Can I used DAX to determine the difference between two fields within a given time period

I have a dataset that shows the total hours for every work item, with one row for each time the work item is updated (this is max 1 per day). Here is some sample data:

I need a DAX expression showing the work item hours for each time period, with the intention of using this in a line chart with weekly increments on the x axis showing work that has been completed in that time period.

I have tried writing this myself and cannot seem to get it working correctly. This is my current attempt and I feel I am close - any help would be appreciated

    CompletedWorkDifference = 
SUMX (
    VALUES ( Task_Revisions[WorkItemId] ),
    VAR CurrentRowWorkItemId = Task_Revisions[WorkItemId]
    VAR CurrentRowChangedDate = Task_Revisions[ChangedDate]
    VAR PreviousCompletedWork =
        CALCULATE (
            LASTNONBLANK ( Task_Revisions[CompletedWork], 1 ),
            FILTER (
                ALL ( Task_Revisions ),
                Task_Revisions[WorkItemId] = CurrentRowWorkItemId
                    && Task_Revisions[ChangedDate] < CurrentRowChangedDate
            )
        )
    VAR CurrentCompletedWork = Task_Revisions[CompletedWork]
    RETURN
        IF ( PreviousCompletedWork <> BLANK (), CurrentCompletedWork - PreviousCompletedWork, BLANK () )
)

I was able to solve this with the following DAX, and joining to a date table that I had setup for the tasks

task_hours_by_time_period = 
SUMX(
    VALUES(task_revisions[WorkItemID]),
    CALCULATE(
        SUM(task_revisions[CompletedWork]),
        USERELATIONSHIP(task_revisions[ChangedDateSK], 'Task_Calendar'[DateSK]),
        FILTER(
            ALL('Task_Calendar'),
            'Task_Calendar'[Date] >= MIN('Task_Calendar'[Date]) &&
            'Task_Calendar'[Date] <= MAX('Task_Calendar'[Date])
        )
    ) - CALCULATE(
        SUM(task_revisions[CompletedWork]),
        USERELATIONSHIP(task_revisions[ChangedDateSK], 'Task_Calendar'[DateSK]),
        FILTER(
            ALL('Task_Calendar'),
            'Task_Calendar'[Date] < MIN('Task_Calendar'[Date])
        )
    )
)