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Cache the glyph index lookup.

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benchmark                 old ns/op     new ns/op     delta
BenchmarkDrawString-8     8618239       8149527       -5.44%
This commit is contained in:
Nigel Tao 2015-08-31 14:14:50 +10:00
parent 03bdcc0fe1
commit 494079eb2b
1 changed files with 54 additions and 31 deletions
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85
truetype/face.go
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@ -151,39 +151,47 @@ func subPixels(q int) (value uint32, bias, mask fixed.Int26_6) {
return uint32(q), 32 / fixed.Int26_6(q), -64 / fixed.Int26_6(q)
}
// cacheEntry caches the arguments and return values of rasterize.
type cacheEntry struct {
key cacheKey
val cacheVal
// glyphCacheEntry caches the arguments and return values of rasterize.
type glyphCacheEntry struct {
key glyphCacheKey
val glyphCacheVal
}
type cacheKey struct {
type glyphCacheKey struct {
index Index
fx, fy uint8
}
type cacheVal struct {
type glyphCacheVal struct {
advanceWidth fixed.Int26_6
offset image.Point
gw int
gh int
}
type indexCacheEntry struct {
rune rune
index Index
}
// NewFace returns a new font.Face for the given Font.
func NewFace(f *Font, opts *Options) font.Face {
a := &face{
f: f,
hinting: opts.hinting(),
scale: fixed.Int26_6(0.5 + (opts.size() * opts.dpi() * 64 / 72)),
cache: make([]cacheEntry, opts.glyphCacheEntries()),
f: f,
hinting: opts.hinting(),
scale: fixed.Int26_6(0.5 + (opts.size() * opts.dpi() * 64 / 72)),
glyphCache: make([]glyphCacheEntry, opts.glyphCacheEntries()),
}
a.subPixelX, a.subPixelBiasX, a.subPixelMaskX = opts.subPixelsX()
a.subPixelY, a.subPixelBiasY, a.subPixelMaskY = opts.subPixelsY()
// Fill the cache with invalid entries. Valid cache entries have fx and fy
// in the range [0, 64).
for i := range a.cache {
a.cache[i].key.fy = 0xff
// Fill the cache with invalid entries. Valid glyph cache entries have fx
// and fy in the range [0, 64). Valid index cache entries have rune >= 0.
for i := range a.glyphCache {
a.glyphCache[i].key.fy = 0xff
}
for i := range a.indexCache {
a.indexCache[i].rune = -1
}
// Set the rasterizer's bounds to be big enough to handle the largest glyph.
@ -194,7 +202,7 @@ func NewFace(f *Font, opts *Options) font.Face {
ymax := -int(b.Min.Y-63) >> 6
a.maxw = xmax - xmin
a.maxh = ymax - ymin
a.masks = image.NewAlpha(image.Rect(0, 0, a.maxw, a.maxh*len(a.cache)))
a.masks = image.NewAlpha(image.Rect(0, 0, a.maxw, a.maxh*len(a.glyphCache)))
a.r.SetBounds(a.maxw, a.maxh)
a.p = facePainter{a}
@ -212,24 +220,39 @@ type face struct {
subPixelBiasY fixed.Int26_6
subPixelMaskY fixed.Int26_6
masks *image.Alpha
cache []cacheEntry
glyphCache []glyphCacheEntry
r raster.Rasterizer
p raster.Painter
paintOffset int
maxw int
maxh int
glyphBuf GlyphBuf
indexCache [indexCacheLen]indexCacheEntry
// TODO: clip rectangle?
