Adding characters one by one in TMemo

Question

Can someone tell me how to add characters from one text file to the memo? A text file contains various paragraphs of texts. I want to add the characters of each paragraph one by one to the end of the paragraph. Then after 10 seconds, run the next paragraph, which will be shown in the memo.

Thanks Sei

Answer 1

You would TTimer use TTimer . Drop the TTimer , a TMemo and a TButton in your form. Then do

 var lines: TStringList; pos: TPoint; const CHAR_INTERVAL = 75; PARAGRAPH_INTERVAL = 1000; procedure TForm6.Button1Click(Sender: TObject); const S_EMPTY_FILE = 'You are trying to display an empty file!'; begin Memo1.ReadOnly := true; Memo1.Clear; Memo1.Lines.Add(''); pos := Point(0, 0); if lines.Count = 0 then raise Exception.Create(S_EMPTY_FILE); while (pos.Y < lines.Count) and (length(lines[pos.Y]) = 0) do inc(pos.Y); if pos.Y = lines.Count then raise Exception.Create(S_EMPTY_FILE); NextCharTimer.Enabled := true; end; procedure TForm6.FormCreate(Sender: TObject); begin lines := TStringList.Create; lines.LoadFromFile('C:\Users\Andreas Rejbrand\Desktop\Test.txt'); end; procedure TForm6.NextCharTimerTimer(Sender: TObject); begin NextCharTimer.Interval := CHAR_INTERVAL; Memo1.Lines[Memo1.Lines.Count - 1] := Memo1.Lines[Memo1.Lines.Count - 1] + lines[pos.Y][pos.X + 1]; inc(pos.X); if pos.X = length(lines[pos.Y]) then begin NextCharTimer.Interval := PARAGRAPH_INTERVAL; pos.X := 0; repeat inc(pos.Y); Memo1.Lines.Add(''); until (pos.Y = lines.Count) or (length(lines[pos.Y]) > 0); end; if pos.Y = lines.Count then NextCharTimer.Enabled := false; end; 

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Answer 2

A thread alternative to a timer. Checks the "carriage return" in the file for the paragraph:

 const UM_MEMOCHAR = WM_USER + 22; type TForm1 = class(TForm) Memo1: TMemo; Button1: TButton; procedure Button1Click(Sender: TObject); private procedure UMMemoChar(var Msg: TMessage); message UM_MEMOCHAR; public end; var Form1: TForm1; implementation {$R *.dfm} type TCharSender = class(TThread) private FCharWait, FParWait: Integer; FFormHandle: HWND; FFS: TFileStream; protected procedure Execute; override; public constructor Create(FileName: string; CharWait, ParagraphWait: Integer; FormHandle: HWND); destructor Destroy; override; end; constructor TCharSender.Create(FileName: string; CharWait, ParagraphWait: Integer; FormHandle: HWND); begin FCharWait := CharWait; FParWait := ParagraphWait; FFormHandle := FormHandle; FFS := TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite); FreeOnTerminate := True; inherited Create(False); end; destructor TCharSender.Destroy; begin FFS.Free; inherited; end; procedure TCharSender.Execute; var C: Char; begin while (FFS.Position < FFS.Size) and not Terminated do begin FFS.Read(C, SizeOf(C)); if (C <> #10) then PostMessage(FFormHandle, UM_MEMOCHAR, Ord(C), 0); if C = #13 then Sleep(FParWait) else Sleep(FCharWait); end; end; {TForm1} procedure TForm1.Button1Click(Sender: TObject); begin Memo1.Clear; TCharSender.Create( ExtractFilePath(Application.ExeName) + 'text.txt', 20, 1000, Handle); end; procedure TForm1.UMMemoChar(var Msg: TMessage); begin Memo1.SelStart := Memo1.Perform(WM_GETTEXTLENGTH, 0, 0); Memo1.Perform(WM_CHAR, Msg.WParam, 0); end; 

Answer 3

There are many ways to do this, and I'm not sure how you are going to process newlines. However, all routes lead to TMemo.Lines , which is an instance of TStrings that completes the Windows messages needed to interact with the basic Windows editing control.

For example, these procedures should get started.

 procedure AddNewLine(Memo: TMemo); begin Memo.Lines.Add(''); end; procedure AddCharacter(Memo: TMemo; const C: Char); var Lines: TStrings; begin Lines := Memo.Lines; if Lines.Count=0 then AddNewLine(Memo); Lines[Lines.Count-1] := Lines[Lines.Count-1]+C; end;