mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 13:22:19 +02:00
97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
// Copyright 2020 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package colormcache
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import (
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"image/color"
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"math"
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"github.com/hajimehoshi/ebiten"
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)
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var (
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monotonicClock int64
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)
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func now() int64 {
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monotonicClock++
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return monotonicClock
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}
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const (
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cacheLimit = 512 // This is an arbitrary number.
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)
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type colorMCacheKey uint32
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type colorMCacheEntry struct {
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m ebiten.ColorM
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atime int64
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}
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var (
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colorMCache = map[colorMCacheKey]*colorMCacheEntry{}
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emptyColorM ebiten.ColorM
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)
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func init() {
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emptyColorM.Scale(0, 0, 0, 0)
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}
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func ColorToColorM(clr color.Color) ebiten.ColorM {
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// RGBA() is in [0 - 0xffff]. Adjust them in [0 - 0xff].
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cr, cg, cb, ca := clr.RGBA()
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cr /= 0x101
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cg /= 0x101
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cb /= 0x101
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ca /= 0x101
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if ca == 0 {
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return emptyColorM
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}
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key := colorMCacheKey(uint32(cr) | (uint32(cg) << 8) | (uint32(cb) << 16) | (uint32(ca) << 24))
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e, ok := colorMCache[key]
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if ok {
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e.atime = now()
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return e.m
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}
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if len(colorMCache) > cacheLimit {
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oldest := int64(math.MaxInt64)
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oldestKey := colorMCacheKey(0)
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for key, c := range colorMCache {
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if c.atime < oldest {
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oldestKey = key
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oldest = c.atime
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}
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}
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delete(colorMCache, oldestKey)
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}
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cm := ebiten.ColorM{}
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rf := float64(cr) / float64(ca)
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gf := float64(cg) / float64(ca)
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bf := float64(cb) / float64(ca)
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af := float64(ca) / 0xff
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cm.Scale(rf, gf, bf, af)
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e = &colorMCacheEntry{
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m: cm,
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atime: now(),
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}
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colorMCache[key] = e
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return e.m
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}
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