font/sfnt: implement {hh,vv}curveto.
Change-Id: I873f8b273d2fe9f39df7d333c36976f1b45239a0
Reviewed-on: https://go-review.googlesource.com/37917
Reviewed-by: David Crawshaw <crawshaw@golang.org>
diff --git a/font/sfnt/example_test.go b/font/sfnt/example_test.go
index f9a6697..1743156 100644
--- a/font/sfnt/example_test.go
+++ b/font/sfnt/example_test.go
@@ -38,6 +38,9 @@
log.Fatalf("GlyphIndex: no glyph index found for the rune 'G'")
}
segments, err := f.LoadGlyph(&b, x, fixed.I(ppem), nil)
+ if err != nil {
+ log.Fatalf("LoadGlyph: %v", err)
+ }
r := vector.NewRasterizer(width, height)
r.DrawOp = draw.Src
diff --git a/font/sfnt/postscript.go b/font/sfnt/postscript.go
index 8142bdc..ca1b831 100644
--- a/font/sfnt/postscript.go
+++ b/font/sfnt/postscript.go
@@ -566,8 +566,8 @@
23: {-1, "vstemhm", t2CStem},
24: {}, // rcurveline.
25: {}, // rlinecurve.
- 26: {}, // vvcurveto.
- 27: {}, // hhcurveto.
+ 26: {-1, "vvcurveto", t2CVvcurveto},
+ 27: {-1, "hhcurveto", t2CHhcurveto},
28: {}, // shortint.
29: {}, // callgsubr.
30: {-1, "vhcurveto", t2CVhcurveto},
@@ -770,6 +770,12 @@
// As per 5177.Type2.pdf section 4.1 "Path Construction Operators",
//
+// hhcurveto is:
+// - dy1 {dxa dxb dyb dxc}+
+//
+// vvcurveto is:
+// - dx1 {dya dxb dyb dyc}+
+//
// hvcurveto is one of:
// - dx1 dx2 dy2 dy3 {dya dxb dyb dxc dxd dxe dye dyf}* dxf?
// - {dxa dxb dyb dyc dyd dxe dye dxf}+ dyf?
@@ -778,59 +784,84 @@
// - dy1 dx2 dy2 dx3 {dxa dxb dyb dyc dyd dxe dye dxf}* dyf?
// - {dya dxb dyb dxc dxd dxe dye dyf}+ dxf?
-func t2CHvcurveto(p *psInterpreter) error { return t2CCurveto(p, false) }
-func t2CVhcurveto(p *psInterpreter) error { return t2CCurveto(p, true) }
+func t2CHhcurveto(p *psInterpreter) error { return t2CCurveto(p, false, false) }
+func t2CVvcurveto(p *psInterpreter) error { return t2CCurveto(p, false, true) }
+func t2CHvcurveto(p *psInterpreter) error { return t2CCurveto(p, true, false) }
+func t2CVhcurveto(p *psInterpreter) error { return t2CCurveto(p, true, true) }
-func t2CCurveto(p *psInterpreter, vertical bool) error {
+// t2CCurveto implements the hh / vv / hv / vh xxcurveto operators. N relative
+// cubic curve requires 6*N control points, but only 4*N+0 or 4*N+1 are used
+// here: all (or all but one) of the piecewise cubic curve's tangents are
+// implicitly horizontal or vertical.
+//
+// swap is whether that implicit horizontal / vertical constraint swaps as you
+// move along the piecewise cubic curve. If swap is false, the constraints are
+// either all horizontal or all vertical. If swap is true, it alternates.
+//
+// vertical is whether the first implicit constraint is vertical.
+func t2CCurveto(p *psInterpreter, swap, vertical bool) error {
if !p.type2Charstrings.seenWidth || p.stack.top < 4 {
return errInvalidCFFTable
}
- for i := int32(0); i != p.stack.top; vertical = !vertical {
- if vertical {
- i = t2CVcurveto(p, i)
- } else {
- i = t2CHcurveto(p, i)
+
+ i := int32(0)
+ switch p.stack.top & 3 {
+ case 0:
+ // No-op.
