FixedSlidingHingeJoint CreateBorderJoint(Orientation orientation)
{
FixedSlidingHingeJoint joint = new FixedSlidingHingeJoint(Body, new Vector2D(0, 0), new Lifespan(), orientation);
joint.Softness = borderSoftness;
engine.AddJoint(joint);
return joint;
}
void PhysicsTimerCallback(double dt, double trueDt)
{
engine.Update(dt, trueDt);
if (Body != null)
{
Vector2D position = -Body.State.Position.Linear;
Dispatcher.Invoke(DispatcherPriority.Normal, (Action)(() =>
{
ScrollToHorizontalOffset(position.X);
ScrollToVerticalOffset(position.Y);
}));
if (position.X < ContentDecorator.BORDER)
{
if (horizontalJoint == null)
{
Body.State.Position.Linear = new Vector2D(-ContentDecorator.BORDER, -position.Y);
horizontalJoint = CreateBorderJoint(Orientation.Horizontal);
}
}
else if (position.X > ScrollableWidth - ContentDecorator.BORDER)
{
if (horizontalJoint == null)
{
Body.State.Position.Linear = new Vector2D(-ScrollableWidth + ContentDecorator.BORDER, -position.Y);
horizontalJoint = CreateBorderJoint(Orientation.Horizontal);
}
}
else if (firstContactId.HasValue && horizontalJoint != null)
{
horizontalJoint.Lifetime.IsExpired = true;
horizontalJoint = null;
}
if (position.Y < ContentDecorator.BORDER)
{
if (verticalJoint == null)
{
Body.State.Position.Linear = new Vector2D(-position.X, -ContentDecorator.BORDER);
verticalJoint = CreateBorderJoint(Orientation.Vertical);
}
}
else if (position.Y > ScrollableHeight - ContentDecorator.BORDER)
{
if (verticalJoint == null)
{
Body.State.Position.Linear = new Vector2D(-position.X, -ScrollableHeight + ContentDecorator.BORDER);
verticalJoint = CreateBorderJoint(Orientation.Vertical);
}
}
else if (firstContactId.HasValue && verticalJoint != null)
{
verticalJoint.Lifetime.IsExpired = true;
verticalJoint = null;
}
}
}