Scalable game canvas

public/src/js/scalablecanvas.js

@@ -0,0 +1,42 @@
+class ScalableCanvas{
+	constructor(id, width, height, noStyle){
+		var oldCanvas = document.getElementById(id)
+		if(oldCanvas){
+			this.canvas = oldCanvas
+		}else{
+			this.canvas = document.createElement("canvas")
+			this.canvas.id = id
+		}
+		this.ctx = this.canvas.getContext("2d")
+		this.rescale()
+		this.resize(width, height, noStyle)
+	}
+	resize(width, height, noStyle){
+		if(width != this.width || height != this.height){
+			this.width = width
+			this.height = height
+			this.scaledWidth = width * this.scale
+			this.canvas.width = this.scaledWidth
+			this.scaledHeight = height * this.scale
+			this.canvas.height = this.scaledHeight
+			if(noStyle || this.scale == 1){
+				if(this.canvas.style.width){
+					this.canvas.style.width = ""
+				}
+				if(this.canvas.style.height){
+					this.canvas.style.height = ""
+				}
+			}else{
+				this.canvas.style.width = width + "px"
+				this.canvas.style.height = height + "px"
+			}
+		}
+	}
+	rescale(){
+		var scale = window.devicePixelRatio || 1
+		if(scale != this.scale){
+			this.ctx.scale(scale, scale)
+			this.scale = scale
+		}
+	}
+}