mirror of
https://github.com/unidoc/unipdf.git
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5777ee1394
* Fixed filename:page in logging * Got CMap working for multi-rune entries * Treat CMap entries as strings instead of runes to handle multi-byte encodings. * Added a test for multibyte encoding. * Changed rune->CharCode maps to string->CharCode. * Removed unintentional changes. * Updated comments to match new function definitions. * Changed some []rune APIs to string * Fixes for reviewer comments.
124 lines
3.1 KiB
Go
124 lines
3.1 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 textencoding
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import (
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"bytes"
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"github.com/unidoc/unipdf/v3/core"
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"github.com/unidoc/unipdf/v3/internal/cmap"
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)
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// CMapEncoder encodes/decodes strings based on CMap mappings.
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type CMapEncoder struct {
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baseName string
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codeToCID *cmap.CMap
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cidToUnicode *cmap.CMap
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}
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// NewCMapEncoder returns a new CMapEncoder based on the predefined
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// encoding `baseName`. If `codeToCID` is nil, Identity encoding is assumed.
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// `cidToUnicode` must not be nil.
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func NewCMapEncoder(baseName string, codeToCID, cidToUnicode *cmap.CMap) CMapEncoder {
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return CMapEncoder{
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baseName: baseName,
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codeToCID: codeToCID,
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cidToUnicode: cidToUnicode,
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}
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}
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// Encode converts the Go unicode string to a PDF encoded string.
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func (enc CMapEncoder) Encode(str string) []byte {
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if enc.cidToUnicode == nil {
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return []byte{}
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}
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if enc.cidToUnicode.NBits() == 8 {
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return encodeString8bit(enc, str)
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}
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return encodeString16bit(enc, str)
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}
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// Decode converts PDF encoded string to a Go unicode string.
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func (enc CMapEncoder) Decode(raw []byte) string {
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if enc.codeToCID != nil {
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if codes, ok := enc.codeToCID.BytesToCharcodes(raw); ok {
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var buf bytes.Buffer
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for _, code := range codes {
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s, _ := enc.charcodeToString(CharCode(code))
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buf.WriteString(s)
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}
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return buf.String()
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}
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}
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return decodeString16bit(enc, raw)
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}
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// RuneToCharcode converts rune `r` to a PDF character code.
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// The bool return flag is true if there was a match, and false otherwise.
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func (enc CMapEncoder) RuneToCharcode(r rune) (CharCode, bool) {
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if enc.cidToUnicode == nil {
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return 0, false
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}
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// Map rune to CID.
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cid, ok := enc.cidToUnicode.StringToCID(string(r))
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if !ok {
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return 0, false
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}
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// Map CID to charcode. If charcode to CID CMap is nil, assume Identity encoding.
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if enc.codeToCID != nil {
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code, ok := enc.codeToCID.CIDToCharcode(cid)
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if !ok {
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return 0, false
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}
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return CharCode(code), true
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}
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return CharCode(cid), true
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}
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// CharcodeToRune converts PDF character code `code` to a rune.
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// The bool return flag is true if there was a match, and false otherwise.
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func (enc CMapEncoder) CharcodeToRune(code CharCode) (rune, bool) {
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s, ok := enc.charcodeToString(code)
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return ([]rune(s))[0], ok
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}
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func (enc CMapEncoder) charcodeToString(code CharCode) (string, bool) {
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if enc.cidToUnicode == nil {
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return MissingCodeString, false
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}
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// Map charcode to CID. If charcode to CID CMap is nil, assume Identity encoding.
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cid := cmap.CharCode(code)
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if enc.codeToCID != nil {
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var ok bool
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if cid, ok = enc.codeToCID.CharcodeToCID(cmap.CharCode(code)); !ok {
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return MissingCodeString, false
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}
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}
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// Map CID to rune.
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return enc.cidToUnicode.CharcodeToUnicode(cid)
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}
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// String returns a string that describes `enc`.
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func (enc CMapEncoder) String() string {
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return enc.baseName
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}
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// ToPdfObject returns a PDF Object that represents the encoding.
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func (enc CMapEncoder) ToPdfObject() core.PdfObject {
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if enc.baseName != "" {
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return core.MakeName(enc.baseName)
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}
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return core.MakeNull()
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}
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