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mirror of https://github.com/OpenDiablo2/OpenDiablo2 synced 2024-11-12 23:43:24 -05:00
OpenDiablo2/d2helper/ColorConvert.go
2019-11-10 03:36:53 -05:00

76 lines
1.4 KiB
Go

package d2helper
import (
"image/color"
"math"
"github.com/hajimehoshi/ebiten"
)
type colorMCacheKey uint32
type colorMCacheEntry struct {
m ebiten.ColorM
atime int64
}
var (
colorMCache = map[colorMCacheKey]*colorMCacheEntry{}
emptyColorM ebiten.ColorM
monotonicClock int64
cacheLimit = 512
)
func init() {
emptyColorM.Scale(0, 0, 0, 0)
}
func now() int64 {
monotonicClock++
return monotonicClock
}
// ColorToColorM converts a normal color to a color matrix
func ColorToColorM(clr color.Color) ebiten.ColorM {
// RGBA() is in [0 - 0xffff]. Adjust them in [0 - 0xff].
cr, cg, cb, ca := clr.RGBA()
cr >>= 8
cg >>= 8
cb >>= 8
ca >>= 8
if ca == 0 {
return emptyColorM
}
key := colorMCacheKey(uint32(cr) | (uint32(cg) << 8) | (uint32(cb) << 16) | (uint32(ca) << 24))
e, ok := colorMCache[key]
if ok {
e.atime = now()
return e.m
}
if len(colorMCache) > cacheLimit {
oldest := int64(math.MaxInt64)
oldestKey := colorMCacheKey(0)
for key, c := range colorMCache {
if c.atime < oldest {
oldestKey = key
oldest = c.atime
}
}
delete(colorMCache, oldestKey)
}
cm := ebiten.ColorM{}
rf := float64(cr) / float64(ca)
gf := float64(cg) / float64(ca)
bf := float64(cb) / float64(ca)
af := float64(ca) / 0xff
cm.Scale(rf, gf, bf, af)
e = &colorMCacheEntry{
m: cm,
atime: now(),
}
colorMCache[key] = e
return e.m
}