Delphi 后端随机生成前端验证码图片程序源代码,开箱即用

Delphi 后端随机生成前端验证码图片程序源代码,开箱即用_第1张图片

 在前端开发的时候,常用的一个需求就是图形验证码,那么如果后端使用Delphi开发,随机生成一个验证码图片,是如何实现呢?

其实如果是VCL,就是调用TBitMap对象来实现,TBitMap有详细的Canvas操作函数,具体的操作参见Delphi的帮助文档。

直接上源代码如下:

{*******************************************************
生成验证码图片: 2023-04-07
作者:sensor(老吴)QQ:910731685
将生成的图片转换成png格式,减少传输数据量。
如果是BMP图片,样本:19KB,转换成png后大小为:3KB
*******************************************************}
unit uSZHN_VerifyCode;

interface
uses
  System.Classes,
  System.SysUtils,
  VCL.Graphics,
  System.UIConsts,
  System.UITypes,
  Vcl.ExtCtrls,
//  Vcl.Imaging.jpeg,
  Vcl.Imaging.pngimage,
  System.Types;

type
  // 生成验证码组件
  TSZHN_GenerateVerifyCode = class
  private const
    // 定义字典表,不要零(0),因为零和字母O样子太接近
     arrStr: array [0 .. 42] of char = (
      '1','2','3','4','5','6','7','8','9',
      'A','B','C','D','E','F','G','H','I',
      'J','K','L','M','N','O','P','Q','R',
      'S','T','U','V','W','X','Y','Z','我','爱','中','国','科','技','畅','想');
  private
    FBitmapWidth:   integer;      // 图片宽度
    FBitmapHeight:  integer;      // 图片高度
    FCodeCount:     integer;      // 取验证码字符的个数,默认是4个字符
    FFontName:      string;       // 字体名称
    FMinFontSize:   integer;      // 最小字体大小
    FRandomLineCount: integer;    // 背景随机线条数
    FXRandomLen:    integer;      // X的随机值长度
    FYRandomLen:    integer;      // Y的随机值长度
    // 画出验证码函数
    function VerifyCodeDrawImg(BMP : TBitmap): string;
  public
    constructor Create;
    procedure GetVerifyCodeAndImage(ImageStream: TStream; var VerifyCode: string);
  published
    property Width: integer           read FBitmapWidth     write FBitmapWidth;
    property Height: integer          read FBitmapHeight    write FBitmapHeight;
    property CodeCount: integer       read FCodeCount       write FCodeCount;
    property MinFontSize: integer     read FMinFontSize     write FMinFontSize;
    property RandomLineCount: integer read FRandomLineCount write FRandomLineCount;
    property XRandomLen: integer      read FXRandomLen      write FXRandomLen;
    property YRandomLen: integer      read FYRandomLen      write FYRandomLen;
  end;


//外部调用函数,  ImageStream 参数返回的是生成的验证码图片数据流,结果为验证码字符串
function Create_VerifyCode(ImageStream: TStream): string;


implementation

//外部调用函数,  ImageStream 参数返回的是生成的验证码图片数据流,结果为验证码字符串
function Create_VerifyCode(ImageStream: TStream): string;
var
  SZHN_GenerateVerifyCode : TSZHN_GenerateVerifyCode;
begin
  SZHN_GenerateVerifyCode := TSZHN_GenerateVerifyCode.Create;
  try
    SZHN_GenerateVerifyCode.GetVerifyCodeAndImage(ImageStream, Result);
  finally
    SZHN_GenerateVerifyCode.Free;
  end;

end;


constructor TSZHN_GenerateVerifyCode.Create();
begin
  inherited;
  FBitmapWidth      := 120;
  FBitmapHeight     := 40;
  FCodeCount        := 4;
  FMinFontSize      := 4;
  FRandomLineCount  := 10;
  FXRandomLen       := 5;
  FYRandomLen       := 4;
end;

// 获取验证码和图片的流数据
procedure TSZHN_GenerateVerifyCode.GetVerifyCodeAndImage(ImageStream: TStream;
  var VerifyCode: string);
var
  BMP : TBitmap;
  PNG : TPNGImage;
begin
  BMP := TBitmap.Create;
  PNG := TPNGImage.Create;
  try
    // 默认 宽120,高40
    BMP.Width := FBitmapWidth;
    BMP.Height:= FBitmapHeight;

