Note 12 - Capital Stock - Continuity Schedule of Outstanding Share Purchase Warrants (Details) - $ / shares	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Balance, Number of Warrants (in shares)	30,923,489	19,676,560	13,953,872
Balance, Weighted Average Exercise Price (in dollars per share)	$ 1.97	$ 1.78	$ 1.65
Issued, Number of Warrants (in shares)	7,063,253	11,358,728	9,571,929
Issued, Weighted Average Exercise Price (in dollars per share)	$ 2.05	$ 2.30	$ 2
Exercised, Number of Warrants (in shares)	(3,999,881)	(61,799)	(1,989,717)
Exercised, Weighted Average Exercise Price (in dollars per share)	$ 1.21	$ 1.20	$ 1.20
Expired, Number of Warrants (in shares)	(3,542,951)	(50,000)	(1,859,524)
Expired, Weighted Average Exercise Price (in dollars per share)	$ 2.13	$ 1.95	$ 2.60
Exchanged for shares pursuant to Securities Exchange Agreement, Number of Warrants (in shares)	(11,000,000)
Exchanged for shares pursuant to Securities Exchange Agreement, Weighted Average Exercise Price (in dollars per share)	$ 2.30
Balance, Number of Warrants (in shares)	19,443,910	30,923,489	19,676,560
Balance, Weighted Average Exercise Price (in dollars per share)	$ 1.94	$ 1.97	$ 1.78