen;=0A=
+ gdFree(imgtmp);=0A=
+ %#else=0A=
+ msSetError(MS_MISCERR, "WBMP output is not available.", =
"getImageToVar()");=0A=
+ return;=0A=
+ %#endif=0A=
+ break;=0A=
+=0A=
+ }=0A=
+=0A=
+ // return failure for unsupported swig languages=0A=
+ msSetError(MS_MISCERR, "Unsupported scripting language.", =
"getImageToVar()");=0A=
+ return;=0A=
}=0A=
=0A=
labelCacheMemberObj *nextLabel() {=0A=
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