    //画验证码图,返回的是图形字符串
    VerifyCode := VerifyCodeDrawImg(BMP);

    //转换成png格式
    PNG.Assign(BMP);
    PNG.CompressionLevel := 9;          //最高压缩率  0..9
    PNG.SaveToStream(ImageStream);      //保存成 Stream ,以便可以传递给前端(Base64)

  finally
    FreeAndNil(BMP);
    FreeAndNil(PNG);
  end;

end;

// 画出验证码函数
function TSZHN_GenerateVerifyCode.VerifyCodeDrawImg(BMP : TBitmap): string;
var
  I, j, k: integer;
  X, Y, W, H: integer;
  vLeft: integer;
  strResult: string;

  //随机颜色函数
  function RandomColor : TColor;
  begin
    Result := Random($FF) shl 16 + Random($FF) shl 8 + Random($FF);
  end;
  //随机生成字体名字,内置6种字体随机切换
  function Random_FontName: string;
  var
    FontNames : Tarray;
  begin
    SetLength(FontNames,6);
    FontNames[0] := 'Microsoft JhengHei UI';
    FontNames[1] := '宋体';
    FontNames[2] := 'Microsoft YaHei UI';
    FontNames[3] := 'Ink Free';
    FontNames[4] := 'Malgun Gothic';
    FontNames[5] := 'Cascadia Code';
    Randomize;
    Result := FontNames[Random(1000000) mod 6];
  end;

begin
  // 随机获取字符,默认4个字符
  For j := 1 to FCodeCount do
  begin
    Randomize;
    k := Random(1000000) mod 43;
    strResult := strResult + trim(arrStr[k]);
  end;
  vLeft := 5;
  //设置背景颜色
  BMP.Canvas.Brush.Style := bsSolid;
  BMP.Canvas.Brush.Color := RandomColor;
  BMP.Canvas.FillRect(TRect.Create(0, 0, FBitmapWidth, FBitmapHeight));

  // 随机画10条线
  for j := 1 to FRandomLineCount do
  begin
    Randomize;
    BMP.Canvas.Brush.Style := bsCross;
    BMP.Canvas.Pen.Color := RandomColor;
    BMP.Canvas.Pen.Width := 1;
    BMP.Canvas.Pen.Mode  := pmXor;

    BMP.Canvas.MoveTo(Random(FBitmapWidth), Random(FBitmapHeight));
    BMP.Canvas.LineTo(Random(FBitmapWidth), Random(FBitmapHeight));
  end;

  for I := 1 to length(strResult) do
  begin
    Randomize;
    // 随机字体颜色,这里暂时不用每个字符一个随机颜色
    BMP.Canvas.Font.Color := RandomColor;
    //设置字体名字
    BMP.Canvas.Font.Name := Random_FontName;
    // 字体大小
    BMP.Canvas.Font.Size := Random(8) + FMinFontSize;
    if BMP.Canvas.Font.Size < (FMinFontSize + 5) then
      BMP.Canvas.Font.Size := BMP.Canvas.Font.Size + 5;
    if Random(2) = 1 then
      BMP.Canvas.Font.Style := [TFontStyle.fsBold]
    else
      BMP.Canvas.Font.Style := [TFontStyle.fsItalic];
    begin
      X := Random(FXRandomLen) + vLeft;
      Y := Random(FYRandomLen);
      W := BMP.Canvas.TextWidth(strResult[I]);
      H := BMP.Canvas.TextHeight(strResult[I]);

      BMP.Canvas.TextOut(X,Y,strResult[I]);
      vLeft := X + W + 1;
    end;
  end;
  Result := strResult; // 返回值 ,验证码字符串
end;

end.

具体使用代码:

uses
   uSZHN_VerifyCode;
var
   sVerifyCode : string;  //验证码字符串
   TM : TMemoryStream;    //验证码图片数据流信息
begin
   TM := TMemoryStream.Create;
   sVerifyCode := Create_VerifyCode(TM);
   TM.SaveToFile('C:\Temp\1.png');   //可以保存成文件
   Image1.Picture.LoadFromFile('C:\Temp\1.png');  //可以直接在Image1中显示出来
   TM.Free;
end;

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