/
legacyconvert.go
77 lines (68 loc) · 2.02 KB
/
legacyconvert.go
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// Copyright 2016 Michael Stapelberg and contributors
//
// 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 legacyconvert contains the not-yet-refactored scan2drive conversion
// logic.
package legacyconvert
import (
"bytes"
"image"
"image/png"
"github.com/stapelberg/scan2drive/internal/g3"
"github.com/stapelberg/scan2drive/internal/page"
"golang.org/x/net/trace"
)
func ConvertLogic(tr trace.Trace, pages []*page.Any) (pdf []byte, thumb []byte, err error) {
compressed := make([]*bytes.Buffer, len(pages))
bounds := make([]image.Rectangle, len(pages))
var first *image.Gray
for idx, page := range pages {
var binarized *image.Gray
{
bin, whitePct, err := page.Binarized()
if err != nil {
return nil, nil, err
}
binarized = bin
blank := whitePct > 0.99
tr.LazyPrintf("white percentage of page %d is %f, blank = %v", idx, whitePct, blank)
if blank {
continue
}
}
if first == nil {
first = binarized
}
// compress
var buf bytes.Buffer
if err := g3.NewEncoder(&buf).Encode(binarized); err != nil {
return nil, nil, err
}
compressed[idx] = &buf
bounds[idx] = binarized.Bounds()
tr.LazyPrintf("g3-compressed into %d bytes", buf.Len())
}
// create thumbnail: PNG-encode the first page
if first != nil {
var buf bytes.Buffer
if err := png.Encode(&buf, first); err != nil {
return nil, nil, err
}
thumb = buf.Bytes()
}
var buf bytes.Buffer
if err := writePDF(&buf, compressed, bounds); err != nil {
return nil, nil, err
}
return buf.Bytes(), thumb, nil
}