WinAPI: Arc - 绘制弧线

//声明:

Arc(

  DC: HDC;                                {设备环境句柄}

  X1, Y1, X2, Y2, X3, Y3, X4, Y4: Integer {四个坐标点}

): BOOL;




 
   




//举例:

procedure TForm1.FormPaint(Sender: TObject);

const

  x1 = 10;

  y1 = 10;

  x2 = 200;

  y2 = 200;

  x3 = 130;

  y3 = 200;

  x4 = 160;

  y4 = 10;

begin

  Canvas.TextOut(x1,y1, '1');

  Canvas.TextOut(x2,y2, '2');

  Canvas.TextOut(x3,y3, '3');

  Canvas.TextOut(x4,y4, '4');

  

  Arc(Canvas.Handle, x1,y1, x2,y2, x3,y3, x4,y4);

end;


 
   




//效果图:

---

//书上的一个例子:

procedure TForm1.FormPaint(Sender: TObject);

var

  i: Integer;

  r: TRect;

begin

  r := Self.ClientRect;

  Canvas.Pen.Width := 2;



  for i := 1 to 5 do

  begin

    Arc(Canvas.Handle,

        r.Left, r.Top,

        r.Right, r.Bottom,

        r.Right, (r.Bottom - r.Top) div 2,

        r.Left, (r.Bottom - r.Top) div 2

    );



    InflateRect(r, -2, -2);                 {缩小矩形}

    Canvas.Pen.Color := PaletteIndex(i+10); {改变颜色}

  end;

end;


 
   




//效果图:

---