gnome-shell/js/ui/dnd.js

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/* -*- mode: js2; js2-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil -*- */
const Clutter = imports.gi.Clutter;
const Gtk = imports.gi.Gtk;
const Lang = imports.lang;
const Signals = imports.signals;
const Tweener = imports.ui.tweener;
const SNAP_BACK_ANIMATION_TIME = 0.25;
function _Draggable(actor) {
this._init(actor);
}
_Draggable.prototype = {
_init : function(actor) {
this.actor = actor;
this.actor.connect('button-press-event',
Lang.bind(this, this._onButtonPress));
},
_onButtonPress : function (actor, event) {
// FIXME: we should make sure it's button 1, but we can't currently
// check that from JavaScript
if (Tweener.getTweenCount(actor))
return false;
this._grabActor(actor);
let [stageX, stageY] = event.get_coords();
this._dragStartX = stageX;
this._dragStartY = stageY;
return false;
},
_grabActor : function (actor) {
Clutter.grab_pointer(actor);
// We intercept motion and button-release events so that when
// you release after dragging, the app doesn't see that and
// think you just clicked. We connect to 'event' rather than
// 'captured-event' because the capturing phase doesn't happen
// when you've grabbed the pointer.
this._onEventId = actor.connect('event',
Lang.bind(this, this._onEvent));
},
_ungrabActor : function (actor) {
Clutter.ungrab_pointer();
actor.disconnect(this._onEventId);
},
_onEvent : function (actor, event) {
if (this._dragActor) {
if (actor != this._dragActor )
return false;
} else if (actor != this.actor)
return false;
if (event.type() == Clutter.EventType.BUTTON_RELEASE)
return this._onButtonRelease(actor, event);
else if (event.type() == Clutter.EventType.MOTION)
return this._onMotion(actor, event);
else
return false;
},
_onMotion : function (actor, event) {
let [stageX, stageY] = event.get_coords();
// If we haven't begun a drag, see if the user has moved the
// mouse enough to trigger a drag
let threshold = Gtk.Settings.get_default().gtk_dnd_drag_threshold;
if (!this._dragActor &&
(Math.abs(stageX - this._dragStartX) > threshold ||
Math.abs(stageY - this._dragStartY) > threshold)) {
this.emit('drag-begin', event.get_time());
if (this.actor._delegate && this.actor._delegate.getDragActor) {
this._dragActor = this.actor._delegate.getDragActor(this._dragStartX, this._dragStartY);
// Drag actor does not always have to be the same as actor. For example drag actor
// can be an image that's part of the actor. So to perform "snap back" correctly we need
// to know what was the drag actor source.
if (this.actor._delegate.getDragActorSource)
this._dragActorSource = this.actor._delegate.getDragActorSource();
else
this._dragActorSource = this.actor;
this._dragOrigParent = undefined;
this._ungrabActor(actor);
this._grabActor(this._dragActor);
this._dragOffsetX = this._dragActor.x - this._dragStartX;
this._dragOffsetY = this._dragActor.y - this._dragStartY;
} else {
this._dragActor = actor;
this._dragActorSource = undefined;
this._dragOrigParent = actor.get_parent();
this._dragOrigX = this._dragActor.x;
this._dragOrigY = this._dragActor.y;
this._dragOrigScale = this._dragActor.scale_x;
let [actorStageX, actorStageY] = actor.get_transformed_position();
this._dragOffsetX = actorStageX - this._dragStartX;
this._dragOffsetY = actorStageY - this._dragStartY;
// Set the actor's scale such that it will keep the same
// transformed size when it's reparented to the stage
let [scaledWidth, scaledHeight] = actor.get_transformed_size();
actor.set_scale(scaledWidth / actor.width,
scaledHeight / actor.height);
}
this._dragActor.reparent(actor.get_stage());
this._dragActor.raise_top();
}
// If we are dragging, update the position
if (this._dragActor) {
this._dragActor.set_position(stageX + this._dragOffsetX,
stageY + this._dragOffsetY);
// Because we want to find out what other actor is located at the current position of this._dragActor,
// we have to temporarily hide this._dragActor.
this._dragActor.hide();
let target = actor.get_stage().get_actor_at_pos(stageX + this._dragOffsetX, stageY + this._dragOffsetY);
this._dragActor.show();
while (target) {
if (target._delegate && target._delegate.handleDragOver) {
let [targX, targY] = target.get_transformed_position();
// We currently loop through all parents on drag-over even if one of the children has handled it.
// We can check the return value of the function and break the loop if it's true if we don't want
// to continue checking the parents.
target._delegate.handleDragOver(this.actor._delegate, actor,
(stageX + this._dragOffsetX + this._xOffset - targX) / target.scale_x,
(stageY + this._dragOffsetY + this._yOffset - targY) / target.scale_y,
event.get_time());
}
target = target.get_parent();
}
}
return true;
},
_onButtonRelease : function (actor, event) {
this._ungrabActor(actor);
let dragging = (actor == this._dragActor);
this._dragActor = undefined;
if (!dragging)
return false;
this.emit('drag-end', event.get_time());
// Find a drop target
actor.hide();
let [dropX, dropY] = event.get_coords();
let target = actor.get_stage().get_actor_at_pos(dropX, dropY);
actor.show();
while (target) {
if (target._delegate && target._delegate.acceptDrop) {
let [targX, targY] = target.get_transformed_position();
if (target._delegate.acceptDrop(this.actor._delegate, actor,
(dropX + this._xOffset - targX) / target.scale_x,
(dropY + this._yOffset - targY) / target.scale_y,
event.get_time())) {
// If it accepted the drop without taking the actor,
// destroy it.
if (actor.get_parent() == actor.get_stage())
actor.destroy();
return true;
}
}
target = target.get_parent();
}
// Snap back to the actor source if the source is still around, snap back
// to the original location if the actor itself was being dragged or the
// source is no longer around.
let snapBackX = this._dragStartX + this._dragOffsetX;
let snapBackY = this._dragStartY + this._dragOffsetY;
if (this._dragActorSource && this._dragActorSource.visible) {
[snapBackX, snapBackY] = this._dragActorSource.get_transformed_position();
}
// No target, so snap back
Tweener.addTween(actor,
{ x: snapBackX,
y: snapBackY,
time: SNAP_BACK_ANIMATION_TIME,
transition: "easeOutQuad",
onComplete: this._onSnapBackComplete,
onCompleteScope: this,
onCompleteParams: [actor]
});
return true;
},
_onSnapBackComplete : function (dragActor) {
if (this._dragOrigParent) {
dragActor.reparent(this._dragOrigParent);
dragActor.set_scale(this._dragOrigScale, this._dragOrigScale);
dragActor.set_position(this._dragOrigX, this._dragOrigY);
} else
dragActor.destroy();
}
};
Signals.addSignalMethods(_Draggable.prototype);
function makeDraggable(actor) {
return new _Draggable(actor);
}