Polygon、Polyline、PolyBezier、PolyBezierTo

---Polygon、Polyline

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Canvas.Pen.Width := 2;
  Canvas.Pen.Color := clRed;
  Canvas.Brush.Color := clYellow;
end;

{绘制多边形; 它的参数是一个点数组, 这里定义了一个常数数组}
procedure TForm1.Button1Click(Sender: TObject);
const
  pts: array[0..3] of TPoint = (
    (x:10; y:40),
    (x:46; y:120),
    (x:82; y:40),
    (x:46; y:10)
  );
begin
  Canvas.Polygon(pts);
end;

{绘制连续的一组直线; 它的参数也是一个点数组, 我只是把上面的平移了一点}
procedure TForm1.Button2Click(Sender: TObject);
const
  pts: array[0..3] of TPoint = (
    (x:10+82; y:40),
    (x:46+82; y:120),
    (x:82+82; y:40),
    (x:46+82; y:10)
  );
begin
  Canvas.Polyline(pts);
end;

end.


//效果图:

--PolyBezier、PolyBezierTo

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{PolyBezier 至少需要四个点做参数; 不改变画笔的当前位置}
procedure TForm1.Button1Click(Sender: TObject);
var
  pts: array[0..3] of TPoint;
begin
  Canvas.Pen.Width := 2;
  Canvas.Pen.Color := clRed;

  pts[0].X := 10; pts[0].Y := 10;  {起点}
  pts[1].X := 60; pts[1].Y := 10;  {控制点1}
  pts[2].X := 10; pts[2].Y := 100; {控制点2}
  pts[3].X := 60; pts[3].Y := 100; {终点}

  Canvas.PolyBezier(pts);

  Canvas.Pen.Width := 1;
  Canvas.Pen.Color := clWhite;
  Canvas.LineTo(ClientWidth, ClientHeight);
end;

{PolyBezierTo 最少只需要需要三个点, 它把当前位置当作第一点; 会改变画笔的当前位置}
procedure TForm1.Button2Click(Sender: TObject);
var
  pts: array[1..3] of TPoint; {从 1 开始的, 就 3 个元素}
begin
  Canvas.Pen.Width := 2;
  Canvas.Pen.Color := clRed;

  Canvas.MoveTo(10 + 82, 10);           {起点}

  //pts[0].X := 10; pts[0].Y := 10;
  pts[1].X := 60 + 82; pts[1].Y := 10;  {控制点1}
  pts[2].X := 10 + 82; pts[2].Y := 100; {控制点2}
  pts[3].X := 60 + 82; pts[3].Y := 100; {终点}

  Canvas.PolyBezierTo(pts);

  Canvas.Pen.Width := 1;
  Canvas.Pen.Color := clBlue;
  Canvas.LineTo(ClientWidth, ClientHeight);
end;

end.


//效果图:

---

//绘制多条贝塞尔线时, 每条线的终点也是下条线的起点.

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{PolyBezier 绘制多条线时, 需要 3*x + 1 个点}
procedure TForm1.Button1Click(Sender: TObject);
var
  pts: array[0..6] of TPoint;
begin
  Canvas.Pen.Width := 2;
  Canvas.Pen.Color := clRed;

  pts[0].X := 10; pts[0].Y := 10;
  pts[1].X := 60; pts[1].Y := 10;
  pts[2].X := 10; pts[2].Y := 100;
  pts[3].X := 40; pts[3].Y := 100;
  pts[4].X := 100; pts[4].Y := 10;
  pts[5].X := 55; pts[5].Y := 99;
  pts[6].X := 70; pts[6].Y := 10;

  Canvas.PolyBezier(pts);
end;

{PolyBezierTo 绘制多条线时, 需要 3*x 个点}
procedure TForm1.Button2Click(Sender: TObject);
var
  pts: array[1..6] of TPoint;
begin
  Canvas.Pen.Width := 2;
  Canvas.Pen.Color := clRed;

  Canvas.MoveTo(10 + 82, 10);

  //pts[0].X := 10; pts[0].Y := 10;
  pts[1].X := 60 + 82; pts[1].Y := 10;
  pts[2].X := 10 + 82; pts[2].Y := 100;
  pts[3].X := 40 + 82; pts[3].Y := 100;
  pts[4].X := 100 + 82; pts[4].Y := 10;
  pts[5].X := 55 + 82; pts[5].Y := 99;
  pts[6].X := 70 + 82; pts[6].Y := 10;

  Canvas.PolyBezierTo(pts);
end;

end.


//效果图: