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Re^4: PDF Document Level Script

by Arik123 (Sexton)
on Jan 11, 2018 at 11:06 UTC ( #1207113=note: print w/replies, xml ) Need Help??


in reply to Re^3: PDF Document Level Script
in thread PDF Document Level Script

Okay, there is a way to modify document-level JS with CAM::PDF. I created a PDF with document-level JS, and below is how I replace it with a new JS code. Note that your template may work differently. For example, the JS code is stored in a pdf object, which may contain its length, or alternatively contain a reference to another pdf object that contains the length.

my $pdf = CAM::PDF->new($file); my $p3 = $pdf->getObjValue($pdf->getObjValue($pdf->getObjValue($pdf->g +etRootDict()->{Names}{value}{JavaScript}{value})->{Names}{value}[1]{v +alue})->{JS}{value}); $p3->{StreamData}{value} = <<EO_JS; this.getField("AfterSave1").display = display.hidden; this.getField("AfterSave2").display = display.hidden; this.dirty=false; EO_JS $n = $pdf->dereference(CAM::PDF::Node->new('reference', $p3->{Length}{ +value})->{value}); $n->{value}{value} = length $p3->{StreamData}{value};;

For some reason, I'm not sure that's the way CAM::PDF was meant to be used...

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Re^5: PDF Document Level Script
by vr (Curate) on Jan 11, 2018 at 17:42 UTC
    For some reason, I'm not sure that's the way CAM::PDF was meant to be used...

    :-) Maybe not. Here I formatted your code a little, to be able to read it:

    my $pdf = CAM::PDF-> new( $file ); my $p3 = $pdf-> getObjValue( $pdf-> getObjValue( $pdf-> getObjValue( $pdf-> getRootDict-> { Names }{ value }{ JavaScript }{ val +ue } )->{ Names }{ value }[ 1 ]{ value } )-> { JS }{ value } ); $p3-> { StreamData }{ value } = << EO_JS; this.getField("AfterSave1").display = display.hidden; this.getField("AfterSave2").display = display.hidden; this.dirty=false; EO_JS $n = $pdf-> dereference( CAM::PDF::Node-> new( 'reference', $p3-> { Length }{ value })-> { +value } ); $n->{ value }{ value } = length $p3-> { StreamData }{ value };

    It's good you found solution that works for your template, and I understand (you said it yourself) this code wasn't meant to be universal. And yet, it wasn't necessary to make so many assumptions.

    $pdf-> getObjValue( $node-> { value }) $pdf-> getObjValue( $node-> { value }{ a_key }{ value })

    In 1st line, node's type is assumed to be 'reference' (i.e., it's indirect object in PDF structure). In 2nd line it's assumed to be direct object, in this case node's type is 'dictionary', which dictionary has an entry keyed by 'a_key' which (entry), in turn, is assumed to be indirect object, i.e. that node's type assumed as 'reference'! Don't do that. Consider:

    $pdf-> getObjValue( $node-> { value }) $pdf-> getValue( $node )

    If node's type is 'reference', then these 2 lines return same result. But, not only 2nd line is shorter, it will also work for direct objects, i.e. if node's type is dictionary, array, number, etc. In fact, I don't remember to ever use the getObjValue.

    CAM::PDF::Node-> new( 'reference', $node-> { value })-> { value } $node-> { value }

    These 2 lines produce the same result :-) (i.e., if node's type is 'reference'). But of course it's better to add new stream using designated method, then it won't be necessary to hack the 'Length' property (it will be added automatically).

    use strict; use warnings; use feature 'say'; use CAM::PDF; sub _n { CAM::PDF::Node-> new( @_ )} my $js_code = << 'EO_JS'; this.getField("AfterSave1").display = display.hidden; this.getField("AfterSave2").display = display.hidden; this.dirty=false; EO_JS my $file = $ARGV[ 0 ] or die; my $pdf = CAM::PDF-> new( $file ) or die; my $root = $pdf-> getRootDict; my $names_dict = $pdf-> getValue( $root-> { Names }); my $js_tree = $pdf-> getValue( $names_dict-> { JavaScript }); my $js_tree_root_ary = $pdf-> getValue( $js_tree-> { Names }); my $js_code_stream = $pdf-> createStreamObject( $js_code, 'FlateDeco +de' ); my $js_code_obj = $pdf-> appendObject( undef, $js_code_stream, 0 +); my $js_code_ref = _n( reference => $js_code_obj ); my $js_action_dict = _n( dictionary => { JS => $js_code_ref, S => _n( label => 'JavaScript' ), }); my $js_action_obj = $pdf-> appendObject( undef, _n( object => $js_a +ction_dict ), 0 ); my $js_action_ref = _n( reference => $js_action_obj ); my $js_code_name = _n( label => 'my_js_code' ); push @{ $js_tree_root_ary }, $js_code_name, $js_action_ref; $file =~ s/\.pdf$/++$&/i; $pdf-> cleanoutput( $file );

    The only assumption (i.e. no checks) in code above is that input file already has some 'document-level javascript'. Then we just push 2 new entries into already existing array. However, I suspect that it is some dummy JS in your template, since you replace it (not append) with new code. Then, it wasn't necessary to stuff this dummy JS into template to begin with, you could add all necessary top level structures programmatically (similar to what is shown above). Try it for exercise, if so desired :-).

Re^5: PDF Document Level Script
by marto (Cardinal) on Jan 11, 2018 at 11:25 UTC

    Nice! Also thanks for the update, hopefully this will be useful to someone in future. I haven't had cause to work with PDFs for some time now.

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