forked from pdfcpu/pdfcpu
/
filter.go
182 lines (133 loc) · 3.86 KB
/
filter.go
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/*
Copyright 2018 The pdfcpu Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package pdfcpu
// See 7.4 for a list of the defined filters.
import (
"bytes"
"encoding/hex"
"io"
"github.com/hhrutter/pdfcpu/pkg/filter"
"github.com/hhrutter/pdfcpu/pkg/log"
)
func parmsForFilter(d Dict) map[string]int {
m := map[string]int{}
if d == nil {
return m
}
for k, v := range d {
i, ok := v.(Integer)
if ok {
m[k] = i.Value()
continue
}
// Encode boolean values: false -> 0, true -> 1
b, ok := v.(Boolean)
if ok {
m[k] = 0
if b.Value() {
m[k] = 1
}
continue
}
}
return m
}
// encodeStream encodes stream dict data by applying its filter pipeline.
func encodeStream(sd *StreamDict) error {
log.Trace.Printf("encodeStream begin")
// No filter specified, nothing to encode.
if sd.FilterPipeline == nil {
log.Trace.Println("encodeStream: returning uncompressed stream.")
sd.Raw = sd.Content
streamLength := int64(len(sd.Raw))
sd.StreamLength = &streamLength
ok := sd.Insert("Length", Integer(streamLength))
if !ok {
sd.Update("Length", Integer(streamLength))
}
return nil
}
var b io.Reader
b = bytes.NewReader(sd.Content)
var c *bytes.Buffer
// Apply each filter in the pipeline to result of preceding filter.
for _, f := range sd.FilterPipeline {
if f.DecodeParms != nil {
log.Trace.Printf("encodeStream: encoding filter:%s\ndecodeParms:%s\n", f.Name, f.DecodeParms)
} else {
log.Trace.Printf("encodeStream: encoding filter:%s\n", f.Name)
}
// make parms map[string]int
parms := parmsForFilter(f.DecodeParms)
fi, err := filter.NewFilter(f.Name, parms)
if err != nil {
return err
}
c, err = fi.Encode(b)
if err != nil {
return err
}
b = c
}
sd.Raw = c.Bytes()
streamLength := int64(len(sd.Raw))
sd.StreamLength = &streamLength
ok := sd.Insert("Length", Integer(streamLength))
if !ok {
sd.Update("Length", Integer(streamLength))
}
log.Trace.Printf("encodeStream end")
return nil
}
// decodeStream decodes streamDict data by applying its filter pipeline.
func decodeStream(sd *StreamDict) error {
log.Trace.Printf("decodeStream begin \n%s\n", sd)
if sd.Content != nil {
// This stream has already been decoded.
return nil
}
// No filter specified, nothing to decode.
if sd.FilterPipeline == nil {
sd.Content = sd.Raw
log.Trace.Printf("decodedStream returning %d(#%02x)bytes: \n%s\n", len(sd.Content), len(sd.Content), hex.Dump(sd.Content))
return nil
}
var b io.Reader
b = bytes.NewReader(sd.Raw)
//fmt.Printf("decodedStream before:\n%s\n", hex.Dump(sd.Raw))
var c *bytes.Buffer
// Apply each filter in the pipeline to result of preceding filter.
for _, f := range sd.FilterPipeline {
if f.DecodeParms != nil {
log.Trace.Printf("decodeStream: decoding filter:%s\ndecodeParms:%s\n", f.Name, f.DecodeParms)
} else {
log.Trace.Printf("decodeStream: decoding filter:%s\n", f.Name)
}
// make parms map[string]int
parms := parmsForFilter(f.DecodeParms)
fi, err := filter.NewFilter(f.Name, parms)
if err != nil {
return err
}
c, err = fi.Decode(b)
if err != nil {
return err
}
//fmt.Printf("decodedStream after:%s\n%s\n", f.Name, hex.Dump(c.Bytes()))
b = c
}
sd.Content = c.Bytes()
log.Trace.Printf("decodedStream returning %d(#%02x)bytes: \n%s\n", len(sd.Content), len(sd.Content), hex.Dump(c.Bytes()))
//log.Trace.Printf("decodeStream end")
return nil
}