1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
#ifndef PDF_PDF_H
#define PDF_PDF_H
#include <string>
#include "Iref.h"
#include "../Page_no/PS_page_numbering.h"
// ---------------------------------------------------------------------
// To interpret a PDF, through an interface narrower
// and more conventional than LibPoppler's.
// ---------------------------------------------------------------------
// Caution: One should view code which calls PDF::PDF::get_PDFDoc_ptr()
// with suspicion. The function is a hack necessary for some purposes
// which, when used, unfortunately violates encapsulation.
// Some notes on this module:
//
// 1. Various of the comments in this file, in the corresponding *.cc
// and maybe elsewhere would seem to suggest that Libpoppler were
// somehow deficient. On the contrary, this programmer appreciates the
// availability of Libpoppler and is very glad that it frees him from
// the need independently to implement its relevant functionality! Of
// course Libpoppler could be improved significantly with commensurate
// programming effort (by someone), as could most code including the
// code you are now reading, but this is not the point. The only point
// is that the present code is written in view of the admittedly archaic
// interface Libpoppler happens to provide. The purpose of the comments
// is not to critize Libpoppler (as if anyone seeking criticism of
// Libpoppler would look for it here) but rather solely to explain why
// the present code, which uses Libpoppler, does certain things in a way
// less than obvious to a typical modern C++ programmer.
//
// 2. In many established modules, one tends to avoid adding new
// symbols unnecessarily, but users of this module should expect new
// symbols to be added at any time. This is because the module's
// purpose is less to provide its users a thin, stable interface than to
// remove one step from them Libpoppler's interface.
//
//
namespace PDF {
struct PDF_rep;
class PDF;
int file_length ( const PDF &pdf );
int offset_last_xref_table( const std::string &pdf_filename );
Iref iref_catalog ( const PDF &pdf );
Iref iref_info ( const PDF &pdf );
int n_obj ( const PDF &pdf );
int offset ( const PDF &pdf, int i );
int n_page ( const PDF &pdf );
int i_page(
const PDF &pdf,
Iref iref,
bool do_not_throw = false
);
Iref iref_page ( const PDF &pdf, int i );
}
class PDF::PDF {
private:
PDF_rep *rep;
public:
// The exception classes are imprecise. Basically, Exc_IO() is
// thrown when the problem seems likely to have involved failure to
// read a file, whereas Exc_PDF() is thrown when the PDF file is
// found but seems to be corrupted. Given the way Libpoppler is
// defined, it would take too much programming effort to be more
// precise, but if one does not like the exception categories given
// then one can always default to catching Exc().
struct Exc {};
struct Exc_IO : public Exc {};
struct Exc_PDF : public Exc {};
explicit PDF( const std::string &filename );
~PDF();
friend int file_length ( const PDF &pdf );
friend int offset_last_xref_table( const std::string &pdf_filename );
friend Iref iref_catalog ( const PDF &pdf );
friend Iref iref_info ( const PDF &pdf );
friend int n_obj ( const PDF &pdf );
friend int offset ( const PDF &pdf, int i );
friend int n_page ( const PDF &pdf );
friend int i_page(
const PDF &pdf,
Iref iref,
bool do_not_throw
);
friend Iref iref_page ( const PDF &pdf, int i );
// The get_PDFDoc_ptr() member function is a necessary hack. Its
// intended user is code which calls Libpoppler to manipulate
// Libpoppler's representation of a PDF object to dump the object to
// a string. Libpoppler's peculiar presentation unfortunately
// renders obvious alternatives impractical or unacceptable. To
// discourage casual or accidental use, the function demands a magic
// integer, the correct value of which you can find hardwired into
// the PDF.cc code.
PDF_rep *get_PDF_rep( int magic );
};
#endif
|
