Question

编写一个delphi根据三角形的三个顶点画出一个三角形

Answer 1

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs;

type
  TForm1 = class(TForm)
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  q:array[1..3,1..2]of longint;
  flag:boolean;
  n:longint;

implementation

{$R *.dfm}

procedure drawTriangle();
begin
  form1.Canvas.MoveTo(q[1,1],q[1,2]);
  form1.Canvas.LineTo(q[2,1],q[2,2]);
  form1.Canvas.MoveTo(q[2,1],q[2,2]);
  form1.Canvas.LineTo(q[3,1],q[3,2]);
  form1.Canvas.MoveTo(q[3,1],q[3,2]);
  form1.Canvas.LineTo(q[1,1],q[1,2]);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  flag:=false;
  n:=0;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  inc(n);
  if n=4 then n:=1;
  q[n,1]:=x;
  q[n,2]:=y;
  if (not flag) and (n=3) then flag:=true;

  self.Repaint;
  if flag then drawTriangle();

end;

end.

Unit主代码

其他的你会自己弄吧，也没用什么控件

纯正Delphi哦，Delphi XE5下编写

使用方法，Form生成之后直接在Form上面点三个点，就画出了这三个点的三角形，是不是很方便呢

Answer 2

用lazarus编制，和delphi类似，x坐标不超过900，y坐标不超过600。若超过，同比例缩小即可。

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

{ TForm1 }

TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
Edit2: TEdit;
Edit3: TEdit;
Edit4: TEdit;
Edit5: TEdit;
Edit6: TEdit;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ private declarations }
public
{ public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin

end;

procedure TForm1.Button1Click(Sender: TObject);
var
x1,y1,x2,y2,x3,y3:real;
begin
val(edit1.Text,x1);
val(edit2.text,y1);
val(edit3.text,x2);
val(edit4.text,y2);
val(edit5.Text,x3);
val(edit6.text,y3);
canvas.Line(trunc(x1),600-trunc(y1),trunc(x2),600-trunc(y2));
canvas.Line(trunc(x1),600-trunc(y1),trunc(x3),600-trunc(y3));
canvas.Line(trunc(x2),600-trunc(y2),trunc(x3),600-trunc(y3));
end;

end.