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scroll-view: Add proper smooth scrolling

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The code here before was added as dummy code to satisfy an error
in the missing switch, and wasn't ever tested due to the lack of XI2
in mutter. Use the same math as GtkRange does to calculate scroll bar
positions from raw XI2 deltas to allow for proper smooth scrolling.

https://bugzilla.gnome.org/show_bug.cgi?id=687573
This commit is contained in:
Jasper St. Pierre 2012-11-04 10:10:50 -05:00
parent 36edff9e15
commit 06dc12e217
3 changed files with 66 additions and 36 deletions
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28
src/st/st-adjustment.c
View File

@ -566,3 +566,31 @@ st_adjustment_get_values (StAdjustment *adjustment,
*page_size = priv->page_size;
}
/**
* st_adjustment_adjust_for_scroll_event:
* @adjustment: An #StAdjustment
* @delta: A delta, retrieved directly from clutter_event_get_scroll_delta()
* or similar.
*
* Adjusts the adjustment using delta values from a scroll event.
* You should use this instead of using st_adjustment_set_value()
* as this method will tweak the values directly using the same
* math as GTK+, to ensure that scrolling is consistent across
* the environment.
*/
void
st_adjustment_adjust_for_scroll_event (StAdjustment *adjustment,
gdouble delta)
{
StAdjustmentPrivate *priv;
gdouble new_value, scroll_unit;
g_return_if_fail (ST_IS_ADJUSTMENT (adjustment));
priv = adjustment->priv;
scroll_unit = pow (priv->page_size, 2.0 / 3.0);
new_value = priv->value + delta * scroll_unit;
st_adjustment_set_value (adjustment, new_value);
}

4
src/st/st-adjustment.h
View File

@ -99,6 +99,10 @@ void st_adjustment_get_values (StAdjustment *adjustment,
gdouble *step_increment,
gdouble *page_increment,
gdouble *page_size);
void st_adjustment_adjust_for_scroll_event (StAdjustment *adjustment,
gdouble delta);
G_END_DECLS
#endif /* __ST_ADJUSTMENT_H__ */

70
src/st/st-scroll-view.c
View File

@ -665,6 +665,30 @@ st_scroll_view_allocate (ClutterActor *actor,
}
static void
adjust_with_direction (StAdjustment *adj,
ClutterScrollDirection direction)
{
gdouble delta;
switch (direction)
{
case CLUTTER_SCROLL_UP:
case CLUTTER_SCROLL_LEFT:
delta = -1.0;
break;
case CLUTTER_SCROLL_RIGHT:
case CLUTTER_SCROLL_DOWN:
delta = 1.0;
break;
case CLUTTER_SCROLL_SMOOTH:
g_assert_not_reached ();
break;
}
st_adjustment_adjust_for_scroll_event (adj, delta);
}
static void
st_scroll_view_style_changed (StWidget *widget)
{
@ -687,57 +711,31 @@ st_scroll_view_scroll_event (ClutterActor *self,
ClutterScrollEvent *event)
{
StScrollViewPrivate *priv = ST_SCROLL_VIEW (self)->priv;
gdouble value, step, hvalue, vvalue, delta_x, delta_y;
/* don't handle scroll events if requested not to */
if (!priv->mouse_scroll)
return FALSE;
switch (event->direction)
{
case CLUTTER_SCROLL_SMOOTH:
clutter_event_get_scroll_delta ((ClutterEvent *)event,
&delta_x, &delta_y);
g_object_get (priv->hadjustment,
"value", &hvalue,
NULL);
g_object_get (priv->vadjustment,
"value", &vvalue,
NULL);
break;
case CLUTTER_SCROLL_UP:
case CLUTTER_SCROLL_DOWN:
g_object_get (priv->vadjustment,
"step-increment", &step,
"value", &value,
NULL);
break;
case CLUTTER_SCROLL_LEFT:
case CLUTTER_SCROLL_RIGHT:
g_object_get (priv->hadjustment,
"step-increment", &step,
"value", &value,
NULL);
break;
}
if (clutter_event_is_pointer_emulated ((ClutterEvent *) event))
return TRUE;
switch (event->direction)
{
case CLUTTER_SCROLL_SMOOTH:
st_adjustment_set_value (priv->hadjustment, hvalue + delta_x);
st_adjustment_set_value (priv->vadjustment, vvalue + delta_y);
{
gdouble delta_x, delta_y;
clutter_event_get_scroll_delta ((ClutterEvent *)event, &delta_x, &delta_y);
st_adjustment_adjust_for_scroll_event (priv->hadjustment, delta_x);
st_adjustment_adjust_for_scroll_event (priv->vadjustment, delta_y);
}
break;
case CLUTTER_SCROLL_UP:
st_adjustment_set_value (priv->vadjustment, value - step);
break;
case CLUTTER_SCROLL_DOWN:
st_adjustment_set_value (priv->vadjustment, value + step);
adjust_with_direction (priv->vadjustment, event->direction);
break;
case CLUTTER_SCROLL_LEFT:
st_adjustment_set_value (priv->hadjustment, value - step);
break;
case CLUTTER_SCROLL_RIGHT:
st_adjustment_set_value (priv->hadjustment, value + step);
adjust_with_direction (priv->hadjustment, event->direction);
break;
}