mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-14 23:17:27 +01:00
104 lines
2.2 KiB
Go
104 lines
2.2 KiB
Go
// Copyright 2023 The Ebitengine 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 text
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import (
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"math"
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"sync"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/internal/hook"
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)
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var monotonicClock int64
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const infTime = math.MaxInt64
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func now() int64 {
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return monotonicClock
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}
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func init() {
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hook.AppendHookOnBeforeUpdate(func() error {
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monotonicClock++
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return nil
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})
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}
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type glyphImageCacheEntry struct {
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image *ebiten.Image
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atime int64
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}
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type glyphImageCache[Key comparable] struct {
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cache map[Key]*glyphImageCacheEntry
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atime int64
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glyphVariationCount int
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m sync.Mutex
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}
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func (g *glyphImageCache[Key]) getOrCreate(key Key, create func() *ebiten.Image) *ebiten.Image {
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g.m.Lock()
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defer g.m.Unlock()
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n := now()
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e, ok := g.cache[key]
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if ok {
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e.atime = n
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return e.image
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}
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if g.cache == nil {
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g.cache = map[Key]*glyphImageCacheEntry{}
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}
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img := create()
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e = &glyphImageCacheEntry{
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image: img,
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}
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if img != nil {
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e.atime = n
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} else {
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// If the glyph image is nil, the entry doesn't have to be removed.
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// Keep this until the face is GCed.
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e.atime = infTime
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}
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g.cache[key] = e
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// Clean up old entries.
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if g.atime < n {
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// cacheSoftLimit indicates the soft limit of the number of glyphs in the cache.
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// If the number of glyphs exceeds this soft limits, old glyphs are removed.
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// Even after cleaning up the cache, the number of glyphs might still exceed the soft limit, but
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// this is fine.
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cacheSoftLimit := 128 * g.glyphVariationCount
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if len(g.cache) > cacheSoftLimit {
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for key, e := range g.cache {
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// 60 is an arbitrary number.
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if e.atime >= now()-60 {
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continue
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}
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delete(g.cache, key)
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}
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}
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}
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g.atime = n
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return img
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}
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