Note 14 - Capital Stock - Warrants Outstanding and Exercisable (Details) - $ / shares	9 Months Ended
	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020
Weighted Average Exercise Price (in dollars per share)	$ 1.90	$ 1.93	$ 1.92	$ 2.03
Number of Warrants Outstanding (in shares)	5,480,938	14,254,264	14,555,314	7,721,981
Weighted Average Remaining Contractual Life (Year)	1 year 186 days
Warrants 1 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 2.30
Number of Warrants Outstanding (in shares)	308,728
Weighted Average Remaining Contractual Life (Year)	1 year 102 days
Expiry Date	Aug. 09, 2022
Warrants 2 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.64
Number of Warrants Outstanding (in shares)	25,000
Weighted Average Remaining Contractual Life (Year)	2 years 21 days
Expiry Date	May 21, 2023
Warrants 3 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.80
Number of Warrants Outstanding (in shares)	4,965,392
Weighted Average Remaining Contractual Life (Year)	1 year 146 days
Expiry Date	Sep. 23, 2022
Warrants 4 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.83
Number of Warrants Outstanding (in shares)	181,818
Weighted Average Remaining Contractual Life (Year)	4 years 339 days
Expiry Date	Apr. 05, 2026