gtk2/gtk/gtkeventcontrollerscroll.c
2017-12-02 00:29:37 +01:00

517 lines
15 KiB
C

/* GTK - The GIMP Toolkit
* Copyright (C) 2017, Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Author(s): Carlos Garnacho <carlosg@gnome.org>
*/
/**
* SECTION:gtkeventcontrollerscroll
* @Short_description: Event controller for scroll events
* @Title: GtkEventControllerScroll
* @See_also: #GtkEventController
*
* #GtkEventControllerScroll is an event controller meant to handle
* scroll events from mice and touchpads. It is capable of handling
* both discrete and continuous scroll events, abstracting them both
* on the #GtkEventControllerScroll::scroll signal (deltas in the
* discrete case are multiples of 1).
*
* In the case of continuous scroll events, #GtkEventControllerScroll
* encloses all #GtkEventControllerScroll::scroll events between two
* #GtkEventControllerScroll::scroll-begin and #GtkEventControllerScroll::scroll-end
* signals.
*
* The behavior of the event controller can be modified by the
* flags given at creation time, or modified at a later point through
* gtk_event_controller_scroll_set_flags() (e.g. because the scrolling
* conditions of the widget changed).
*
* The controller can be set up to emit motion for either/both vertical
* and horizontal scroll events through #GTK_EVENT_CONTROLLER_SCROLL_VERTICAL,
* #GTK_EVENT_CONTROLLER_SCROLL_HORIZONTAL and #GTK_EVENT_CONTROLLER_SCROLL_BOTH.
* If any axis is disabled, the respective #GtkEventControllerScroll::scroll
* delta will be 0. Vertical scroll events will be translated to horizontal
* motion for the devices incapable of horizontal scrolling.
*
* The event controller can also be forced to emit discrete events on all devices
* through #GTK_EVENT_CONTROLLER_SCROLL_DISCRETE. This can be used to implement
* discrete actions triggered through scroll events (e.g. switching across
* combobox options).
*
* The #GTK_EVENT_CONTROLLER_SCROLL_KINETIC flag toggles the emission of the
* #GtkEventControllerScroll::decelerate signal, emitted at the end of scrolling
* with two X/Y velocity arguments that are consistent with the motion that
* was received.
*
* This object was added in 3.93.
**/
#include "config.h"
#include "gtkintl.h"
#include "gtkwidget.h"
#include "gtkeventcontrollerprivate.h"
#include "gtkeventcontrollerscroll.h"
#include "gtktypebuiltins.h"
#include "gtkmarshalers.h"
#define SCROLL_CAPTURE_THRESHOLD_MS 150
typedef struct
{
gdouble dx;
gdouble dy;
guint32 evtime;
} ScrollHistoryElem;
struct _GtkEventControllerScroll
{
GtkEventController parent_instance;
GtkEventControllerScrollFlags flags;
GArray *scroll_history;
/* For discrete event coalescing */
gdouble cur_dx;
gdouble cur_dy;
guint active : 1;
};
struct _GtkEventControllerScrollClass
{
GtkEventControllerClass parent_class;
};
enum {
SCROLL_BEGIN,
SCROLL,
SCROLL_END,
DECELERATE,
N_SIGNALS
};
enum {
PROP_0,
PROP_FLAGS,
N_PROPS
};
static GParamSpec *pspecs[N_PROPS] = { NULL };
static guint signals[N_SIGNALS] = { 0 };
G_DEFINE_TYPE (GtkEventControllerScroll, gtk_event_controller_scroll,
GTK_TYPE_EVENT_CONTROLLER)
static void
scroll_history_push (GtkEventControllerScroll *scroll,
gdouble delta_x,
gdouble delta_y,
guint32 evtime)
{
ScrollHistoryElem new_item;
guint i;
for (i = 0; i < scroll->scroll_history->len; i++)
{
ScrollHistoryElem *elem;
elem = &g_array_index (scroll->scroll_history, ScrollHistoryElem, i);
if (elem->evtime >= evtime - SCROLL_CAPTURE_THRESHOLD_MS)
break;
}
if (i > 0)
g_array_remove_range (scroll->scroll_history, 0, i);
new_item.dx = delta_x;
new_item.dy = delta_y;
new_item.evtime = evtime;
g_array_append_val (scroll->scroll_history, new_item);
}
static void
scroll_history_reset (GtkEventControllerScroll *scroll)
{
if (scroll->scroll_history->len == 0)
return;
g_array_remove_range (scroll->scroll_history, 0,
scroll->scroll_history->len);
}
static void
scroll_history_finish (GtkEventControllerScroll *scroll,
gdouble *velocity_x,
gdouble *velocity_y)
{
gdouble accum_dx = 0, accum_dy = 0;
guint32 first = 0, last = 0;
guint i;
*velocity_x = 0;
*velocity_y = 0;
if (scroll->scroll_history->len == 0)
return;
for (i = 0; i < scroll->scroll_history->len; i++)
{
ScrollHistoryElem *elem;
elem = &g_array_index (scroll->scroll_history, ScrollHistoryElem, i);
accum_dx += elem->dx;
accum_dy += elem->dy;
last = elem->evtime;
if (i == 0)
first = elem->evtime;
}
if (last != first)
{
*velocity_x = (accum_dx * 1000) / (last - first);
