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freetype/truetype: implement GC and MD instructions.

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These instructions are found in Adobe Source Sans Pro fonts.

R=golang-dev, nigeltao, bsiegert
CC=golang-dev
https://codereview.appspot.com/16440043

Committer: Nigel Tao <nigeltao@golang.org>
This commit is contained in:
R?my Oudompheng 2013-10-24 20:17:56 +11:00
parent ab106efa01
commit 7bee3b6fe0
2 changed files with 32 additions and 5 deletions
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27
freetype/truetype/hint.go
View File

@ -627,6 +627,33 @@ func (h *Hinter) run(program []byte, pCurrent, pUnhinted, pInFontUnits []Point,
case opRCVT:
h.stack[top-1] = int32(h.getScaledCVT(h.stack[top-1]))
case opGC0, opGC1:
i := h.stack[top-1]
if opcode == opGC0 {
p := h.point(2, current, i)
h.stack[top-1] = int32(dotProduct(f26dot6(p.X), f26dot6(p.Y), h.gs.pv))
} else {
p := h.point(2, unhinted, i)
// Using dv as per C Freetype.
h.stack[top-1] = int32(dotProduct(f26dot6(p.X), f26dot6(p.Y), h.gs.dv))
}
case opMD0, opMD1:
top--
i, j := h.stack[top-1], h.stack[top]
if opcode == opMD1 {
p := h.point(0, current, i)
q := h.point(1, current, j)
h.stack[top-1] = int32(dotProduct(f26dot6(p.X-q.X), f26dot6(p.Y-q.Y), h.gs.pv))
} else {
// TODO: do we need to check (h.gs.zp[0] == 0 || h.gs.zp[1] == 0)
// as C Freetype does, similar to the MDRP instructions?
p := h.point(0, unhinted, i)
q := h.point(1, unhinted, j)
// Use dv for MD0 as in C Freetype.
h.stack[top-1] = int32(dotProduct(f26dot6(p.X-q.X), f26dot6(p.Y-q.Y), h.gs.dv))
}
case opMPPEM, opMPS:
if top >= len(h.stack) {
return errors.New("truetype: hinting: stack overflow")

10
freetype/truetype/opcodes.go
View File

@ -80,11 +80,11 @@ const (
opRS = 0x43 // Read Store
opWCVTP = 0x44 // Write Control Value Table in Pixel units
opRCVT = 0x45 // Read Control Value Table entry
opGC0 = 0x46
opGC1 = 0x47
opGC0 = 0x46 // Get Coordinate projected onto the projection vector
opGC1 = 0x47 // .
opSCFS = 0x48
opMD0 = 0x49
opMD1 = 0x4a
opMD0 = 0x49 // Measure Distance
opMD1 = 0x4a // .
opMPPEM = 0x4b // Measure Pixels Per EM
opMPS = 0x4c // Measure Point Size
opFLIPON = 0x4d // set the auto FLIP Boolean to ON
@ -275,7 +275,7 @@ var popCount = [256]uint8{
1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, // 0x10 - 0x1f
1, 1, 0, 2, 0, 1, 1, q, q, q, 2, 1, 1, 0, 1, 1, // 0x20 - 0x2f
0, 0, q, q, q, q, 1, 1, 1, 0, q, q, 0, 0, 2, 2, // 0x30 - 0x3f
0, 0, 2, 1, 2, 1, q, q, q, q, q, 0, 0, 0, 0, 0, // 0x40 - 0x4f
0, 0, 2, 1, 2, 1, 1, 1, q, 2, 2, 0, 0, 0, 0, 0, // 0x40 - 0x4f
2, 2, 2, 2, 2, 2, 1, 1, 1, 0, 2, 2, 1, q, 1, 1, // 0x50 - 0x5f
2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 0x60 - 0x6f
q, q, q, q, q, q, 1, 1, 2, 2, 0, q, 0, 0, 1, 1, // 0x70 - 0x7f