/// <summary>
/// Updates position until stopDragging completes.
/// </summary>
public static async Task <IBehavior> DragRelative(this IBehavior self,
V2d initialPosition, IEvent <V2d> moves, IAwaitable stopDragging, CancellationToken ct
)
{
var obj = self as IBehaviorTransform2d;
if (obj == null)
{
throw new InvalidOperationException("DragRelative requires IBehaviorTransform2d.");
}
var lastPos = initialPosition;
await stopDragging.RepeatUntilCompleted(
async delegate
{
var p = await moves.Next.WithCancellation(ct);
obj.Transform(M33d.Translation(p - lastPos));
lastPos = p;
});
return(self);
}
/// <summary>
/// Updates position until stopDragging completes.
/// </summary>
public static async Task <IBehavior> DragAbsolute(this IBehavior self,
IEvent <V2d> positions, IAwaitable stopDragging, CancellationToken ct
)
{
var obj = self as IBehaviorPosition2d;
if (obj == null)
{
throw new InvalidOperationException("DragAbsolute requires IBehaviorPosition2d.");
}
await stopDragging.RepeatUntilCompleted(async delegate
{
var p = await positions.Next.WithCancellation(ct);
if (stopDragging.IsCompleted)
{
return;
}
obj.Position = p;
});
return(self);
}
