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text: Add CacheGlyphs

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Fixes #1413
This commit is contained in:
Hajime Hoshi 2020-11-03 17:12:49 +09:00
parent ec6821b1e1
commit 2d9e2a0483
1 changed files with 31 additions and 9 deletions
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40
text/text.go
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@ -28,6 +28,7 @@ import (
"github.com/hajimehoshi/ebiten/v2" "github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/internal/colormcache" "github.com/hajimehoshi/ebiten/v2/internal/colormcache"
"github.com/hajimehoshi/ebiten/v2/internal/hooks"
) )
var ( var (
@ -35,10 +36,16 @@ var (
) )
func now() int64 { func now() int64 {
monotonicClock++
return monotonicClock return monotonicClock
} }
func init() {
hooks.AppendHookOnBeforeUpdate(func() error {
monotonicClock++
return nil
})
}
func fixed26_6ToFloat64(x fixed.Int26_6) float64 { func fixed26_6ToFloat64(x fixed.Int26_6) float64 {
return float64(x>>6) + float64(x&((1<<6)-1))/float64(1<<6) return float64(x>>6) + float64(x&((1<<6)-1))/float64(1<<6)
} }
@ -204,19 +211,20 @@ func Draw(dst *ebiten.Image, text string, face font.Face, x, y int, clr color.Co
prevR = r prevR = r
} }
const cacheLimit = 512 // cacheSoftLimit indicates the soft limit of the number of glyphs in the cache.
// If the number of glyphs exceeds this soft limits, old glyphs are removed.
// Even after clearning up the cache, the number of glyphs might still exceeds the soft limit, but
// this is fine.
const cacheSoftLimit = 512
// Clean up the cache. // Clean up the cache.
for len(glyphImageCache[face]) > cacheLimit { if len(glyphImageCache[face]) > cacheSoftLimit {
oldest := int64(math.MaxInt64)
oldestKey := rune(-1)
for r, e := range glyphImageCache[face] { for r, e := range glyphImageCache[face] {
if e.atime < oldest { // 60 is an arbitrary number.
oldestKey = r if e.atime < now()-60 {
oldest = e.atime delete(glyphImageCache[face], r)
} }
} }
delete(glyphImageCache[face], oldestKey)
} }
} }
@ -275,3 +283,17 @@ func BoundString(face font.Face, text string) image.Rectangle {
int(math.Ceil(fixed26_6ToFloat64(bounds.Max.Y))), int(math.Ceil(fixed26_6ToFloat64(bounds.Max.Y))),
) )
} }
// CacheGlyphs precaches the glyphs for the given text and the given font face into the cache.
//
// Draw automatically creates and caches necessary glyphs, so usually you don't have to call CacheGlyphs
// explicitly. However, for example, when you call Draw for each rune of one big text, Draw tries to create the glyph
// cache and render it for each rune. This is very innefficient because creating a glyph image and rendering it are
// different operations and can never be merged as one draw calls. CacheGlyphs creates necessary glyphs without
// rendering them, and these operations are likely merged into one draw call.
func CacheGlyphs(face font.Face, text string) {
textM.Lock()
defer textM.Unlock()
getGlyphImages(face, []rune(text))
}