func refToken(f fancy.Reader) ([]byte, int64) {
tok, p := ps.Token(f)
if len(tok) > 0 && tok[0] >= '0' && tok[0] <= '9' {
ps.Token(f)
r, q := ps.Token(f)
if string(r) == "R" {
f.Seek(p, 0)
tok = f.Slice(int(1 + q - p))
} else {
f.Seek(p+int64(len(tok)), 0)
}
}
return tok, p
}
func tupel(f fancy.Reader, count int) [][]byte {
r := make([][]byte, count)
for i := 0; i < count; i++ {
r[i], _ = ps.Token(f)
}
return r
}
// xrefSkip() queries the start of the trailer for a (partial) xref-table.
func xrefSkip(f fancy.Reader, xref int) int {
f.Seek(int64(xref), 0)
t, p := ps.Token(f)
if string(t) != "xref" {
return -1
}
for {
t, p = ps.Token(f)
if t[0] < '0' || t[0] > '9' {
f.Seek(p, 0)
break
}
t, _ = ps.Token(f)
ps.SkipLE(f)
f.Seek(int64(num(t)*20), 1)
}
r, _ := f.Seek(0, 1)
return int(r)
}
// xrefRead() reads the xref table(s) of a PDF file. This is not recursive
// in favour of not to have to keep track of already used starting points
// for xrefs.
func xrefRead(f fancy.Reader, p int) map[int]int {
var back [MAX_PDF_UPDATES]int
b := 0
s := _Bytes
for ok := true; ok; {
back[b] = p
b++
p = xrefSkip(f, p)
f.Seek(int64(p), 0)
s, _ = ps.Token(f)
if string(s) != "trailer" {
return nil
}
s, _ = ps.Token(f)
s, ok = Dictionary(s)["/Prev"]
p = num(s)
}
r := make(map[int]int)
for b != 0 {
b--
f.Seek(int64(back[b]), 0)
ps.Token(f) // skip "xref"
for {
m := tupel(f, 2)
if string(m[0]) == "trailer" {
break
}
ps.SkipLE(f)
o := num(m[0])
dat := f.Slice(num(m[1]) * 20)
for i := 0; i < len(dat); i += 20 {
if dat[i+17] != 'n' {
r[o] = 0, false
} else {
r[o] = num(dat[i : i+10])
}
o++
}
}
}
return r
}
// pd.Stream() returns contents of a stream.
func (pd *PdfReaderT) Stream(reference []byte) (DictionaryT, []byte) {
q, d := pd.Resolve(reference)
dic := pd.Dic(d)
l := pd.Num(dic["/Length"])
pd.rdr.Seek(int64(q), 0)
t, _ := ps.Token(pd.rdr)
if string(t) != "stream" {
return nil, []byte{}
}
ps.SkipLE(pd.rdr)
return dic, pd.rdr.Slice(l)
}
// Load() loads a PDF file of a given name.
func Load(fn string) *PdfReaderT {
r := new(PdfReaderT)
r.File = fn
r.rdr = fancy.FileReader(fn)
if r.Startxref = xrefStart(r.rdr); r.Startxref == -1 {
return nil
}
if r.Xref = xrefRead(r.rdr, r.Startxref); r.Xref == nil {
return nil
}
r.rdr.Seek(int64(xrefSkip(r.rdr, r.Startxref)), 0)
s, _ := ps.Token(r.rdr)
if string(s) != "trailer" {
return nil
}
s, _ = ps.Token(r.rdr)
if r.Trailer = Dictionary(s); r.Trailer == nil {
return nil
}
r.rcache = make(map[string][]byte)
r.rncache = make(map[string]int)
r.dicache = make(map[string]DictionaryT)
return r
}
// Dictionary() makes a map/hash from PDF dictionary data.
func Dictionary(s []byte) DictionaryT {
if len(s) < 4 {
return nil
}
e := len(s) - 1
if s[0] != s[1] || s[0] != '<' || s[e] != s[e-1] || s[e] != '>' {
return nil
}
r := make(DictionaryT)
rdr := fancy.SliceReader(s[2 : e-1])
for {
t, _ := ps.Token(rdr)
if len(t) == 0 {
break
}
if t[0] != '/' {
return nil
}
k := string(t)
t, _ = refToken(rdr)
r[k] = t
}
return r
}
