我没分，可是我有问题：Canvas does not allow drawing;

Question

首先我用这个函数画一个矩形
DrawRec(Form4.Button1.Left,Form4.Button1.top+i*Height,Form4.Button1.Width,Height)procedure DrawRec(left,top,width,Height:Integer);
var
  Rect:TRect;
Begin
  Rect.Left:=left;
  Rect.Top:=top;
  Rect.Right:=left+Width;
  Rect.Bottom:=top+Height;
  Canvas.MoveTo(left,top);
  Canvas.LineTo(left,top+Height);
  Canvas.LineTo(left+width,top+Height);
  Canvas.LineTo(left+Width,top);
  Canvas.LineTo(left,top);
  Canvas.FillRect(Rect);
End;
当程序运行到Canvas.LineTo(left,top+Height)的时候，出现上述错误~
救救我吧

Answer 1

procedure DrawRec(left,top,width,Height:Integer);CanvasDrawRec是一个类过程吗？Canvas是谁的Canvas呀？