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Signals
| void | decelerate | Run First |
| void | scroll | Run First |
| void | scroll-begin | Run First |
| void | scroll-end | Run First |
Description
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 “scroll” signal (deltas in the discrete case are multiples of 1).
In the case of continuous scroll events, GtkEventControllerScroll encloses all “scroll” events between two “scroll-begin” and “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 “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 “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 3.24.
Functions
gtk_event_controller_scroll_new ()
GtkEventController * gtk_event_controller_scroll_new (GtkWidget *widget,GtkEventControllerScrollFlags flags);
Creates a new event controller that will handle scroll events
for the given widget
.
Since: 3.24
gtk_event_controller_scroll_set_flags ()
void gtk_event_controller_scroll_set_flags (GtkEventControllerScroll *controller,GtkEventControllerScrollFlags flags);
Sets the flags conditioning scroll controller behavior.
Since: 3.24
gtk_event_controller_scroll_get_flags ()
GtkEventControllerScrollFlags
gtk_event_controller_scroll_get_flags (GtkEventControllerScroll *controller);
Gets the flags conditioning the scroll controller behavior.
Since: 3.24
Types and Values
enum GtkEventControllerScrollFlags
Describes the behavior of a GtkEventControllerScroll.
Members
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Don't emit scroll. |
||
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Emit scroll with vertical deltas. |
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Emit scroll with horizontal deltas. |
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Only emit deltas that are multiples of 1. |
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Emit “decelerate” after continuous scroll finishes. |
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Emit scroll on both axes. |
Since: 3.24
Property Details
The “flags” property
“flags” GtkEventControllerScrollFlags
The flags affecting event controller behavior
Owner: GtkEventControllerScroll
Flags: Read / Write
Since: 3.24
Signal Details
The “decelerate” signal
void user_function (GtkEventControllerScroll *controller, double vel_x, double vel_y, gpointer user_data)
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.
Parameters
controller |
The object that received the signal |
|
vel_x |
X velocity |
|
vel_y |
Y velocity |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run First
The “scroll” signal
void user_function (GtkEventControllerScroll *controller, double dx, double dy, gpointer user_data)
Signals that the widget should scroll by the
amount specified by dx
and dy
.
Parameters
controller |
The object that received the signal |
|
dx |
X delta |
|
dy |
Y delta |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run First
The “scroll-begin” signal
void user_function (GtkEventControllerScroll *controller, gpointer user_data)
Signals that a new scrolling operation has begun. It will only be emitted on devices capable of it.
Parameters
controller |
The object that received the signal |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run First
The “scroll-end” signal
void user_function (GtkEventControllerScroll *controller, gpointer user_data)
Signals that a new scrolling operation has finished. It will only be emitted on devices capable of it.
Parameters
controller |
The object that received the signal |
|
user_data |
user data set when the signal handler was connected. |
Flags: Run First