def get_end_point(
scroll: Gtk.ScrolledWindow,
target: Gtk.Widget) -> int:
talloc = target.get_allocation()
adjustment = scroll.get_vadjustment()
start_point = adjustment.get_value()
page_size = adjustment.get_page_size()
if start_point <= talloc.y \
and (talloc.y+talloc.height) <= (start_point+page_size):
# If all parts of the target widget content are visible,
# no need to animate the scroll.
return -1
else:
if talloc.y > start_point:
# If the height of the target widget is greater than the
# height of its container, scroll to the top-left
# coordinates of the widget. Otherwise, scroll to the
# bottom-right coordinates of the widget.
if talloc.height > page_size:
end_point = talloc.y
else:
end_point = min(adjustment.get_upper()-page_size,
talloc.y+talloc.height-page_size)
else:
end_point = talloc.y
return end_point
def at_the_end(widget: Gtk.ScrolledWindow) -> bool:
"""Determines if a Scrollbar in a GtkScrolledWindow is at the end.
Args:
widget (GtkScrolledWindow)
Returns:
bool: The return value is True if at the end, False if not.
"""
adj_v = widget.get_vadjustment()
max_scroll_pos = adj_v.get_upper() - adj_v.get_page_size()
return adj_v.get_value() == max_scroll_pos
def scroll_to(scroll: Gtk.ScrolledWindow,
target: Gtk.Widget,
duration: int = 600) -> bool:
"""Animate the scroll for duration in milliseconds."""
target = target.get_allocation()
adjustment = scroll.get_vadjustment()
start_point = adjustment.get_value()
page_size = adjustment.get_page_size()
if start_point <= target.y \
and (target.y+target.height) <= (start_point+page_size):
# If all parts of the target widget content are visible,
# no need to animate the scroll.
return False
else:
if target.y > start_point:
# If the height of the target widget is greater than the
# height of its container, scroll to the top-left coordinates
# of the widget. Otherwise, scroll to the bottom-right
# coordinates of the widget.
if target.height > page_size:
end_point = target.y
else:
end_point = min(adjustment.get_upper() - page_size,
target.y + target.height - page_size)
else:
end_point = target.y
# Stop the current animating when the same widget requested to be
# animated again before it has finished animating
scroll.end_point = end_point
frame_clock = scroll.get_frame_clock()
start_time = frame_clock.get_frame_time()
end_time = start_time + 1000 * duration
def animate(widget: Gtk.Widget, frame_clock: Gdk.FrameClock) -> bool:
current_time = frame_clock.get_frame_time()
if current_time < end_time \
and adjustment.get_value() != end_point \
and widget.end_point == end_point:
t = (current_time - start_time) / (end_time - start_time)
t = Animation.ease_out_cubic(t)
adjustment.set_value(start_point + t *
(end_point - start_point))
return GLib.SOURCE_CONTINUE
else:
return GLib.SOURCE_REMOVE
scroll.add_tick_callback(animate)
return False
def animate(
scroll: Gtk.ScrolledWindow,
frame_clock: Gdk.FrameClock,
target: Gtk.Widget) -> bool:
current_time = frame_clock.get_frame_time()
adjustment = scroll.get_vadjustment()
start_point = adjustment.get_value()
end_point = get_end_point(scroll, target)
if current_time < end_time \
and end_point != -1 \
and adjustment.get_value() != end_point:
t = (current_time-start_time) / (end_time-start_time)
t = Animation.ease_out_cubic(t)
adjustment.set_value(start_point + t*(end_point-start_point))
return GLib.SOURCE_CONTINUE
else:
scroll.anime_id = None
return GLib.SOURCE_REMOVE
def scroll_to_end(widget: Gtk.ScrolledWindow) -> bool:
"""Scrolls to the end of a GtkScrolledWindow.
Args:
widget (GtkScrolledWindow)
Returns:
bool: The return value is False so it can be used with GLib.idle_add.
"""
adj_v = widget.get_vadjustment()
if adj_v is None:
# This can happen when the Widget is already destroyed when called
# from GLib.idle_add
return False
max_scroll_pos = adj_v.get_upper() - adj_v.get_page_size()
adj_v.set_value(max_scroll_pos)
adj_h = widget.get_hadjustment()
adj_h.set_value(0)
return False