+ case 1:
+ if swap {
+ break
}
+ i = 1
+ if vertical {
+ p.type2Charstrings.x += p.stack.a[0]
+ } else {
+ p.type2Charstrings.y += p.stack.a[0]
+ }
+ default:
+ return errInvalidCFFTable
+ }
+
+ for i != p.stack.top {
+ i = t2CCurveto4(p, swap, vertical, i)
if i < 0 {
return errInvalidCFFTable
}
+ if swap {
+ vertical = !vertical
+ }
}
return nil
}
-func t2CHcurveto(p *psInterpreter, i int32) (j int32) {
+func t2CCurveto4(p *psInterpreter, swap bool, vertical bool, i int32) (j int32) {
if i+4 > p.stack.top {
return -1
}
dxa := p.stack.a[i+0]
- dxb := p.stack.a[i+1]
- dyb := p.stack.a[i+2]
- dyc := p.stack.a[i+3]
- dxc := int32(0)
- i += 4
- if i+1 == p.stack.top {
- dxc = p.stack.a[i]
- i++
- }
- t2CAppendCubeto(p, dxa, 0, dxb, dyb, dxc, dyc)
- return i
-}
-
-func t2CVcurveto(p *psInterpreter, i int32) (j int32) {
- if i+4 > p.stack.top {
- return -1
- }
- dya := p.stack.a[i+0]
+ dya := int32(0)
dxb := p.stack.a[i+1]
dyb := p.stack.a[i+2]
dxc := p.stack.a[i+3]
dyc := int32(0)
i += 4
- if i+1 == p.stack.top {
- dyc = p.stack.a[i]
- i++
+
+ if vertical {
+ dxa, dya = dya, dxa
}
- t2CAppendCubeto(p, 0, dya, dxb, dyb, dxc, dyc)
+
+ if swap {
+ if i+1 == p.stack.top {
+ dyc = p.stack.a[i]
+ i++
+ }
+ }
+
+ if swap != vertical {
+ dxc, dyc = dyc, dxc
+ }
+
+ t2CAppendCubeto(p, dxa, dya, dxb, dyb, dxc, dyc)
return i
}
diff --git a/font/sfnt/proprietary_test.go b/font/sfnt/proprietary_test.go
index b534a5b..b105ee5 100644
--- a/font/sfnt/proprietary_test.go
+++ b/font/sfnt/proprietary_test.go
@@ -186,6 +186,23 @@
}
}
+ for r, want := range proprietaryGlyphTestCases[qualifiedFilename] {
+ x, err := f.GlyphIndex(&buf, r)
+ if err != nil {
+ t.Errorf("GlyphIndex(%q): %v", r, err)
+ continue
+ }
+ got, err := f.LoadGlyph(&buf, x, ppem, nil)
+ if err != nil {
+ t.Errorf("LoadGlyph(%q): %v", r, err)
+ continue
+ }
+ if err := checkSegmentsEqual(got, want); err != nil {
+ t.Errorf("LoadGlyph(%q): %v", r, err)
+ continue
+ }
+ }
+
kernLoop:
for _, tc := range proprietaryKernTestCases[qualifiedFilename] {
var indexes [2]GlyphIndex
@@ -312,6 +329,113 @@
},
}
+// proprietaryGlyphTestCases hold a sample of each font's glyph vectors. The
+// numerical values can be verified by running the ttx tool, remembering that:
+// - for PostScript glyphs, ttx coordinates are relative, and hstem / vstem
+// operators are hinting-related and can be ignored.
+// - for TrueType glyphs, ttx coordinates are absolute, and consecutive
+// off-curve points implies an on-curve point at the midpoint.
