+ return
+ on_page_up_key: (e) ->
+ if @wrap2.scrollTop is 0
+ return unless @cursor?
+ new_cursor = first_cursor_position @tree
+ if new_cursor?
+ if new_cursor.n isnt @cursor.n or new_cursor.i isnt @cursor.i
+ @move_cursor new_cursor
+ return
+ if @cursor?
+ screen_y = @cursor.y - @wrap2.scrollTop
+ scroll_amount = @wrap2_height - breathing_room
+ @wrap2.scrollTop = Math.max 0, @wrap2.scrollTop - scroll_amount
+ if @cursor?
+ @move_cursor_into_view screen_y + @wrap2.scrollTop
+ on_page_down_key: (e) ->
+ lowest_scrollpos = @wrap2.scrollHeight - @wrap2_height
+ if @wrap2.scrollTop is lowest_scrollpos
+ return unless @cursor?
+ new_cursor = last_cursor_position @tree
+ if new_cursor?
+ if new_cursor.n isnt @cursor.n or new_cursor.i isnt @cursor.i
+ @move_cursor new_cursor
+ return
+ if @cursor?
+ screen_y = @cursor.y - @wrap2.scrollTop
+ scroll_amount = @wrap2_height - breathing_room
+ @wrap2.scrollTop = Math.min lowest_scrollpos, @wrap2.scrollTop + scroll_amount
+ if @cursor?
+ @move_cursor_into_view screen_y + @wrap2.scrollTop
+ return
+ move_cursor_into_view: (y_target) ->
+ return if y_target is @cursor.y
+ was = @cursor
+ y_min = @wrap2.scrollTop
+ unless @wrap2.scrollTop is 0
+ y_min += breathing_room
+ y_max = @wrap2.scrollTop + @wrap2_height
+ unless @wrap2.scrollTop is @wrap2.scrollHeight - @wrap2_height # downmost
+ y_max -= breathing_room
+ y_target = Math.min y_target, y_max
+ y_target = Math.max y_target, y_min
+ if y_target < @cursor.y
+ finder = find_up_cursor_position
+ far_enough = (cur, target_y) ->
+ return cur.y + cur.h <= target_y
+ else
+ finder = find_down_cursor_position
+ far_enough = (cur, y_target) ->
+ return cur.y >= y_target
+ loop
+ cur = finder @tree, was, @cursor_ideal_x
+ break unless cur?
+ break if far_enough cur, y_target
+ was = cur
+ if was is @cursor
+ was = null
+ if was?
+ if was.y + was.h > y_max
+ was = null
+ else if was.y < y_min
+ was = null
+ if cur?
+ if cur.y + cur.h > y_max
+ cur = null
+ else if cur.y < y_min
+ cur = null
+ if cur? and was?
+ # both valid, pick best
+ if cur.y < y_min
+ new_cursor = was
+ else if was.y + was.h > y_max
+ new_cursor = cur
+ else if cur.y - y_target < y_target - was.y
+ new_cursor = cur
+ else
+ new_cursor = was
+ else
+ new_cursor = was ? cur
+ if new_cursor?
+ saved_ideal_x = @cursor_ideal_x
+ @move_cursor new_cursor
+ @cursor_ideal_x = saved_ideal_x
+ return