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//把 PaintBox 放到 ScrollBox 里
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
  randomize(); //初始化随机数
  ScrollBox1->DoubleBuffered=true;
}
//---------------------------------------------------------------------------
int dx=0,xs[1000]; //最多显示1000个点
int dy=0,ys[1000];
int nn=0;
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
  if(nn<1000)
   {
     xs[nn]=(dx+=random(10));
     ys[nn]=(dy+=random(10));
     nn++;
     if(dx>PaintBox1->Width)PaintBox1->Width=dx;
     if(dy>PaintBox1->Height)PaintBox1->Height=dy;
     PaintBox1->Invalidate();
   }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::PaintBox1Paint(TObject *Sender)
{
  TRect rc(0,0,PaintBox1->Width,PaintBox1->Height);
  PaintBox1->Canvas->Brush->Color=clWhite;
  PaintBox1->Canvas->FillRect(rc);
  PaintBox1->Canvas->MoveTo(xs[0],ys[0]);
  for(int i=1; i    PaintBox1->Canvas->LineTo(xs[i],ys[i]);
}
//---------------------------------------------------------------------------

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