#include "stage/interact/drag-relocate-controller.hpp"

Description

Gesture controller for dragging objects within the Timeline display.

The gesture to drag an entity is triggered by observing mouse movements while a mouse key and possibly some modifier key is pressed. To recognise this condition, every possible subject for a drag gesture will be wired through the linkTrigger call into this controller. When #detectActivation is fulfilled for one specific subject, the corresponding context data will be tracked as state of the ongoing gesture in formation, maintained within the member fields of this controller.

Todo:: write type comment...

Remarks

tracking of signal connections is not relevant here, since this controller is managed by the UI backbone and thus ensured to outlive any event processing.
this concrete controller handles all drag-relocate gestures for all widgets
the actual Subject (widget) and command are bound into the signal wiring
whenever a new gesture possibly starts, we pick up these arguments and store them into the current gesture state within this object's fields.

Todo:: WIP-WIP as of /3/2021 ///////////////////////////////////TODO do we need a translation unit interaction-state.cpp (otherwise delete it!)

Definition at line 96 of file drag-relocate-controller.hpp.

Public Member Functions
	DragRelocateController ()

Private Types
using	Observer = lib::InPlaceBuffer< GestureObserver, OBSERVER_BUFF_SIZ, InactiveObserver >

Private Member Functions
void	linkTrigger (Subject &subject, Symbol cmdID) override
	Hook up a trigger signal to initiate a specific interaction gesture.

bool	watchButton (GdkEventButton *button_event) noexcept

bool	maybeActivate (Symbol cmdID, Subject &subject, GdkEventMotion *motion_event)
	Gesture detection state logic.

bool	isActive ()

bool	isAnchored ()

void	anchor (Symbol cmdID, Subject &subject, GdkEventMotion *motion_event)

void	probeActivation (GdkEventMotion *motion_event)

void	initGestureTracking (Symbol cmdID, Subject &subject)

void	doTrackGesture (GdkEventMotion *motion_event)

void	doCompleteGesture ()

void	resetState ()

Private Attributes
bool	buttonPressed_ = false

Subject *	subject_ = nullptr

bool	isInFormation_ = false

gdouble	anchorX_ = 0.0

gdouble	anchorY_ = 0.0

Observer	observer_

Additional Inherited Members
Protected Member Functions inherited from InteractionState
virtual	~InteractionState ()
	this is an interface

Constructor & Destructor Documentation

◆ DragRelocateController()

DragRelocateController ( )

inline

Definition at line 242 of file drag-relocate-controller.hpp.

Member Typedef Documentation

◆ Observer

using Observer = lib::InPlaceBuffer<GestureObserver, OBSERVER_BUFF_SIZ, InactiveObserver>

private

Definition at line 105 of file drag-relocate-controller.hpp.

Member Function Documentation

◆ linkTrigger()

void linkTrigger	(	Subject &	,
		Symbol	cmdID
	)

inlineoverrideprivatevirtual

Hook up a trigger signal to initiate a specific interaction gesture.

Within the concrete controller implementation for each gesture, the Subject interface shall be used to access an actual widget and to wire this widget's signals to a private implementation function within the concrete gesture controller. The purpose is then to observe this widget and to activate recognition of the gesture when applicable.

Parameters

Subject	the subject of the interaction gesture; typically implemented by a controller or widget responsible for the UI entity involved.
cmdID	the actual command to be issued on completion of the interaction

Remarks: typically this contextual information is bound into the signal wiring, meaning that the actual interaction context will be established "late", i.e. only when an actual gesture is about to commence

Implements InteractionState.

Definition at line 110 of file drag-relocate-controller.hpp.

References Subject::exposeWidget(), DragRelocateController::maybeActivate(), ON_EXCEPTION_RETURN, and DragRelocateController::watchButton().

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