_DragAvatar <T> _startDrag(Offset position)
{
if (this.widget.maxSimultaneousDrags != null &&
this._activeCount >= this.widget.maxSimultaneousDrags)
{
return(null);
}
var dragStartPoint = Offset.zero;
switch (this.widget.dragAnchor)
{
case DragAnchor.child:
RenderBox renderObject = this.context.findRenderObject() as RenderBox;
dragStartPoint = renderObject.globalToLocal(position);
break;
case DragAnchor.pointer:
dragStartPoint = Offset.zero;
break;
}
this.setState(() => { this._activeCount += 1; });
_DragAvatar <T> avatar = new _DragAvatar <T>(
overlayState: Overlay.of(this.context, debugRequiredFor: this.widget),
data: this.widget.data,
axis: this.widget.axis,
initialPosition: position,
dragStartPoint: dragStartPoint,
feedback: this.widget.feedback,
feedbackOffset: this.widget.feedbackOffset,
onDragEnd: (Velocity velocity, Offset offset, bool wasAccepted) => {
if (this.mounted)
{
this.setState(() => { this._activeCount -= 1; });
}
else
{
this._activeCount -= 1;
this._disposeRecognizerIfInactive();
}
if (this.mounted && this.widget.onDragEnd != null)
{
this.widget.onDragEnd(new DraggableDetails(
wasAccepted: wasAccepted,
velocity: velocity,
offset: offset
));
}
if (wasAccepted && this.widget.onDragCompleted != null)
{
this.widget.onDragCompleted();
}
if (!wasAccepted && this.widget.onDraggableCanceled != null)
{
this.widget.onDraggableCanceled(velocity, offset);
}
}
);
if (this.widget.onDragStarted != null)
{
this.widget.onDragStarted();
}
return(avatar);
}