众所周知，我们可以将鼠标放在windows窗体的边框上，按住鼠标左键改变窗体大小。那么，在silverlight上如何实现呢？
1. 需要将改控件放置在canvas上。
2. 判断鼠标位置，然后将Arrow鼠标形状改变为相应的Resize形状（本实例默认当鼠标处于边框内5px时，可resize）：
//the left top corner if (location.Y <5 && location.X <5) { this.Cursor = Cursors.SizeNWSE; currentEdgeCorner = EdgeCorner.LeftTopCorner; } //the right top corner else if (location.Y <5 && this.Width - location.X <5) { this.Cursor = Cursors.SizeNESW; currentEdgeCorner = EdgeCorner.RightTopCorner; } //the right bottom corner else if (this.Width - location.X <5 && this.Height - location.Y <5) { this.Cursor = Cursors.SizeNWSE; currentEdgeCorner = EdgeCorner.RightBottomCorner; } // the left bottom corner else if (location.X <5 && this.Height - location.Y <5) { this.Cursor = Cursors.SizeNESW; currentEdgeCorner = EdgeCorner.LeftBottomCorner; } //the left edge else if (location.X <5) { this.Cursor = Cursors.SizeWE; currentEdgeCorner = EdgeCorner.LeftEdge; } //the right edge else if (this.Width - location.X <5) { this.Cursor = Cursors.SizeWE; currentEdgeCorner = EdgeCorner.RightEdge; } //the bottom edge else if (this.Height - location.Y <5) { this.Cursor = Cursors.SizeNS; currentEdgeCorner = EdgeCorner.BottomEdge; } //the top edge else if (location.Y <5) { this.Cursor = Cursors.SizeNS; currentEdgeCorner = EdgeCorner.TopEdge; } else { this.Cursor = Cursors.Arrow; currentEdgeCorner = EdgeCorner.Center; }
2. 在控件的mousemove事件里视情况设置高度，宽度，位置信息：
2.1 当移动右边框时，只需要改变宽度。
2.2 当移动左边框时，在改变宽度的同时要改变控件的位置：当宽度增加向量△，那么Canvas.Left要减少向量△。
2.3 其他位置同理：
Point _current = e.GetPosition(this.Parent as UIElement); double newHeight = this.Height; double newWidth = this.Width; if (this.Cursor == Cursors.SizeWE) { if (currentEdgeCorner == EdgeCorner.RightEdge) { newWidth = orgSize.X + (_current.X - _rootPosition.X); if (newWidth < 5) return; } else { newWidth = orgSize.X - (_current.X - _rootPosition.X); if (newWidth < 5) return; this.SetValue(Canvas.LeftProperty, orgLoc.X + (_current.X - _rootPosition.X)); } } if (this.Cursor == Cursors.SizeNS) { if (currentEdgeCorner == EdgeCorner.BottomEdge) { newHeight = orgSize.Y + (_current.Y - _rootPosition.Y); if (newHeight < 5) return; } else { newHeight = orgSize.Y - (_current.Y - _rootPosition.Y); if (newHeight < 5) return; this.SetValue(Canvas.TopProperty, orgLoc.Y + (_current.Y - _rootPosition.Y)); } } if (this.Cursor == Cursors.SizeNESW) { if (currentEdgeCorner == EdgeCorner.RightTopCorner) { newHeight = orgSize.Y - (_current.Y - _rootPosition.Y); newWidth = orgSize.X + (_current.X - _rootPosition.X); if (newHeight < 5 || newWidth < 5) return; this.SetValue(Canvas.TopProperty, orgLoc.Y + (_current.Y - _rootPosition.Y)); } else { newHeight = orgSize.Y + (_current.Y - _rootPosition.Y); newWidth = orgSize.X - (_current.X - _rootPosition.X); if (newHeight < 5 || newWidth < 5) return; this.SetValue(Canvas.LeftProperty, orgLoc.X + (_current.X - _rootPosition.X)); } } if (this.Cursor == Cursors.SizeNWSE) { if (currentEdgeCorner == EdgeCorner.LeftTopCorner) { newHeight = orgSize.Y - (_current.Y - _rootPosition.Y); newWidth = orgSize.X - (_current.X - _rootPosition.X); if (newHeight < 5 || newWidth < 5) return; this.SetValue(Canvas.TopProperty, orgLoc.Y + (_current.Y - _rootPosition.Y)); this.SetValue(Canvas.LeftProperty, orgLoc.X + (_current.X - _rootPosition.X)); } else { newHeight = orgSize.Y + (_current.Y - _rootPosition.Y); newWidth = orgSize.X + (_current.X - _rootPosition.X); if (newHeight < 5 || newWidth < 5) return; } } this.Height = newHeight; this.Width = newWidth;
当要设置位置信息Canvas.Top, Canvas.Left时，必须特别用此控件的父类或者其他不动点的相对值，即
Point _current = e.GetPosition(this.Parent as UIElement);
是正确的，但
Point _current = e.GetPosition(this);
是不正确的。