japanese-drum-game/public/src/js/canvascache.js

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JavaScript
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class CanvasCache{
constructor(noSmoothing, w, h, scale){
this.noSmoothing = noSmoothing
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if(w){
this.resize(w, h, scale)
}
}
resize(w, h, scale){
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if(this.canvas){
this.map.clear()
}else{
this.map = new Map()
this.canvas = document.createElement("canvas")
this.ctx = this.canvas.getContext("2d")
if(this.noSmoothing){
this.ctx.imageSmoothingEnabled = false
}
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}
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this.scale = scale
this.x = 0
this.y = 0
this.w = w
this.h = h
this.lastW = 0
this.lastH = 0
this.canvas.width = this.w * this.scale
this.canvas.height = this.h * this.scale
this.ctx.scale(this.scale, this.scale)
}
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get(config, callback, setOnly){
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var img = this.map.get(config.id)
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if(img && setOnly || !img && !callback){
return
}
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var saved = false
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var time = Date.now()
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if(!img){
var w = config.w
var h = config.h
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this.x += this.lastW + (this.lastW ? 1 : 0)
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if(this.x + w > this.w){
this.x = 0
this.y += this.lastH + 1
}
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if(this.y + h > this.h){
var clear = true
var oldest = {time: time}
this.map.forEach((oldImg, id) => {
if(oldImg.time < oldest.time){
oldest.id = id
oldest.time = oldImg.time
}
})
var oldImg = this.map.get(oldest.id)
this.map.delete(oldest.id)
img = {
x: oldImg.x,
y: oldImg.y,
w: w,
h: h
}
}else{
var clear = false
this.lastW = w
this.lastH = Math.max(this.lastH, h)
img = {
x: this.x,
y: this.y,
w: w,
h: h
}
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}
saved = true
this.ctx.save()
this.ctx.translate(img.x |0, img.y |0)
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if(clear){
this.ctx.clearRect(0, 0, (img.w |0) + 1, (img.h |0) + 1)
}
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this.ctx.beginPath()
this.ctx.rect(0, 0, img.w |0, img.h |0)
this.ctx.clip()
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this.map.set(config.id, img)
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callback(this.ctx)
}
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img.time = time
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if(setOnly){
this.ctx.restore()
return
}
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var z = this.scale
config.ctx.drawImage(this.canvas,
img.x * z |0, img.y * z |0, img.w * z |0, img.h * z |0,
config.x |0, config.y |0, config.w |0, config.h |0
)
if(saved){
this.ctx.restore()
}
}
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set(config, callback){
return this.get(config, callback, true)
}
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clear(){
this.x = 0
this.y = 0
this.lastW = 0
this.lastH = 0
this.map.clear()
this.ctx.clearRect(0, 0, this.w, this.h)
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}
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clean(){
if(!this.canvas){
return
}
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this.resize(1, 1, 1)
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delete this.map
delete this.ctx
delete this.canvas
}
}