+var proprietaryGlyphTestCases = map[string]map[rune][]Segment{
+ "adobe/SourceSansPro-Regular.otf": {
+ ',': {
+ // - contour #0
+ // 67 -170 rmoveto
+ moveTo(67, -170),
+ // 81 34 50 67 86 vvcurveto
+ cubeTo(148, -136, 198, -69, 198, 17),
+ // 60 -26 37 -43 -33 -28 -22 -36 -37 27 -20 32 3 4 0 1 3 vhcurveto
+ cubeTo(198, 77, 172, 114, 129, 114),
+ cubeTo(96, 114, 68, 92, 68, 56),
+ cubeTo(68, 19, 95, -1, 127, -1),
+ cubeTo(130, -1, 134, -1, 137, 0),
+ // 1 -53 -34 -44 -57 -25 rrcurveto
+ cubeTo(138, -53, 104, -97, 47, -122),
+ },
+ 'Q': {
+ // - contour #0
+ // 332 57 rmoveto
+ moveTo(332, 57),
+ // -117 -77 106 168 163 77 101 117 117 77 -101 -163 -168 -77 -106 -117 hvcurveto
+ cubeTo(215, 57, 138, 163, 138, 331),
+ cubeTo(138, 494, 215, 595, 332, 595),
+ cubeTo(449, 595, 526, 494, 526, 331),
+ cubeTo(526, 163, 449, 57, 332, 57),
+ // - contour #1
+ // 201 -222 rmoveto
+ moveTo(533, -165),
+ // 39 35 7 8 20 hvcurveto
+ cubeTo(572, -165, 607, -158, 627, -150),
+ // -16 64 rlineto
+ lineTo(611, -86),
+ // -5 -18 -22 -4 -29 hhcurveto
+ cubeTo(593, -91, 571, -95, 542, -95),
+ // -71 -60 29 58 -30 hvcurveto
+ cubeTo(471, -95, 411, -66, 381, -8),
+ // 139 24 93 126 189 vvcurveto
+ cubeTo(520, 16, 613, 142, 613, 331),
+ // 209 -116 128 -165 -165 -115 -127 -210 -193 96 -127 143 -20 vhcurveto
+ cubeTo(613, 540, 497, 668, 332, 668),
+ cubeTo(167, 668, 52, 541, 52, 331),
+ cubeTo(52, 138, 148, 11, 291, -9),
+ // -90 38 83 -66 121 hhcurveto
+ cubeTo(329, -99, 412, -165, 533, -165),
+ },
+ },
+
+ "microsoft/Arial.ttf": {
+ ',': {
+ // - contour #0
+ moveTo(182, 0),
+ lineTo(182, 205),
+ lineTo(387, 205),
+ lineTo(387, 0),
+ quadTo(387, -113, 347, -182),
+ quadTo(307, -252, 220, -290),
+ lineTo(170, -213),
+ quadTo(227, -188, 254, -139),
+ quadTo(281, -91, 284, 0),
+ lineTo(182, 0),
+ },
+ 'i': {
+ // - contour #0
+ moveTo(136, 1259),
+ lineTo(136, 1466),
+ lineTo(316, 1466),
+ lineTo(316, 1259),
+ lineTo(136, 1259),
+ // - contour #1
+ moveTo(136, 0),
+ lineTo(136, 1062),
+ lineTo(316, 1062),
+ lineTo(316, 0),
+ lineTo(136, 0),
+ },
+ 'o': {
+ // - contour #0
+ moveTo(68, 531),
+ quadTo(68, 826, 232, 968),
+ quadTo(369, 1086, 566, 1086),
+ quadTo(785, 1086, 924, 942),
+ quadTo(1063, 799, 1063, 546),
+ quadTo(1063, 341, 1001, 223),
+ quadTo(940, 106, 822, 41),
+ quadTo(705, -24, 566, -24),
+ quadTo(343, -24, 205, 119),
+ quadTo(68, 262, 68, 531),
+ // - contour #1
+ moveTo(253, 531),
+ quadTo(253, 327, 342, 225),
+ quadTo(431, 124, 566, 124),
+ quadTo(700, 124, 789, 226),
+ quadTo(878, 328, 878, 537),
+ quadTo(878, 734, 788, 835),
+ quadTo(699, 937, 566, 937),
+ quadTo(431, 937, 342, 836),
+ quadTo(253, 735, 253, 531),
+ },
+ },
+}
+
type kernTestCase struct {
ppem fixed.Int26_6
hinting font.Hinting
