mirror of
https://github.com/unidoc/unipdf.git
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122 lines
3.7 KiB
Go
122 lines
3.7 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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"fmt"
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"github.com/unidoc/unidoc/common"
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"github.com/unidoc/unidoc/pdf/core"
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)
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// IdentityEncoder represents an 2-byte identity encoding
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type IdentityEncoder struct {
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baseName string
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}
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// NewIdentityTextEncoder returns a new IdentityEncoder based on predefined
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// encoding `baseName` and difference map `differences`.
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func NewIdentityTextEncoder(baseName string) IdentityEncoder {
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return IdentityEncoder{baseName}
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}
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// String returns a string that describes `enc`.
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func (enc IdentityEncoder) String() string {
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return enc.baseName
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}
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// Encode converts the Go unicode string `raw` to a PDF encoded string.
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func (enc IdentityEncoder) Encode(raw string) []byte {
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// runes -> character codes -> bytes
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var encoded bytes.Buffer
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for _, r := range raw {
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code, ok := enc.RuneToCharcode(r)
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if !ok {
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common.Log.Debug("Failed to map rune to charcode. rune=%+q", r)
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continue
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}
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// Each entry represented by 2 bytes.
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encoded.WriteByte(byte((code & 0xff00) >> 8))
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encoded.WriteByte(byte(code & 0xff))
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}
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return encoded.Bytes()
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}
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// CharcodeToGlyph returns the glyph name matching character code `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 IdentityEncoder) CharcodeToGlyph(code uint16) (string, bool) {
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r, found := enc.CharcodeToRune(code)
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if found && r == 0x20 {
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return "space", true
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}
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// Returns "uniXXXX" format where XXXX is the code in hex format.
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glyph := fmt.Sprintf("uni%.4X", code)
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return glyph, true
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}
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// GlyphToCharcode returns the character code matching glyph `glyph`.
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// The bool return flag is true if there was a match, and false otherwise.
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func (enc IdentityEncoder) GlyphToCharcode(glyph string) (uint16, bool) {
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// String with "uniXXXX" format where XXXX is the hexcode.
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if len(glyph) == 7 && glyph[0:3] == "uni" {
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var unicode uint16
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n, err := fmt.Sscanf(glyph, "uni%X", &unicode)
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if n == 1 && err == nil {
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return enc.RuneToCharcode(rune(unicode))
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}
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}
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common.Log.Debug("Symbol encoding error: unable to find glyph->charcode entry (%s)", glyph)
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return 0, false
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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 IdentityEncoder) RuneToCharcode(r rune) (uint16, bool) {
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return uint16(r), 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 IdentityEncoder) CharcodeToRune(code uint16) (rune, bool) {
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return rune(code), true
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}
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// RuneToGlyph returns the glyph name for rune `r`.
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// The bool return flag is true if there was a match, and false otherwise.
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func (enc IdentityEncoder) RuneToGlyph(r rune) (string, bool) {
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if r == 0x20 {
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return "space", true
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}
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glyph := fmt.Sprintf("uni%.4X", r)
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return glyph, true
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}
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// GlyphToRune returns the rune corresponding to glyph name `glyph`.
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// The bool return flag is true if there was a match, and false otherwise.
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func (enc IdentityEncoder) GlyphToRune(glyph string) (rune, bool) {
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// String with "uniXXXX" format where XXXX is the hexcode.
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if len(glyph) == 7 && glyph[0:3] == "uni" {
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unicode := uint16(0)
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n, err := fmt.Sscanf(glyph, "uni%X", &unicode)
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if n == 1 && err == nil {
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return rune(unicode), true
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}
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}
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return 0, false
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}
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// ToPdfObject returns a nil as it is not truly a PDF object and should not be attempted to store in file.
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func (enc IdentityEncoder) 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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