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freetype/truetype: fix IUP rounding for negative numbers. 

We now match Freetype C exactly for hinting luxisr.ttf. Yay.

R=bsiegert
CC=golang-dev
https://codereview.appspot.com/14336044
This commit is contained in:
Nigel Tao 2013-10-04 08:30:53 +10:00
parent 7e90529703
commit 0ec7c0ecae
2 changed files with 36 additions and 31 deletions
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60
freetype/truetype/hint.go
View File

@ -1108,36 +1108,48 @@ func (h *Hinter) iupInterp(interpY bool, p1, p2, ref1, ref2 int) {
h.points[glyphZone][current][i].X = xy
}
}
return
}
} else {
scale, scaleOK := int64(0), false
for i := p1; i <= p2; i++ {
if interpY {
xy = h.points[glyphZone][unhinted][i].Y
ifuXY = h.points[glyphZone][inFontUnits][i].Y
} else {
xy = h.points[glyphZone][unhinted][i].X
ifuXY = h.points[glyphZone][inFontUnits][i].X
}
scale, scaleOK := int64(0), false
for i := p1; i <= p2; i++ {
if interpY {
xy = h.points[glyphZone][unhinted][i].Y
ifuXY = h.points[glyphZone][inFontUnits][i].Y
} else {
xy = h.points[glyphZone][unhinted][i].X
ifuXY = h.points[glyphZone][inFontUnits][i].X
}
if xy <= unh1 {
xy += delta1
} else if xy >= unh2 {
xy += delta2
} else {
if !scaleOK {
scaleOK = true
denom := int64(ifu2 - ifu1)
scale = (int64(unh2+delta2-unh1-delta1)*0x10000 + denom/2) / denom
if xy <= unh1 {
xy += delta1
} else if xy >= unh2 {
xy += delta2
} else {
if !scaleOK {
scaleOK = true
numer := int64(unh2+delta2-unh1-delta1) * 0x10000
denom := int64(ifu2 - ifu1)
if numer >= 0 {
numer += denom / 2
} else {
numer -= denom / 2
}
xy = unh1 + delta1 + int32((int64(ifuXY-ifu1)*scale+0x8000)/0x10000)
scale = numer / denom
}
if interpY {
h.points[glyphZone][current][i].Y = xy
numer := int64(ifuXY-ifu1) * scale
if numer >= 0 {
numer += 0x8000
} else {
h.points[glyphZone][current][i].X = xy
numer -= 0x8000
}
xy = unh1 + delta1 + int32(numer/0x10000)
}
if interpY {
h.points[glyphZone][current][i].Y = xy
} else {
h.points[glyphZone][current][i].X = xy
}
}
}

7
freetype/truetype/truetype_test.go
View File

@ -114,13 +114,6 @@ func testScaling(t *testing.T, filename string, hinter *Hinter) {
const fontSize = 12
glyphBuf := NewGlyphBuf()
for i, want := range wants {
// TODO: completely implement hinting. For now, only the first N glyphs
// of luxisr.ttf are correctly hinted.
const N = 136
if hinter != nil && i == N {
break
}
if err = glyphBuf.Load(font, fontSize*64, Index(i), hinter); err != nil {
t.Fatalf("Load: %v", err)
}