Shapes have fuzzy black outlines on stage

[fsih]

Expected Behavior

White shapes without outlines should have no outlines

Actual Behavior

White shapes have fuzzy black outlines on the stage

Steps to Reproduce

Draw some white things in the paint editor and observe them on the stage.
I think this is happening for non-white shapes too, it's just harder to tell

Operating System and Browser

Windows 10 Chrome

[cwillisf]

This might have to do with alpha blending (transparency) being processed twice: once when the SVG is being rasterized by scratch-svg-renderer's _draw method and again when drawn to the stage by _drawThese. I'm sure premultiplied alpha plays a role as well: the darkened pixels are probably being darkened by an amount proportional to their alpha value. See also: https://microsoft.github.io/Win2D/html/PremultipliedAlpha.htm

[cwillisf]

Another possibility: there may be a step in the rendering process where we need to clear to transparent white (RGBA = 1,1,1,0) rather than transparent black (RGBA = 0,0,0,0).

[gnarf]

@cwillisf - @mzgoddard and I suspect this might be a problem with premultiplied alpha also, maybe we update the blend mode to SRC_ALPHA and not premultiply like we did in the stamp routines?