Delphi做验证码登录窗口

在五月麦田的帮助下做成了，感觉挺好，验证码输入的时候需要大写：

组件：LabelEdit 3个  Button 2个  image 1个。

　　

代码如下：

　　

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    LabeledEdit1: TLabeledEdit;
    LabeledEdit2: TLabeledEdit;
    LabeledEdit3: TLabeledEdit;
    Button1: TButton;
    Button2: TButton;
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Image1Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    function DrawImg(img: TImage): string;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
var
  str:string;
implementation

{$R *.dfm}

function TForm1.DrawImg(img: TImage): string;      //画出验证码函数
var
  I,j,k:   Integer;
  vPoint:   TPoint;
  vLeft:   Integer;
  arrStr:array [..]of string ;
  strResult: string;
begin
  strResult := '';
  arrStr[] := '';  arrStr[]:='';  arrStr[]:='';  arrStr[]:='';
  arrStr[] := '';  arrStr[]:='';  arrStr[]:='';  arrStr[]:='';
  arrStr[] := '';  arrStr[]:=''; arrStr[]:='A'; arrStr[]:='B';
  arrStr[] := 'C'; arrStr[]:='D'; arrStr[]:='E'; arrStr[]:='F';
  arrStr[] := 'G'; arrStr[]:='H'; arrStr[]:='I'; arrStr[]:='J';
  arrStr[] := 'K'; arrStr[]:='L'; arrStr[]:='M'; arrStr[]:='N';
  arrStr[] := 'O'; arrStr[]:='P'; arrStr[]:='Q'; arrStr[]:='R';
  arrStr[] := 'S'; arrStr[]:='T'; arrStr[]:='U'; arrStr[]:='V';
  arrStr[] := 'W'; arrStr[]:='X'; arrStr[]:='Y'; arrStr[]:='Z';
  For j:= to   do
  begin
    Randomize;
    k := strtoint(Format('%.1d',[Random()]));
    strResult := strResult + trim(arrStr[k])
  end;
  vLeft := ;
  img.picture := nil;
  for I :=  to Length(strResult) do
  begin
    with Img do
    begin
      Canvas.Font.Size := Random()+ ;
      Canvas.Font.Color := RGB(Random() and $C0,
      Random() and $C0, Random() and $C0);
      if Random()= then
        Canvas.Font.Style := [fsBold]
      else Canvas.Font.Style := [];
      begin
        Canvas.Font.Name := Screen.Fonts[];
        vPoint.X := Random()+ vLeft;
        vPoint.Y := Random();
        Canvas.TextOut(vPoint.X, vPoint.Y,strResult[I]);
        vLeft := vPoint.X + Canvas.TextWidth(strResult[I]);
      end;
    end;
  end;
  result := strResult;    //返回值
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
  str := DrawImg(Image1);
end;

procedure TForm1.Image1Click(Sender: TObject);
begin
  str := DrawImg(Image1);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if (LabeledEdit1.Text = 'Hello') and (LabeledEdit2.Text = 'world') and (LabeledEdit3.Text = str) then
    MessageBox(Handle, '登陆成功！', '提示', MB_OK);

  if LabeledEdit1.Text <> 'Hello' then
    begin
    MessageBox(Handle, '用户名错误,请重新输入！', '提示', MB_OK);
    LabeledEdit1.Text := '';
    LabeledEdit2.Text := '';
    LabeledEdit3.Text := '';
    str := DrawImg(Image1);
    end

  else if LabeledEdit2.Text <> 'world' then
    begin
    MessageBox(Handle, '密码错误,请重新输入！', '提示', MB_OK);
    LabeledEdit1.Text := '';
    LabeledEdit2.Text := '';
    LabeledEdit3.Text := '';
    str := DrawImg(Image1);
    end

  else if LabeledEdit3.Text <> str then
    begin
    MessageBox(Handle, '验证码错误,请重新输入！', '提示', MB_OK);
    LabeledEdit1.Text := '';
    LabeledEdit2.Text := '';
    LabeledEdit3.Text := '';
    str := DrawImg(Image1);
    end;
end;

procedure TForm1.Button2Click(Sender: TObject);   //退出
begin
  close;
end;

end.

其实也可以这样写：

　　

　　代码如下：

　　

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
arrStr:array [..]of string ;
begin
  arrStr[] := '';  arrStr[]:='';  arrStr[]:='';  arrStr[]:='';
  arrStr[] := '';  arrStr[]:='';  arrStr[]:='';  arrStr[]:='';
  arrStr[] := '';  arrStr[]:=''; arrStr[]:='A'; arrStr[]:='B';
  arrStr[] := 'C'; arrStr[]:='D'; arrStr[]:='E'; arrStr[]:='F';
  arrStr[] := 'G'; arrStr[]:='H'; arrStr[]:='I'; arrStr[]:='J';
  arrStr[] := 'K'; arrStr[]:='L'; arrStr[]:='M'; arrStr[]:='N';
  arrStr[] := 'O'; arrStr[]:='P'; arrStr[]:='Q'; arrStr[]:='R';
  arrStr[] := 'S'; arrStr[]:='T'; arrStr[]:='U'; arrStr[]:='V';
  arrStr[] := 'W'; arrStr[]:='X'; arrStr[]:='Y'; arrStr[]:='Z';
  Image1.Canvas.TextOut( ,,arrStr[random()]);
  Image1.Canvas.TextOut(,,arrStr[random()]);
  Image1.Canvas.TextOut(,,arrStr[random()]);
  Image1.Canvas.TextOut(,,arrStr[random()]);
end;

end