If, 5 years from now, most Web developers have 200dpi screens so
browsers are using at least a 2:1 ratio for their canvas backing
stores, then putImageData and getImageData could be safely
introduced with the current spec, because an assumption that device
pixels are the same as canvas units would break immediately in
testing.
The problem is that you couldn't, if you waited for 5 years, you'd get
5 years of people developing on the assumption that there's a 1:1
ratio -- at that point you could no longer change the ratio as you
would break 5 years of sites, even those sites made by developers with
hidpi screens who had been trying to be correct -- because they would
not be able to test.
An example of this effect in html5 is the behaviour of transforms
during path transforms -- having path construction not be effected by
transforms would arguably be better than what html5 has ended up
doing, and the reason html5 does it the way it does is because firefox
and webkit have both been doing it that way for a number of years, and
there's already content that breaks if we change behaviour. (Ideally
there would be a distinct Path object that was not tied to the canvas,
the resolving this issue)
--Oliver
Rob
--
"He was pierced for our transgressions, he was crushed for our
iniquities; the punishment that brought us peace was upon him, and
by his wounds we are healed. We all, like sheep, have gone astray,
each of us has turned to his own way; and the LORD has laid on him
the iniquity of us all." [Isaiah 53:5-6]
