Custom anchor dates for relative date filter for a page

[deepguptaac]

Hi folks, 

I am preparing a sales report in which I need week on week progress of sales. In this report, I want to show sales of last 12 weeks which can be achived by using relative date filter for the page.

However in my case I want to add a slicer by which custom date can be selected and user can see weekly progression of sales of last 12 weeks from that selected slicer.

Please help me in case there is a easy solution for such.

Sample of final report is as in the picture.

[amitchandak]

@deepguptaac , if you select a date an then want 12 week trend, the slicer need to be on an independent table

//Date1 is independent Date table, Date is joined with Table
new measure =
var _max = maxx(allselected(Date1),Date1[Date])
var _min = _max -weekday(_max,2) + 1  -12*7
return
calculate( sum(Table[Value]), filter('Date', 'Date'[Date] >=_min && 'Date'[Date] <=_max))

Need of an Independent Date Table:https://www.youtube.com/watch?v=44fGGmg9fHI

Power BI — Week on Week and WTD
https://medium.com/@amitchandak.1978/power-bi-wtd-questions-time-intelligence-4-5-98c30fab69d3
https://community.powerbi.com/t5/Community-Blog/Week-Is-Not-So-Weak-WTD-Last-WTD-and-This-Week-vs-La...
https://www.youtube.com/watch?v=pnAesWxYgJ8