pro qSkyImage_ChangeTimes, state, event
;+
; NAME:
;	qSkyImage_ChangeTimes
; PURPOSE:
;	Controls the units of the times (matrix start time and display time).
;	Units are either UT or modified Carrington variable.
; CATEGORY:
;	Widgets: qSkyImage
; CALLING SEQUENCE:
;	qSkyImage_ChangeTimes, state, event
; INPUTS:
;	state			array[1]; type: structure
;						qSkyImage state structure
;	event			array[1]; type: structure
;						event structure with event.id=state.wid_uttime or
;						state.wid_rotation
; OUTPUTS:
;	(updates values of state.wid_tmatrix and state.wid.tdisplay)
; CALLS:
;	Carrington, TimeGet, TimeSet, IsTime
; SIDE EFFECTS:
;	For a conversion from UT time to Carrington time, the calculation of the
;	UT time from the string stored in the value of the time widgets may fail.
;	If it does the fields are not updated.
; RESTRICTIONS:
; PROCEDURE:
;	The user value of state.wid_tlabel stores the information about which time units
;	are currently in use: it stores the widget ID of state.wid_uttime of state.wid_rotation.
;	If the event ID does not match this value and event.select=1 then the values
;	of both time widgets are converted to the new units, and the user value of
;	state.wid_tlabel is updated accordingly.
; STATE INFO USED:
;	widget_control, state.wid_tlabel  , get_uvalue=wid_unit
;	widget_control, state.wid_tmatrix , get_value=tmatrix, get_uvalue=format
;	widget_control, state.wid_tdisplay, get_value=tdisplay
; STATE INFO MODIFIED:
;	widget_control, event.id, set_button=event.select, set_uvalue=event.select
;	widget_control, state.wid_tmatrix , set_value=tmatrix
;	widget_control, state.wid_tdisplay, set_value=tdisplay
;	widget_control, state.wid_tlabel, set_uvalue=event.id
; MODIFICATION HISTORY:
;	MAY-2000, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
;-
on_error, 2							; On error, return to caller

COMPILE_OPT hidden

widget_control, event.id, set_button=event.select, set_uvalue=event.select

if event.select then begin
	widget_control, state.wid_tlabel  , get_uvalue=wid_unit

	if wid_unit ne event.id then begin
		widget_control, state.wid_tmatrix , get_value=tmatrix, get_uvalue=format
		widget_control, state.wid_tdisplay, get_value=tdisplay

		case event.id of
		state.wid_uttime: begin				; Rotation -> UT time
			tmatrix  = double(tmatrix )
			tdisplay = double(tdisplay)

			tmatrix  = Carrington(tmatrix )
			tdisplay = Carrington(tdisplay)

			tmatrix  = TimeGet(tmatrix , /ymd)
			tdisplay = TimeGet(tdisplay, /ymd)

			OK = 1B
		end
		state.wid_rotation: begin			; UT time -> Rotation
			tmatrix  = TimeSet(tmatrix )
			tdisplay = TimeSet(tdisplay)

			OK = IsTime(tmatrix) and IsTime(tdisplay)
			if OK then begin
				 tmatrix  = string( Carrington(tmatrix ), format=format )
				 tdisplay = string( Carrington(tdisplay), format=format )
			endif
		end
		endcase

		if OK then begin
			widget_control, state.wid_tmatrix , set_value=tmatrix
			widget_control, state.wid_tdisplay, set_value=tdisplay

			widget_control, state.wid_tlabel, set_uvalue=event.id
		endif
	endif
endif

return  &  end