Only alpha and premultiplied are truly canvas attributes. Alpha because it potentially affects the storage for the canvas pixels, although more than likely both RGB & RGBA canvases use 32 bpp, and premultiplied because it affects how those pixels are interpreted, as does alpha. Except for preserved, the rest of the attributes involve additional memory blocks that could easily be reused for drawing to a different canvas. Whether you need preserved depends on your drawing algorithms so it should rightly be considered a context attribute.This doesn't work for WebGL
var context = new WebGLRenderingContext();canvas1.setContext(context)
It's missing the creation attributes for the canvas (alpha? depth? stencil? anti-alias? preserved? premultiplied?)
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