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font/sfnt: support post table version 1.0

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Currently, the library produces a parsing error when the font
contains a PostScript table of version 1.0.

CL adds this version to the validation code and implements a glyph
name lookup for it.

Change-Id: Id4999d8b252e5c2d8e897f637ba31270336cfe9a
Reviewed-on: https://go-review.googlesource.com/c/146080
Reviewed-by: Nigel Tao <nigeltao@golang.org>
This commit is contained in:
Denys Smirnov 2018-10-31 00:12:18 +02:00 committed by Nigel Tao
parent 63626fb251
commit fe2fa19765
1 changed files with 38 additions and 19 deletions
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55
font/sfnt/sfnt.go
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@ -1165,6 +1165,8 @@ func (f *Font) parsePost(buf []byte, numGlyphs int32) (buf1 []byte, postTableVer
return nil, 0, err
}
switch u {
case 0x10000:
// No-op.
case 0x20000:
if f.post.length < headerSize+2+2*uint32(numGlyphs) {
return nil, 0, errInvalidPostTable
@ -1299,30 +1301,20 @@ func (f *Font) LoadGlyph(b *Buffer, x GlyphIndex, ppem fixed.Int26_6, opts *Load
return b.segments, nil
}
// GlyphName returns the name of the x'th glyph.
//
// Not every font contains glyph names. If not present, GlyphName will return
// ("", nil).
//
// If present, the glyph name, provided by the font, is assumed to follow the
// Adobe Glyph List Specification:
// https://github.com/adobe-type-tools/agl-specification/blob/master/README.md
//
// This is also known as the "Adobe Glyph Naming convention", the "Adobe
// document [for] Unicode and Glyph Names" or "PostScript glyph names".
//
// It returns ErrNotFound if the glyph index is out of range.
func (f *Font) GlyphName(b *Buffer, x GlyphIndex) (string, error) {
if int(x) >= f.NumGlyphs() {
func (f *Font) glyphNameFormat10(x GlyphIndex) (string, error) {
if x >= numBuiltInPostNames {
return "", ErrNotFound
}
if f.cached.postTableVersion != 0x20000 {
return "", nil
// https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html
i := builtInPostNamesOffsets[x+0]
j := builtInPostNamesOffsets[x+1]
return builtInPostNamesData[i:j], nil
}
func (f *Font) glyphNameFormat20(b *Buffer, x GlyphIndex) (string, error) {
if b == nil {
b = &Buffer{}
}
// The wire format for a Version 2 post table is documented at:
// https://www.microsoft.com/typography/otspec/post.htm
const glyphNameIndexOffset = 34
@ -1371,6 +1363,33 @@ func (f *Font) GlyphName(b *Buffer, x GlyphIndex) (string, error) {
}
}
// GlyphName returns the name of the x'th glyph.
//
// Not every font contains glyph names. If not present, GlyphName will return
// ("", nil).
//
// If present, the glyph name, provided by the font, is assumed to follow the
// Adobe Glyph List Specification:
// https://github.com/adobe-type-tools/agl-specification/blob/master/README.md
//
// This is also known as the "Adobe Glyph Naming convention", the "Adobe
// document [for] Unicode and Glyph Names" or "PostScript glyph names".
//
// It returns ErrNotFound if the glyph index is out of range.
func (f *Font) GlyphName(b *Buffer, x GlyphIndex) (string, error) {
if int(x) >= f.NumGlyphs() {
return "", ErrNotFound
}
switch f.cached.postTableVersion {
case 0x10000:
return f.glyphNameFormat10(x)
case 0x20000:
return f.glyphNameFormat20(b, x)
default:
return "", nil
}
}
// GlyphAdvance returns the advance width for the x'th glyph. ppem is the
// number of pixels in 1 em.
//