Anyhow, tl; dr: Canada is most certainly independent, and gained its independence peacefully (although there were minor conflicts prior to that).
The Crown is the head of our State; all authority derives from our Sovereign.
http://www.parl.gc.ca/About/House/compendium/web-content/c_d...
Ultimately, all legislation requires Royal Assent, and all executive powers are granted by the authority of the Sovereign, who may revoke them at their will and so force an election.
Would you say UK is not _actually_ independent because it's a constitutional monarchy? If not so, why would Canada be any different?
http://www.parl.gc.ca/About/House/compendium/web-content/c_d...
Yes, Canada is a monarchy, yes, the Queen has the ultimate power in theory, but the head of state is the Queen of Canada, not the Queen of the UK.
I'll repeat myself, them being both the same person is incidental, if you think the fact Canada being a monarchy means it's not independent, does that also mean the UK is not?
You can call out the native issue as in the case of Brazil, but then you doom any possible future state to a "violent birth" just by virtue of some cromagnon somewhere beating the last neanderthal to death to establish Homo Sapiens dominion on the planet.
And in any case, so what if every state so far has had a violent birth? Are we doomed forever to repeat the same paradigm?