Inno Setup: Check for New Updates

Question

After reading this post How to read a text file from an Internet resource? , I adapted the code to what I need, but I have some problems.

What I want to do is that when the installation starts, it checks for new updates. 1) If there is no new update, do not show any messages. 2) And if there is a new update, show a message asking if you want to download it or not.

This is my code:

procedure InitializeWizard;
var
  DxLastVersion: string;
  DxSetupVersion: String;

begin
  if DownloadFile('http://dex.wotanksmods.com/latestver.txt', DxLastVersion)  then
    MsgBox(DxLastVersion, mbInformation, MB_YESNO)
  else
    MsgBox(DxLastVersion, mbError, MB_OK)
end;

Thanks a lot for advanced.

Answer 1

, , , . Inno Setup , .

, , . , this script, . 0, , , , :

1.2.3
1.2.3.0.0.0

script , ( AppVersion):

[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, Index, Count), 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, I, 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;