*velocity_y = (accum_dy * 1000) / (last - first);
}
scroll_history_reset (scroll);
}
static void
gtk_event_controller_scroll_finalize (GObject *object)
{
GtkEventControllerScroll *scroll = GTK_EVENT_CONTROLLER_SCROLL (object);
g_array_unref (scroll->scroll_history);
G_OBJECT_CLASS (gtk_event_controller_scroll_parent_class)->finalize (object);
}
static void
gtk_event_controller_scroll_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GtkEventControllerScroll *scroll = GTK_EVENT_CONTROLLER_SCROLL (object);
switch (prop_id)
{
case PROP_FLAGS:
scroll->flags = g_value_get_flags (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gtk_event_controller_scroll_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GtkEventControllerScroll *scroll = GTK_EVENT_CONTROLLER_SCROLL (object);
switch (prop_id)
{
case PROP_FLAGS:
g_value_set_flags (value, scroll->flags);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static gboolean
gtk_event_controller_scroll_handle_event (GtkEventController *controller,
const GdkEvent *event)
{
GtkEventControllerScroll *scroll = GTK_EVENT_CONTROLLER_SCROLL (controller);
GdkScrollDirection direction = GDK_SCROLL_SMOOTH;
gdouble dx = 0, dy = 0;
if (gdk_event_get_event_type (event) != GDK_SCROLL)
return FALSE;
if ((scroll->flags & (GTK_EVENT_CONTROLLER_SCROLL_VERTICAL |
GTK_EVENT_CONTROLLER_SCROLL_HORIZONTAL)) == 0)
return FALSE;
/* FIXME: Handle device changes */
if (gdk_event_get_scroll_deltas (event, &dx, &dy))
{
GdkDevice *device = gdk_event_get_source_device (event);
GdkInputSource input_source = gdk_device_get_source (device);
if (!scroll->active &&
(input_source == GDK_SOURCE_TRACKPOINT ||
input_source == GDK_SOURCE_TOUCHPAD))
{
g_signal_emit (controller, signals[SCROLL_BEGIN], 0);
scroll_history_reset (scroll);
scroll->active = TRUE;
}
if ((scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_VERTICAL) == 0)
dy = 0;
if ((scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_HORIZONTAL) == 0)
dx = 0;
if (scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_DISCRETE)
{
gint steps;
scroll->cur_dx += dx;
scroll->cur_dy += dy;
dx = dy = 0;
if (ABS (scroll->cur_dx) >= 1)
{
steps = trunc (scroll->cur_dx);
scroll->cur_dx -= steps;
dx = steps;
}
if (ABS (scroll->cur_dy) >= 1)
{
steps = trunc (scroll->cur_dy);
scroll->cur_dy -= steps;
dy = steps;
}
}
}
else if (gdk_event_get_scroll_direction (event, &direction))
{
switch (direction)
{
case GDK_SCROLL_UP:
dy -= 1;
break;
case GDK_SCROLL_DOWN:
dy += 1;
break;
case GDK_SCROLL_LEFT:
dx -= 1;
break;
case GDK_SCROLL_RIGHT:
dx += 1;
break;
case GDK_SCROLL_SMOOTH:
default:
g_assert_not_reached ();
break;
}
if ((scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_VERTICAL) == 0)
dy = 0;
if ((scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_HORIZONTAL) == 0)
dx = 0;
}
if (dx != 0 || dy != 0)
{
g_signal_emit (controller, signals[SCROLL], 0, dx, dy);
if (scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_KINETIC)
scroll_history_push (scroll, dx, dy, gdk_event_get_time (event));
}
if (scroll->active && gdk_event_is_scroll_stop_event (event))
{
g_signal_emit (controller, signals[SCROLL_END], 0);
scroll->active = FALSE;
if (scroll->flags & GTK_EVENT_CONTROLLER_SCROLL_KINETIC)
{
gdouble vel_x, vel_y;
scroll_history_finish (scroll, &vel_x, &vel_y);
g_signal_emit (controller, signals[DECELERATE], 0, vel_x, vel_y);
}
}
return TRUE;
}
static void
gtk_event_controller_scroll_class_init (GtkEventControllerScrollClass *klass)
{
GtkEventControllerClass *controller_class = GTK_EVENT_CONTROLLER_CLASS (klass);
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->finalize = gtk_event_controller_scroll_finalize;
object_class->set_property = gtk_event_controller_scroll_set_property;
object_class->get_property = gtk_event_controller_scroll_get_property;
controller_class->handle_event = gtk_event_controller_scroll_handle_event;
/**
* GtkEventControllerScroll:flags:
*
* The flags affecting event controller behavior
*
* Since: 3.93
**/
pspecs[PROP_FLAGS] =
g_param_spec_flags ("flags",
P_("Flags"),
P_("Flags"),
GTK_TYPE_EVENT_CONTROLLER_SCROLL_FLAGS,
GTK_EVENT_CONTROLLER_SCROLL_NONE,
G_PARAM_READWRITE |
G_PARAM_CONSTRUCT_ONLY);
/**
* GtkEventControllerScroll::scroll-begin:
* @controller: The object that received the signal
*
* Signals that a new scrolling operation has begun. It will
* only be emitted on devices capable of it.
