font/sfnt: support cmap format 12.

Change-Id: I2791f5aec860bbb16c6c6945703827afd55c11dc
Reviewed-on: https://go-review.googlesource.com/36291
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This commit is contained in:
Nigel Tao 2017-02-03 19:18:20 +11:00
parent 55ae12acc9
commit c8ab450c16
2 changed files with 79 additions and 17 deletions

View File

@ -80,7 +80,7 @@ var supportedCmapFormat = func(format, pid, psid uint16) bool {
case 4:
return true
case 12:
// TODO: implement.
return true
}
return false
}
@ -92,7 +92,7 @@ func (f *Font) makeCachedGlyphIndex(buf []byte, offset, length uint32, format ui
case 4:
return f.makeCachedGlyphIndexFormat4(buf, offset, length)
case 12:
// TODO: implement, including a cmapEntry32 type (32, not 16).
return f.makeCachedGlyphIndexFormat12(buf, offset, length)
}
panic("unreachable")
}
@ -196,6 +196,68 @@ func (f *Font) makeCachedGlyphIndexFormat4(buf []byte, offset, length uint32) ([
return buf, nil
}
func (f *Font) makeCachedGlyphIndexFormat12(buf []byte, offset, _ uint32) ([]byte, error) {
const headerSize = 16
if offset+headerSize > f.cmap.length {
return nil, errInvalidCmapTable
}
var err error
buf, err = f.src.view(buf, int(f.cmap.offset+offset), headerSize)
if err != nil {
return nil, err
}
offset += headerSize
length := u32(buf[4:])
numGroups := u32(buf[12:])
if f.cmap.length < offset || length > f.cmap.length-offset {
return nil, errInvalidCmapTable
}
if numGroups > maxCmapSegments {
return nil, errUnsupportedNumberOfCmapSegments
}
eLength := 12 * numGroups
if headerSize+eLength != length {
return nil, errInvalidCmapTable
}
buf, err = f.src.view(buf, int(f.cmap.offset+offset), int(eLength))
if err != nil {
return nil, err
}
offset += eLength
entries := make([]cmapEntry32, numGroups)
for i := range entries {
entries[i] = cmapEntry32{
start: u32(buf[0+12*i:]),
end: u32(buf[4+12*i:]),
delta: u32(buf[8+12*i:]),
}
}
f.cached.glyphIndex = func(f *Font, b *Buffer, r rune) (GlyphIndex, error) {
c := uint32(r)
for i, j := 0, len(entries); i < j; {
h := i + (j-i)/2
entry := &entries[h]
if c < entry.start {
j = h
} else if entry.end < c {
i = h + 1
} else {
return GlyphIndex(c - entry.start + entry.delta), nil
}
}
return 0, nil
}
return buf, nil
}
type cmapEntry16 struct {
end, start, delta, offset uint16
}
type cmapEntry32 struct {
start, end, delta uint32
}

View File

@ -94,7 +94,7 @@ func TestGlyphIndex(t *testing.T) {
t.Fatal(err)
}
for _, format := range []int{-1, 0, 4} {
for _, format := range []int{-1, 0, 4, 12} {
testGlyphIndex(t, data, format)
}
}
@ -158,9 +158,6 @@ func testGlyphIndex(t *testing.T, data []byte, cmapFormat int) {
{'\u4e2d', 12},
{'\u4e2e', 0},
/*
TODO: support runes above U+FFFF, i.e. cmap format 12.
{'\U0001f0a0', 0},
{'\U0001f0a1', 13},
{'\U0001f0a2', 0},
@ -169,15 +166,18 @@ func testGlyphIndex(t *testing.T, data []byte, cmapFormat int) {
{'\U0001f0b1', 14},
{'\U0001f0b2', 15},
{'\U0001f0b3', 0},
*/
}
var b Buffer
for _, tc := range testCases {
want := tc.want
// cmap format 0, with the Macintosh Roman encoding, can only represent
// a limited set of non-ASCII runes, e.g. U+00FF.
if cmapFormat == 0 && tc.r > '\u007f' && tc.r != '\u00ff' {
switch {
case cmapFormat == 0 && tc.r > '\u007f' && tc.r != '\u00ff':
// cmap format 0, with the Macintosh Roman encoding, can only
// represent a limited set of non-ASCII runes, e.g. U+00FF.
want = 0
case cmapFormat == 4 && tc.r > '\uffff':
// cmap format 4 only supports the Basic Multilingual Plane (BMP).
want = 0
}