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scrolledwindow: add a new edge-reached signal

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This will be used to just detect when an edge of the scrollable area is
reached - as opposed to the edge-overshot signal that is emitted when
the user scrolls past the edge.

https://bugzilla.gnome.org/show_bug.cgi?id=742848
This commit is contained in:
Cosimo Cecchi 2015-01-25 11:53:49 +00:00
parent 48a41b0119
commit 404e2753c4
2 changed files with 74 additions and 3 deletions
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68
gtk/gtkscrolledwindow.c
View File

@ -260,6 +260,7 @@ enum
SCROLL_CHILD,
MOVE_FOCUS_OUT,
EDGE_OVERSHOT,
EDGE_REACHED,
LAST_SIGNAL
};
@ -656,9 +657,8 @@ gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
* makes the scrolledwindow firmly surpass (ie. with some edge resistance)
* the lower or upper limits defined by the adjustment in that orientation.
*
* If a similar behavior without edge resistance is desired, one alternative
* may be to check on #GtkAdjustment::value-changed that the value equals
* either #GtkAdjustment:lower or #GtkAdjustment:upper - #GtkAdjustment:page-size.
* A similar behavior without edge resistance is provided by the
* #GtkScrolledWindow::edge-reached signal.
*
* Note: The @pos argument is LTR/RTL aware, so callers should be aware too
* if intending to provide behavior on horizontal edges.
@ -673,6 +673,31 @@ gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
g_cclosure_marshal_generic,
G_TYPE_NONE, 1, GTK_TYPE_POSITION_TYPE);
/**
* GtkScrolledWindow::edge-reached:
* @scrolled_window: a #GtkScrolledWindow
* @pos: edge side that was reached
*
* The ::edge-reached signal is emitted whenever user-initiated scrolling
* makes the scrolledwindow exactly reaches the lower or upper limits
* defined by the adjustment in that orientation.
*
* A similar behavior with edge resistance is provided by the
* #GtkScrolledWindow::edge-overshot signal.
*
* Note: The @pos argument is LTR/RTL aware, so callers should be aware too
* if intending to provide behavior on horizontal edges.
*
* Since: 3.16
*/
signals[EDGE_REACHED] =
g_signal_new (I_("edge-reached"),
G_TYPE_FROM_CLASS (gobject_class),
G_SIGNAL_RUN_LAST, 0,
NULL, NULL,
g_cclosure_marshal_generic,
G_TYPE_NONE, 1, GTK_TYPE_POSITION_TYPE);
binding_set = gtk_binding_set_by_class (class);
add_scroll_binding (binding_set, GDK_KEY_Left, GDK_CONTROL_MASK, GTK_SCROLL_STEP_BACKWARD, TRUE);
@ -3215,6 +3240,41 @@ gtk_scrolled_window_adjustment_changed (GtkAdjustment *adjustment,
}
}
static void
maybe_emit_edge_reached (GtkScrolledWindow *scrolled_window,
GtkAdjustment *adjustment)
{
GtkScrolledWindowPrivate *priv = scrolled_window->priv;
gdouble value, lower, upper, page_size;
GtkPositionType edge_pos;
gboolean vertical;
if (adjustment == gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)))
vertical = FALSE;
else if (adjustment == gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)))
vertical = TRUE;
else
return;
value = gtk_adjustment_get_value (adjustment);
lower = gtk_adjustment_get_lower (adjustment);
upper = gtk_adjustment_get_upper (adjustment);
page_size = gtk_adjustment_get_page_size (adjustment);
if (value == lower)
edge_pos = vertical ? GTK_POS_TOP: GTK_POS_LEFT;
else if (value == upper - page_size)
edge_pos = vertical ? GTK_POS_BOTTOM : GTK_POS_RIGHT;
else
return;
if (!vertical &&
gtk_widget_get_direction (GTK_WIDGET (scrolled_window)) == GTK_TEXT_DIR_RTL)
edge_pos = (edge_pos == GTK_POS_LEFT) ? GTK_POS_RIGHT : GTK_POS_LEFT;
g_signal_emit (scrolled_window, signals[EDGE_REACHED], 0, edge_pos);
}
static void
gtk_scrolled_window_adjustment_value_changed (GtkAdjustment *adjustment,
gpointer user_data)
@ -3222,6 +3282,8 @@ gtk_scrolled_window_adjustment_value_changed (GtkAdjustment *adjustment,
GtkScrolledWindow *scrolled_window = user_data;
GtkScrolledWindowPrivate *priv = scrolled_window->priv;
maybe_emit_edge_reached (scrolled_window, adjustment);
/* Allow overshooting for kinetic scrolling operations */
if (priv->drag_device || priv->deceleration_id)
return;

9
tests/testscrolledge.c
View File

@ -80,6 +80,14 @@ edge_overshot (GtkScrolledWindow *sw,
}
}
static void
edge_reached (GtkScrolledWindow *sw,
GtkPositionType pos,
GtkListBox *list)
{
g_print ("Reached the edge at pos %d!\n", pos);
}
int
main (int argc, char *argv[])
{
@ -120,6 +128,7 @@ main (int argc, char *argv[])
populate_list (GTK_LIST_BOX (list));
g_signal_connect (sw, "edge-overshot", G_CALLBACK (edge_overshot), list);
g_signal_connect (sw, "edge-reached", G_CALLBACK (edge_reached), list);
gtk_widget_show_all (win);