**/
signals[SCROLL_BEGIN] =
g_signal_new (I_("scroll-begin"),
GTK_TYPE_EVENT_CONTROLLER_SCROLL,
G_SIGNAL_RUN_FIRST,
0, NULL, NULL,
g_cclosure_marshal_VOID__VOID,
G_TYPE_NONE, 0);
/**
* GtkEventControllerScroll::scroll:
* @controller: The object that received the signal
* @dx: X delta
* @dy: Y delta
*
* Signals that the widget should scroll by the
* amount specified by @dx and @dy.
**/
signals[SCROLL] =
g_signal_new (I_("scroll"),
GTK_TYPE_EVENT_CONTROLLER_SCROLL,
G_SIGNAL_RUN_FIRST,
0, NULL, NULL,
_gtk_marshal_VOID__DOUBLE_DOUBLE,
G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
/**
* GtkEventControllerScroll::scroll-end:
* @controller: The object that received the signal
*
* Signals that a new scrolling operation has finished. It will
* only be emitted on devices capable of it.
**/
signals[SCROLL_END] =
g_signal_new (I_("scroll-end"),
GTK_TYPE_EVENT_CONTROLLER_SCROLL,
G_SIGNAL_RUN_FIRST,
0, NULL, NULL,
g_cclosure_marshal_VOID__VOID,
G_TYPE_NONE, 0);
/**
* GtkEventControllerScroll::decelerate:
* @controller: The object that received the signal
* @vel_x: X velocity
* @vel_y: Y velocity
*
* Emitted after scroll is finished if the #GTK_EVENT_CONTROLLER_SCROLL_KINETIC
* flag is set. @vel_x and @vel_y express the initial velocity that was
* imprinted by the scroll events. @vel_x and @vel_y are expressed in
* pixels/ms.
**/
signals[DECELERATE] =
g_signal_new (I_("decelerate"),
GTK_TYPE_EVENT_CONTROLLER_SCROLL,
G_SIGNAL_RUN_FIRST,
0, NULL, NULL,
_gtk_marshal_VOID__DOUBLE_DOUBLE,
G_TYPE_NONE, 2, G_TYPE_DOUBLE, G_TYPE_DOUBLE);
g_object_class_install_properties (object_class, N_PROPS, pspecs);
}
static void
gtk_event_controller_scroll_init (GtkEventControllerScroll *scroll)
{
scroll->scroll_history = g_array_new (FALSE, FALSE,
sizeof (ScrollHistoryElem));
}
/**
* gtk_event_controller_scroll_new:
* @widget: a #GtkWidget
* @flags: behavior flags
*
* Creates a new event controller that will handle scroll events
* for the given @widget.
*
* Returns: a new #GtkEventControllerScroll
*
* Since: 3.93
**/
GtkEventController *
gtk_event_controller_scroll_new (GtkWidget *widget,
GtkEventControllerScrollFlags flags)
{
g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
return g_object_new (GTK_TYPE_EVENT_CONTROLLER_SCROLL,
"widget", widget,
"flags", flags,
NULL);
}
/**
* gtk_event_controller_scroll_set_flags:
* @scroll: a #GtkEventControllerScroll
* @flags: behavior flags
*
* Sets the flags conditioning scroll controller behavior.
*
* Since: 3.93
**/
void
gtk_event_controller_scroll_set_flags (GtkEventControllerScroll *scroll,
GtkEventControllerScrollFlags flags)
{
g_return_if_fail (GTK_IS_EVENT_CONTROLLER_SCROLL (scroll));
if (scroll->flags != flags)
{
scroll->flags = flags;
g_object_notify (G_OBJECT (scroll), "flags");
}
}
/**
* gtk_event_controller_scroll_get_flags:
* @scroll: a #GtkEventControllerScroll
*
* Gets the flags conditioning the scroll controller behavior.
*
* Returns: the controller flags.
*
* Since: 3.93
**/
GtkEventControllerScrollFlags
gtk_event_controller_scroll_get_flags (GtkEventControllerScroll *scroll)
{
g_return_val_if_fail (GTK_IS_EVENT_CONTROLLER_SCROLL (scroll),
GTK_EVENT_CONTROLLER_SCROLL_NONE);
return scroll->flags;
}