*** This is an API change ***
Replaced the original drag-threshold property with two separate
horizontal (x-drag-threshold) and vertical (y-drag-threshold)
thresholds.
It is some times necessary to have different drag thresholds for the
horizontal and vertical axes. For example, when a draggable actor is
inside a horizontal scrolling area, only vertical movement must begin
dragging. That can be achieved by setting the x-drag-threshold to
G_MAXUINT while y-drag-threshold is something usual, say, 20 pixels.
This is different than drag axis, because after the threshold
has been cleared by the pointer, the draggable actor can be dragged
along both axes (if allowed by the drag-axis property).
http://bugzilla.clutter-project.org/show_bug.cgi?id=2291
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Both ::drag-begin and ::drag-end have a "button" argument - even though
we assume internally, and externally, that dragging can only be the
result of a primary button operation.
The DragAction should, by default, drag the actor to which it has been
applied, instead of delegating what to do to the developer. If custom
code need to override it, g_signal_stop_emission_by_name() can be called
to stop the default handler to ever running.
DragAction is an Action sub-class that provides dragging capabilities to
any actor. DragAction has:
• drag-begin, drag-motion and drag-end signals, relaying the event
information like coordinates, button and modifiers to user code;
• drag-threshold property, for delaying the drag start by a given
amount of pixels;
• drag-handle property, to allow using other actors as the drag
handle.
• drag-axis property, to allow constraining the dragging to a specific
axis.
An interactive test demonstrating the various features is also provided.
