Day Of Week Offset Does Not Work Correctly

[richardortiz84]

When attempting to set the dayOfWeekOffset to be Sunday like a typical work week calendar, I noticed that the start of the week would indeed be set to the given day, but the calendar then began 6 days in advance. For instance this month August 2024 setting the dayOfWeekOffset to Sunday resulted in a calendar having a first visible day of 7. If you turned on showPreviousMonthDays, the 3 days that show at the beginning of the calendar would be visually set to be the previous month, but would in fact be days from this month (4, 5, and 6).

My assumption is that setting this field would set the beginning of the week to be the given day but the months calendar would still begin on the 1st.

This seems to be because calculateVisibleDaysOfPreviousMonth and calculateVisibleDaysOfNextMonth do not take into account the offset and adjust the numbers accordingly.

Here is an update to those functions to account for the offset:

private fun calculateVisibleDaysOfPreviousMonth(
	monthYear: MonthYear,
	dayOfWeekOffset: Int,
): Int {
	val (month, year) = monthYear
	val dayOfWeekMonthBegins = LocalDate(year = year, month = month, dayOfMonth = 1).dayOfWeek.ordinal // Monday = 0

	return when {
		dayOfWeekOffset > dayOfWeekMonthBegins -> 7 - dayOfWeekOffset + dayOfWeekMonthBegins
		dayOfWeekOffset < dayOfWeekMonthBegins -> dayOfWeekMonthBegins - dayOfWeekOffset
		else -> 0
	}
}

private fun calculateVisibleDaysOfNextMonth(
	monthYear: MonthYear,
	dayOfWeekOffset: Int,
): Int {
	val (month, year) = monthYear
	val daysInMonth = monthLength(month, year)
	val dayOfWeekMonthEnds = LocalDate(year = year, month = month, dayOfMonth = daysInMonth).dayOfWeek.ordinal

	return when {
		dayOfWeekOffset > dayOfWeekMonthEnds -> dayOfWeekOffset - 1 - dayOfWeekMonthEnds
		dayOfWeekOffset < dayOfWeekMonthEnds -> 6 - (dayOfWeekMonthEnds - dayOfWeekOffset)
		else -> 6
	}
}

In CalendarView.kt in function private fun CalendarView()
Update the function calls in lines 73-77

	val previousMonthDays = calculateVisibleDaysOfPreviousMonth(yearMonth, config.value.dayOfWeekOffset)
	val nextMonthDays = if (config.value.showNextMonthDays) {
		calculateVisibleDaysOfNextMonth(yearMonth, config.value.dayOfWeekOffset)
	} else {
		0
	}

Delete Line 152 in function private fun Item()

	newDate = newDate.plus(state.dayOfWeekOffset, DateTimeUnit.DAY)

Here is the after:

[ismai117]

@WojciechOsak can you update this please?

[ismai117]

@richardortiz84 what else did you change? I updated those functions but now it's updated to

val startDate = LocalDate.today()
val config = rememberCalendarState(
	startDate = startDate,
	monthOffset = 0,
	dayOfWeekOffset = 6
)
CalendarView(
	config = config,
)

[richardortiz84]

@ismai117 My apologies I forgot that I had also modified the Item composable in the calendar view. I have updated my original comment but here is the additional changes.

In CalendarView.kt in function private fun CalendarView()
Update the function calls in lines 73-77

	val previousMonthDays = calculateVisibleDaysOfPreviousMonth(yearMonth, config.value.dayOfWeekOffset)
	val nextMonthDays = if (config.value.showNextMonthDays) {
		calculateVisibleDaysOfNextMonth(yearMonth, config.value.dayOfWeekOffset)
	} else {
		0
	}

Delete Line 152 in function private fun Item()

	newDate = newDate.plus(state.dayOfWeekOffset, DateTimeUnit.DAY)