font/sfnt,font/opentype: correct font height computation
According to https://www.freetype.org/freetype2/docs/glyphs/glyphs-3.html
the line spacing of a font is computed as
line space = ascent - descent + linegap
Use that formula to compute the Height field of a Font's Metrics.
Change-Id: I1c44eca9f662e0aae68716cd8859670fe0b394d7
Reviewed-on: https://go-review.googlesource.com/120815
Reviewed-by: Nigel Tao <nigeltao@golang.org>
diff --git a/font/opentype/face_test.go b/font/opentype/face_test.go
index 224b0f2..524a7f6 100644
--- a/font/opentype/face_test.go
+++ b/font/opentype/face_test.go
@@ -82,7 +82,7 @@
}
func TestFaceMetrics(t *testing.T) {
- want := font.Metrics{Height: 768, Ascent: 726, Descent: 162}
+ want := font.Metrics{Height: 888, Ascent: 726, Descent: 162}
got := regular.Metrics()
if got != want {
t.Fatalf("metrics failed. got=%#v. want=%#v", got, want)
diff --git a/font/sfnt/sfnt.go b/font/sfnt/sfnt.go
index cc4ceac..21a7927 100644
--- a/font/sfnt/sfnt.go
+++ b/font/sfnt/sfnt.go
@@ -1357,8 +1357,7 @@
// Metrics returns the metrics of this font.
func (f *Font) Metrics(b *Buffer, ppem fixed.Int26_6, h font.Hinting) (font.Metrics, error) {
m := font.Metrics{
- // TODO: is adding lineGap correct?
- Height: ppem + scale(fixed.Int26_6(f.cached.lineGap)*ppem, f.cached.unitsPerEm),
+ Height: scale(fixed.Int26_6(f.cached.ascent-f.cached.descent+f.cached.lineGap)*ppem, f.cached.unitsPerEm),
Ascent: +scale(fixed.Int26_6(f.cached.ascent)*ppem, f.cached.unitsPerEm),
Descent: -scale(fixed.Int26_6(f.cached.descent)*ppem, f.cached.unitsPerEm),
}
diff --git a/font/sfnt/sfnt_test.go b/font/sfnt/sfnt_test.go
index b9b66a7..ca52fba 100644
--- a/font/sfnt/sfnt_test.go
+++ b/font/sfnt/sfnt_test.go
@@ -223,9 +223,9 @@
font []byte
want font.Metrics
}{
- "goregular": {goregular.TTF, font.Metrics{Height: 2048, Ascent: 1935, Descent: 432}},
+ "goregular": {goregular.TTF, font.Metrics{Height: 2367, Ascent: 1935, Descent: 432}},
// cmapTest.ttf has a non-zero lineGap.
- "cmapTest": {cmapFont, font.Metrics{Height: 2232, Ascent: 1365, Descent: 0}},
+ "cmapTest": {cmapFont, font.Metrics{Height: 1549, Ascent: 1365, Descent: 0}},
}
var b Buffer
for name, tc := range testCases {
@@ -574,11 +574,11 @@
lineTo(136, 1297),
lineTo(136, 68),
}, {
- // .null
- // Empty glyph.
+ // .null
+ // Empty glyph.
}, {
- // nonmarkingreturn
- // Empty glyph.
+ // nonmarkingreturn
+ // Empty glyph.
}, {
// zero
// - contour #0
