mirror of
https://github.com/unidoc/unipdf.git
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58 lines
1.6 KiB
Go
58 lines
1.6 KiB
Go
/*
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* This file is subject to the terms and conditions defined in
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* file 'LICENSE.md', which is part of this source code package.
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*/
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package cmap
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import (
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"unicode/utf16"
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"github.com/unidoc/unipdf/v3/common"
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)
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// hexToCharCode returns the integer that is encoded in `shex` as a big-endian hex value
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func hexToCharCode(shex cmapHexString) CharCode {
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code := CharCode(0)
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for _, v := range shex.b {
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code <<= 8
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code |= CharCode(v)
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}
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return code
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}
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// hexToString decodes the UTF-16BE encoded string `shex` to unicode runes.
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// 9.10.3 ToUnicode CMaps (page 293)
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// • It shall use the beginbfchar, endbfchar, beginbfrange, and endbfrange operators to define the
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// mapping from character codes to Unicode character sequences expressed in UTF-16BE encoding.
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func hexToRunes(shex cmapHexString) []rune {
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if len(shex.b) == 1 {
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return []rune{rune(shex.b[0])}
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}
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b := shex.b
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if len(b)%2 != 0 {
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b = append(b, 0)
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common.Log.Debug("ERROR: hexToRunes. Padding shex=%#v to %+v", shex, b)
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}
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n := len(b) >> 1
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chars := make([]uint16, n)
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for i := 0; i < n; i++ {
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chars[i] = uint16(b[i<<1])<<8 + uint16(b[i<<1+1])
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}
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runes := utf16.Decode(chars)
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return runes
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}
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// hexToRune is the same as hexToRunes but expects only a single rune to be decoded.
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func hexToRune(shex cmapHexString) rune {
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runes := hexToRunes(shex)
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if n := len(runes); n == 0 {
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common.Log.Debug("ERROR: hexToRune. Expected at least one rune shex=%#v", shex)
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return MissingCodeRune
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}
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if len(runes) > 1 {
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common.Log.Debug("ERROR: hexToRune. Expected exactly one rune shex=%#v -> %#v", shex, runes)
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}
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return runes[0]
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}
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