private void _DrawingBoard_PanelDragging(object sender, BoardDraggingEventArgs e)
{
if (_DrawingBoard.Width <= Width && _DrawingBoard.Height <= Height)
{
return;
}
//根据拖动的起点和当前点之间的距离，触发滚动条的Value发生变化，再间接触发画板的移动
Point current = PointToClient(_DrawingBoard.PointToScreen(e.CurrentPoint));
Point start = PointToClient(_DrawingBoard.PointToScreen(e.StartPoint));
int x = (current.X - start.X) / 3;
int y = (current.Y - start.Y) / 3;
int offsetX = _HScrollBar.Value - x;
if (offsetX > _HScrollBar.Minimum && offsetX < _HScrollBar.Maximum)
{
_HScrollBar.Value = offsetX;
}
int offsetY = _VScrollBar.Value - y;
if (offsetY > _VScrollBar.Minimum && offsetY < _VScrollBar.Maximum)
{
_VScrollBar.Value = _VScrollBar.Value - y;
}
//TODO:左与上的边距有了，为什么下与右的边距没有呢？
}
private void OnBoardDragging(BoardDraggingEventArgs e)
{
EventHandler <BoardDraggingEventArgs> handler = BoardDragging;
if (handler != null)
{
handler(this, e);
}
}
