inno-setup – Inno设置：检查新的更新

我已经看到了一些用于比较版本字符串的函数,例如在this script中使用的那个,但我决定写自己的.它可以检测到无效的版本字符串,并将丢失的版本块视为0,这会导致比较如下所示的版本字符串：

1.2.3
1.2.3.0.0.0

以下脚本可能会执行您想要的操作(安装版本由AppVersion指令定义)：

[Setup]
AppName=My Program
AppVersion=1.2.3
DefaultDirName={pf}My Program

[Code]
const
  SetupURL = 'http://dex.wotanksmods.com/setup.exe';
  VersionURL = 'http://dex.wotanksmods.com/latestver.txt';

type
  TIntegerArray = array of Integer;
  TCompareResult = (
    crLesser,crEquals,crGreater
  );

function Max(A,B: Integer): Integer;
begin
  if A > B then Result := A else Result := B;
end;

function CompareValue(A,B: Integer): TCompareResult;
begin
  if A = B then
    Result := crEquals
  else
  if A < B then
    Result := crLesser
  else
    Result := crGreater;
end;

function AddVersionChunk(const S: string; var A: TIntegerArray): Integer;
var
  Chunk: Integer;
begin
  Chunk := StrToIntDef(S,-1);
  if Chunk <> -1 then
  begin
    Result := GetArrayLength(A) + 1;
    SetArrayLength(A,Result);
    A[Result - 1] := Chunk;
  end
  else
    RaiseException('Invalid format of version string');
end;

function ParseVersionStr(const S: string; var A: TIntegerArray): Integer;
var
  I: Integer;
  Count: Integer;
  Index: Integer;
begin
  Count := 0;
  Index := 1;

  for I := 1 to Length(S) do
  begin
    case S[I] of
      '.':
      begin
        AddVersionChunk(Copy(S,Index,Count),A);
        Count := 0;
        Index := I + 1;
      end;
      '0','1','2','3','4','5','6','7','8','9':
      begin
        Count := Count + 1;
      end;
    else
      RaiseException('Invalid char in version string');
    end;
  end;
  Result := AddVersionChunk(Copy(S,A);
end;

function GetVersionValue(const A: TIntegerArray; Index,Length: Integer): Integer;
begin
  Result := 0;
  if (Index >= 0) and (Index < Length) then
    Result := A[Index];
end;

function CompareVersionStr(const A,B: string): TCompareResult;
var
  I: Integer;
  VerLenA,VerLenB: Integer;
  VerIntA,VerIntB: TIntegerArray;
begin
  Result := crEquals;

  VerLenA := ParseVersionStr(A,VerIntA);
  VerLenB := ParseVersionStr(B,VerIntB);

  for I := 0 to Max(VerLenA,VerLenB) - 1 do
  begin
    Result := CompareValue(GetVersionValue(VerIntA,I,VerLenA),GetVersionValue(VerIntB,VerLenB));
    if Result <> crEquals then
      Exit;
  end;
end;

function DownloadFile(const URL: string; var Response: string): Boolean;
var
  WinHttpRequest: Variant;
begin
  Result := True;
  try
    WinHttpRequest := CreateOleObject('WinHttp.WinHttpRequest.5.1');
    WinHttpRequest.Open('GET',URL,False);
    WinHttpRequest.Send;
    Response := WinHttpRequest.ResponseText;
  except
    Result := False;
    Response := GetExceptionMessage;
  end;
end;

function InitializeSetup: Boolean;
var
  ErrorCode: Integer;
  SetupVersion: string;
  LatestVersion: string;
begin
  Result := True;

  if DownloadFile(VersionURL,LatestVersion) then
  begin
    SetupVersion := '{#SetupSetting('AppVersion')}';
    if CompareVersionStr(LatestVersion,SetupVersion) = crGreater then
    begin
      if MsgBox('There is a newer version of this setup available. Do ' +
        'you want to visit the site ?',mbConfirmation,MB_YESNO) = IDYES then
      begin
        Result := not ShellExec('',SetupURL,'',SW_SHOW,ewNoWait,ErrorCode);
      end;
    end;
  end;
end;