}
const indexCacheLen = 256
func (a *face) index(r rune) Index {
const mask = indexCacheLen - 1
c := &a.indexCache[r&mask]
if c.rune == r {
return c.index
}
i := a.f.Index(r)
c.rune = r
c.index = i
return i
}
// Close satisfies the font.Face interface.
func (a *face) Close() error { return nil }
// Kern satisfies the font.Face interface.
func (a *face) Kern(r0, r1 rune) fixed.Int26_6 {
i0 := a.f.Index(r0)
i1 := a.f.Index(r1)
i0 := a.index(r0)
i1 := a.index(r1)
kern := a.f.Kern(a.scale, i0, i1)
if a.hinting != font.HintingNone {
kern = (kern + 32) &^ 63
@ -249,27 +272,27 @@ func (a *face) Glyph(dot fixed.Point26_6, r rune) (
ix, fx := int(dotX>>6), dotX&0x3f
iy, fy := int(dotY>>6), dotY&0x3f
index := a.f.Index(r)
index := a.index(r)
cIndex := uint32(index)
cIndex = cIndex*a.subPixelX - uint32(fx/a.subPixelMaskX)
cIndex = cIndex*a.subPixelY - uint32(fy/a.subPixelMaskY)
cIndex &= uint32(len(a.cache) - 1)
cIndex &= uint32(len(a.glyphCache) - 1)
a.paintOffset = a.maxh * int(cIndex)
k := cacheKey{
k := glyphCacheKey{
index: index,
fx: uint8(fx),
fy: uint8(fy),
}
var v cacheVal
if a.cache[cIndex].key != k {
var v glyphCacheVal
if a.glyphCache[cIndex].key != k {
var ok bool
v, ok = a.rasterize(index, fx, fy)
if !ok {
return image.Rectangle{}, nil, image.Point{}, 0, false
}
a.cache[cIndex] = cacheEntry{k, v}
a.glyphCache[cIndex] = glyphCacheEntry{k, v}
} else {
v = a.cache[cIndex].val
v = a.glyphCache[cIndex].val
}
dr.Min = image.Point{
@ -284,7 +307,7 @@ func (a *face) Glyph(dot fixed.Point26_6, r rune) (
}
func (a *face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
if err := a.glyphBuf.Load(a.f, a.scale, a.f.Index(r), a.hinting); err != nil {
if err := a.glyphBuf.Load(a.f, a.scale, a.index(r), a.hinting); err != nil {
return fixed.Rectangle26_6{}, 0, false
}
xmin := +a.glyphBuf.Bounds.Min.X
@ -307,7 +330,7 @@ func (a *face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.In
}
func (a *face) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
if err := a.glyphBuf.Load(a.f, a.scale, a.f.Index(r), a.hinting); err != nil {
if err := a.glyphBuf.Load(a.f, a.scale, a.index(r), a.hinting); err != nil {
return 0, false
}
return a.glyphBuf.AdvanceWidth, true
@ -317,9 +340,9 @@ func (a *face) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
// the width and height of the given glyph at the given sub-pixel offsets.
//
// The 26.6 fixed point arguments fx and fy must be in the range [0, 1).
func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v cacheVal, ok bool) {
func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v glyphCacheVal, ok bool) {
if err := a.glyphBuf.Load(a.f, a.scale, index, a.hinting); err != nil {
return cacheVal{}, false
return glyphCacheVal{}, false
}
// Calculate the integer-pixel bounds for the glyph.
xmin := int(fx+a.glyphBuf.Bounds.Min.X) >> 6
@ -327,7 +350,7 @@ func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v cacheVal, ok bool
xmax := int(fx+a.glyphBuf.Bounds.Max.X+0x3f) >> 6
ymax := int(fy-a.glyphBuf.Bounds.Min.Y+0x3f) >> 6
if xmin > xmax || ymin > ymax {
return cacheVal{}, false
return glyphCacheVal{}, false
}
// A TrueType's glyph's nodes can have negative co-ordinates, but the
// rasterizer clips anything left of x=0 or above y=0. xmin and ymin are
@ -346,7 +369,7 @@ func (a *face) rasterize(index Index, fx, fy fixed.Int26_6) (v cacheVal, ok bool
e0 = e1
}
a.r.Rasterize(a.p)
return cacheVal{
return glyphCacheVal{
a.glyphBuf.AdvanceWidth,
image.Point{xmin, ymin},
xmax - xmin,