Kurt Jungs Auslieferungszustand
This commit is contained in:
213
png.go
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213
png.go
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/*
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* Copyright (c) 2013-2016 Kurt Jung (Gmail: kurt.w.jung)
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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package gofpdf
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import (
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"bytes"
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"fmt"
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"strings"
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)
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func (f *Fpdf) pngColorSpace(ct byte) (colspace string, colorVal int) {
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colorVal = 1
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switch ct {
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case 0, 4:
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colspace = "DeviceGray"
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case 2, 6:
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colspace = "DeviceRGB"
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colorVal = 3
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case 3:
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colspace = "Indexed"
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default:
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f.err = fmt.Errorf("unknown color type in PNG buffer: %d", ct)
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}
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return
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}
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func (f *Fpdf) parsepngstream(buf *bytes.Buffer, readdpi bool) (info *ImageInfoType) {
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info = f.newImageInfo()
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// Check signature
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if string(buf.Next(8)) != "\x89PNG\x0d\x0a\x1a\x0a" {
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f.err = fmt.Errorf("not a PNG buffer")
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return
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}
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// Read header chunk
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_ = buf.Next(4)
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if string(buf.Next(4)) != "IHDR" {
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f.err = fmt.Errorf("incorrect PNG buffer")
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return
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}
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w := f.readBeInt32(buf)
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h := f.readBeInt32(buf)
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bpc := f.readByte(buf)
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if bpc > 8 {
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f.err = fmt.Errorf("16-bit depth not supported in PNG file")
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}
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ct := f.readByte(buf)
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var colspace string
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var colorVal int
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colspace, colorVal = f.pngColorSpace(ct)
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if f.err != nil {
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return
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}
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if f.readByte(buf) != 0 {
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f.err = fmt.Errorf("'unknown compression method in PNG buffer")
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return
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}
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if f.readByte(buf) != 0 {
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f.err = fmt.Errorf("'unknown filter method in PNG buffer")
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return
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}
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if f.readByte(buf) != 0 {
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f.err = fmt.Errorf("interlacing not supported in PNG buffer")
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return
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}
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_ = buf.Next(4)
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dp := sprintf("/Predictor 15 /Colors %d /BitsPerComponent %d /Columns %d", colorVal, bpc, w)
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// Scan chunks looking for palette, transparency and image data
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pal := make([]byte, 0, 32)
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var trns []int
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data := make([]byte, 0, 32)
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loop := true
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for loop {
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n := int(f.readBeInt32(buf))
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// dbg("Loop [%d]", n)
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switch string(buf.Next(4)) {
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case "PLTE":
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// dbg("PLTE")
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// Read palette
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pal = buf.Next(n)
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_ = buf.Next(4)
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case "tRNS":
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// dbg("tRNS")
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// Read transparency info
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t := buf.Next(n)
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switch ct {
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case 0:
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trns = []int{int(t[1])} // ord(substr($t,1,1)));
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case 2:
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trns = []int{int(t[1]), int(t[3]), int(t[5])} // array(ord(substr($t,1,1)), ord(substr($t,3,1)), ord(substr($t,5,1)));
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default:
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pos := strings.Index(string(t), "\x00")
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if pos >= 0 {
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trns = []int{pos} // array($pos);
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}
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}
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_ = buf.Next(4)
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case "IDAT":
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// dbg("IDAT")
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// Read image data block
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data = append(data, buf.Next(n)...)
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_ = buf.Next(4)
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case "IEND":
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// dbg("IEND")
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loop = false
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case "pHYs":
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// dbg("pHYs")
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// png files theoretically support different x/y dpi
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// but we ignore files like this
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// but if they're the same then we can stamp our info
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// object with it
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x := int(f.readBeInt32(buf))
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y := int(f.readBeInt32(buf))
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units := buf.Next(1)[0]
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// fmt.Printf("got a pHYs block, x=%d, y=%d, u=%d, readdpi=%t\n",
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// x, y, int(units), readdpi)
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// only modify the info block if the user wants us to
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if x == y && readdpi {
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switch units {
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// if units is 1 then measurement is px/meter
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case 1:
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info.dpi = float64(x) / 39.3701 // inches per meter
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default:
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info.dpi = float64(x)
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}
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}
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_ = buf.Next(4)
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default:
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// dbg("default")
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_ = buf.Next(n + 4)
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}
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if loop {
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loop = n > 0
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}
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}
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if colspace == "Indexed" && len(pal) == 0 {
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f.err = fmt.Errorf("missing palette in PNG buffer")
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}
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info.w = float64(w)
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info.h = float64(h)
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info.cs = colspace
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info.bpc = int(bpc)
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info.f = "FlateDecode"
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info.dp = dp
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info.pal = pal
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info.trns = trns
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// dbg("ct [%d]", ct)
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if ct >= 4 {
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// Separate alpha and color channels
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var err error
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data, err = sliceUncompress(data)
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if err != nil {
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f.err = err
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return
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}
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var color, alpha bytes.Buffer
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if ct == 4 {
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// Gray image
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width := int(w)
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height := int(h)
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length := 2 * width
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var pos, elPos int
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for i := 0; i < height; i++ {
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pos = (1 + length) * i
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color.WriteByte(data[pos])
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alpha.WriteByte(data[pos])
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elPos = pos + 1
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for k := 0; k < width; k++ {
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color.WriteByte(data[elPos])
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alpha.WriteByte(data[elPos+1])
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elPos += 2
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}
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}
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} else {
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// RGB image
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width := int(w)
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height := int(h)
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length := 4 * width
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var pos, elPos int
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for i := 0; i < height; i++ {
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pos = (1 + length) * i
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color.WriteByte(data[pos])
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alpha.WriteByte(data[pos])
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elPos = pos + 1
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for k := 0; k < width; k++ {
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color.Write(data[elPos : elPos+3])
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alpha.WriteByte(data[elPos+3])
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elPos += 4
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}
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}
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}
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data = sliceCompress(color.Bytes())
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info.smask = sliceCompress(alpha.Bytes())
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if f.pdfVersion < "1.4" {
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f.pdfVersion = "1.4"
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}
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}
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info.data = data
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return
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}
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