Code

	//extract view state
	RectangleF viewBounds = diagramView.Bounds;
	float viewWidth = viewBounds.Width;
	float viewHeight = viewBounds.Height;
	float viewX = viewBounds.X;
	float viewY = viewBounds.Y;

	//extract document state
	RectangleF docBounds = diagram.Bounds;
	float docWidth = docBounds.Width;
	float docHeight = docBounds.Height;

	//scrolling necessary
	if (docWidth >= viewWidth &&
	    docHeight >= viewHeight) return false;

	//prepare scrolling
	float scrollX = -1;
	float scrollY = -1;

	//scrolling X necessary
	if (viewWidth < docWidth) {
	  float maxScrollX = docWidth - viewWidth;
	  float centerX = rectangle.X + (rectangle.Width / 2);
	  scrollX = centerX - (viewWidth / 2);
	  if (scrollX < 0) scrollX = 0;
	  if (scrollX > maxScrollX) scrollX = maxScrollX;
	} else {
	  //take current value
	  scrollX = viewX;
	}

	//scrolling Y necessary
	if (viewHeight < docHeight) {
	  float maxScrollY = docHeight - viewHeight;
	  float centerY = rectangle.Y + (rectangle.Height / 2);
	  scrollY = centerY - (viewHeight / 2);
	  if (scrollY < 0) scrollY = 0;
	  if (scrollY > maxScrollY) scrollY = maxScrollY;
	} else {
	  //take current value
	  scrollY = viewY;
	}

	//do scrolling
	diagramView.ScrollTo(scrollX, scrollY);