scroll

Sets the values of automatic scrollbars. (This method has no effect on manual scrollbars.)

• (send a-canvas scroll h-value v-value) -> void
      h-value : real number in [0.0, 1.0] or #f
      v-value : real number in [0.0, 1.0] or #f

  If either argument is #f, the scrollbar value is not changed in the corresponding direction.

  The h-value and v-value arguments each specify a fraction of the scrollbar's movement. A 0.0 value sets the scrollbar to its left/top, while a 1.0 value sets the scrollbar to its right/bottom. A 0.5 value sets the scrollbar to its middle. In general, if the canvas's virtual size is v, its client size is c, and (> v c), then scrolling to p sets the view start to (floor (* p (- v c))).

  See also init-auto-scrollbarsand get-view-start.