"ctx.getImageDataHD" is not a thing

[Joncom]

This method doesn't actually exist. It's undefined...

Impact/lib/impact/impact.js

Line 214 in 66e872e

ig.normalizeVendorAttribute( ctx, 'getImageDataHD' );

Impact/lib/impact/impact.js

Lines 224 to 226 in 66e872e

	return (ratio === 1)
	? ctx.getImageData( x, y, width, height )
	: ctx.getImageDataHD( x, y, width, height );

[city41]

getImageDataHD is actually webkitGetImageDataHD and present on retina Apple devices.

https://developer.apple.com/documentation/webkitjs/canvasrenderingcontext2d/1633452-webkitgetimagedatahd

[phoboslab]

ig.normalizeVendorAttribute would have provided webkitGetImageDataHD as getImageDataHD on the ctx.

Safari used to automatically pixel double the internal resolution of the canvas on "retina" devices. I wrote an article about this whole ordeal back then.

However, this is all obsolete as far as I know. Safari it no longer does this. If you ask for a 320x240 Canvas, you now really get an internal resolution of 320x240. The backingStorePixelRatio is always 1. Same with all(?) other browsers. So the whole getImagePixels function could probably be simplified.