WinAPI: PolylineTo - 绘制一组连续线段(更新当前位置)-优快云博客

本文介绍了使用PolylineTo函数绘制多边形的原理与实践，包括如何设置起始点及如何利用该函数更新当前位置继续绘图。通过示例代码展示了不同场景下的应用。

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//声明:
PolylineTo(
  DC: HDC;       {设备环境句柄}
  var Points;    {点数组}
  Count: Integer {数组元素个数}
): BOOL;


//如果不给 PolylineTo 指定起点, 将默认 0 点位起点
procedure TForm1.FormPaint(Sender: TObject);
var
  ps: array[0..5] of TPoint;
begin
  ps[0].X := 50;
  ps[0].Y := 50;
  ps[1].X := 100;
  ps[1].Y := 50;
  ps[2].X := 125;
  ps[2].Y := 75;
  ps[3].X := 100;
  ps[3].Y := 100;
  ps[4].X := 50;
  ps[4].Y := 100;
  ps[5].X := 25;
  ps[5].Y := 75;

  PolylineTo(Canvas.Handle, ps, 6);
end;

 
//效果图:

//给 PolylineTo 指定起点
procedure TForm1.FormPaint(Sender: TObject);
var
  ps: array[0..4] of TPoint;
begin
  MoveToEx(Canvas.Handle, 50,50, nil);
  
  ps[0].X := 100;
  ps[0].Y := 50;
  ps[1].X := 125;
  ps[1].Y := 75;
  ps[2].X := 100;
  ps[2].Y := 100;
  ps[3].X := 50;
  ps[3].Y := 100;
  ps[4].X := 25;
  ps[4].Y := 75;

  PolylineTo(Canvas.Handle, ps, 5);
end; 


//效果图:

//PolylineTo 更新当前位置
procedure TForm1.FormPaint(Sender: TObject);
var
  ps: array[0..4] of TPoint;
begin
  MoveToEx(Canvas.Handle, 50,50, nil);
  
  ps[0].X := 100;
  ps[0].Y := 50;
  ps[1].X := 125;
  ps[1].Y := 75;
  ps[2].X := 100;
  ps[2].Y := 100;
  ps[3].X := 50;
  ps[3].Y := 100;
  ps[4].X := 25;
  ps[4].Y := 75;

  PolylineTo(Canvas.Handle, ps, 5);

  {PolylineTo 更新当前位置, 继续画}
  LineTo(Canvas.Handle, 50,50);
end;


//效果图: