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Text Editing and Sources

TTMSFNCMemo exposes the full set of text-manipulation operations you would expect from a code editor, plus a multi-source model for switching between open files without losing per-file state.

Loading and saving text

Set Text or Lines directly, or load from file or URL:

Loading and saving textPascalC++
TMSFNCMemo1.LoadFromFile('C:\Projects\unit1.pas');
TMSFNCMemo1.LoadFromURL('https://example.com/main.js');
// Save: write Text to a TStringList or file yourself
TFile.WriteAllText('out.pas', TMSFNCMemo1.Text);

TMSFNCMemo1->LoadFromFile("C:\\Projects\\unit1.pas");
TMSFNCMemo1->LoadFromURL("https://example.com/main.js");
// Save: write Text to a TStringList or file yourself
System::Ioutils::TFile::WriteAllText("out.pas", TMSFNCMemo1->Text);

LoadFromFile automatically selects the language by matching the file extension against LanguageFileExtensionsMap.

Clipboard, selection, undo/redo

Memo editingPascalC++
// --- Text content ---
TMSFNCMemo1.Text := 'begin' + sLineBreak + '  WriteLn(''Hello'');' + sLineBreak + 'end.';
TMSFNCMemo1.Lines.Add('// added line');

// Load and save
TMSFNCMemo1.LoadFromFile('C:\Projects\code.pas');
// (save is handled by writing TMSFNCMemo1.Text to a file)

// --- Clipboard ---
TMSFNCMemo1.CopyToClipBoard;
TMSFNCMemo1.PasteFromClipBoard;
TMSFNCMemo1.CutToClipBoard;
TMSFNCMemo1.SelectAll;
TMSFNCMemo1.Unselect;
TMSFNCMemo1.Undo;
TMSFNCMemo1.Redo;
TMSFNCMemo1.FormatDocument;

// --- Selection ---
TMSFNCMemo1.SelStart  := 0;
TMSFNCMemo1.SelLength := 10;
ShowMessage(TMSFNCMemo1.SelText);
TMSFNCMemo1.DeleteSelection;

// --- Multi-source editing ---
// Add sources programmatically
TMSFNCMemo1.Sources.AddSource('program Project1;', mlPascal, 'project1.dpr');
TMSFNCMemo1.Sources.AddSource('{"key": "value"}', mlJson, 'config.json');
TMSFNCMemo1.Sources.AddSourceFromFile('C:\Projects\unit1.pas');

// Switch between sources (0-based index)
TMSFNCMemo1.ActiveSource := 1;

// Add all files in a folder
TMSFNCMemo1.AddSourcesFromFolder('C:\Projects\src\');

// --- File extension → language mapping ---
// Add a custom extension for an existing language
with TMSFNCMemo1.LanguageFileExtensionsMap.Add do
begin
  Language  := mlCpp;
  Extension := '.cu';   // CUDA source files
end;

// --- Drag and drop (FMX) ---
procedure TForm1.TMSFNCMemo1DragDrop(Sender: TObject; const Data: TDragObject;
  const Point: TPointF);
var
  obj: TTMSFNCMemoDragObject;
begin
  obj := Data.Source as TTMSFNCMemoDragObject;
  if obj.Kind = otText then
    TMSFNCMemo1.Lines.Add(obj.Text)
  else if obj.Files.Count > 0 then
    obj.Files[0].Open;
end;

// Load and save
void __fastcall TForm1::LoadAndClipboard()
{
  TMSFNCMemo1->LoadFromFile("C:\\Projects\\code.pas");
  // (save is handled by writing TMSFNCMemo1->Text to a file)

  // --- Clipboard ---
  TMSFNCMemo1->CopyToClipBoard();
  TMSFNCMemo1->PasteFromClipBoard();
  TMSFNCMemo1->CutToClipBoard();
  TMSFNCMemo1->SelectAll();
  TMSFNCMemo1->Unselect();
  TMSFNCMemo1->Undo();
  TMSFNCMemo1->Redo();
  TMSFNCMemo1->FormatDocument();

  // --- Selection ---
  TMSFNCMemo1->SelStart = 0;
  TMSFNCMemo1->SelLength = 10;
  ShowMessage(TMSFNCMemo1->SelText);
  TMSFNCMemo1->DeleteSelection();
}

void __fastcall TForm1::MultiSource()
{
  // --- Multi-source editing ---
  // Add sources programmatically
  TMSFNCMemo1->Sources->AddSource("program Project1;", mlPascal, "project1.dpr");
  TMSFNCMemo1->Sources->AddSource("{\"key\": \"value\"}", mlJSON, "config.json");
  TMSFNCMemo1->Sources->AddSourceFromFile("C:\\Projects\\unit1.pas");

  // Switch between sources (0-based index)
  TMSFNCMemo1->ActiveSource = 1;

  // Add all files in a folder
  TMSFNCMemo1->AddSourcesFromFolder("C:\\Projects\\src\\");

  // --- File extension -> language mapping ---
  // Add a custom extension for an existing language
  TTMSFNCMemoLanguageFileExtensionMapItem *item = TMSFNCMemo1->LanguageFileExtensionsMap->Add();
  item->Language = mlCpp;
  item->Extension = ".cu";   // CUDA source files
}

// --- Drag and drop (FMX) ---
void __fastcall TForm1::TMSFNCMemo1DragDrop(TObject *Sender, const TDragObject &Data,
  const TPointF &Point)
{
  TTMSFNCMemoDragObject *obj = dynamic_cast<TTMSFNCMemoDragObject*>(Data.Source);
  if (obj->Kind == otText)
    TMSFNCMemo1->Lines->Add(obj->Text);
  else if (obj->Files->Count > 0)
    obj->Files->Items[0]->Open();
}
TTMSFNCMemo with Pascal syntax highlighting

Sources — editing multiple files

Sources is an ordered collection of TTMSFNCMemoSource items. Each source retains its own Language, Text, CaretPosition, breakpoints, bookmarks, and line highlights when you switch away from it.

Sources — editing multiple filesPascalC++
// Add sources
TMSFNCMemo1.Sources.AddSource('',   mlPascal, 'Unit1.pas');
TMSFNCMemo1.Sources.AddSource('{}', mlJson,   'config.json');
TMSFNCMemo1.Sources.AddSourceFromFile('C:\Projects\module.ts');
TMSFNCMemo1.AddSourcesFromFolder('C:\Projects\src\');

// Switch the active source (0-based index)
TMSFNCMemo1.ActiveSource := 1;

// Add sources
TMSFNCMemo1->Sources->AddSource("", mlPascal, "Unit1.pas");
TMSFNCMemo1->Sources->AddSource("{}", mlJSON, "config.json");
TMSFNCMemo1->Sources->AddSourceFromFile("C:\\Projects\\module.ts");
TMSFNCMemo1->AddSourcesFromFolder("C:\\Projects\\src\\");

// Switch the active source (0-based index)
TMSFNCMemo1->ActiveSource = 1;

TTMSFNCMemoSource also exposes its own SaveToFile for writing individual files back:

Sources — editing multiple filesPascalC++
TMSFNCMemo1.Sources[0].SaveToFile('C:\Projects\unit1.pas');

TMSFNCMemo1->Sources->Items[0]->SaveToFile("C:\\Projects\\unit1.pas");

File extension to language mapping

TTMSFNCMemo ships with built-in extension mappings (e.g. .pas → Pascal, .ts → TypeScript). Register additional extensions through LanguageFileExtensionsMap:

File extension to language mappingPascalC++
with TMSFNCMemo1.LanguageFileExtensionsMap.Add do
begin
  Language  := mlCpp;
  Extension := '.cu';   // CUDA source files
end;
// Convenience overload
TMSFNCMemo1.LanguageFileExtensionsMap.Add(mlPascal, '.dpr');

TTMSFNCMemoLanguageFileExtensionMapItem *item = TMSFNCMemo1->LanguageFileExtensionsMap->Add();
item->Language = mlCpp;
item->Extension = ".cu";   // CUDA source files
// Convenience overload
TMSFNCMemo1->LanguageFileExtensionsMap->Add(mlPascal, ".dpr");

Drag and drop

TTMSFNCMemo supports dragging text and files directly into the editor. Because the editor runs inside a TTMSFNCWebBrowser, file access has some constraints: the filename is only available in the DragDrop event; in all preceding events (DragOver, DragEnter) only the MIME type is available.

Handle OnDragDrop to decide what to do with dropped content:

Drag and dropPascalC++
procedure TForm1.TMSFNCMemo1DragDrop(Sender: TObject; const Data: TDragObject;
  const Point: TPointF);
var
  obj: TTMSFNCMemoDragObject;
begin
  obj := Data.Source as TTMSFNCMemoDragObject;
  if obj.Kind = otText then
    TMSFNCMemo1.Lines.Add(obj.Text)
  else if obj.Files.Count > 0 then
    obj.Files[0].Open;
end;

void __fastcall TForm1::TMSFNCMemo1DragDrop(TObject *Sender, const TDragObject &Data,
  const TPointF &Point)
{
  TTMSFNCMemoDragObject *obj = dynamic_cast<TTMSFNCMemoDragObject*>(Data.Source);
  if (obj->Kind == otText)
    TMSFNCMemo1->Lines->Add(obj->Text);
  else if (obj->Files->Count > 0)
    obj->Files->Items[0]->Open();
}

In VCL, set Allow := False in DragOver to prevent the drop; in FMX, set Operation := TDragOperation.None.

Note

Setting Allow / Operation to prevent a drop does not update the cursor visual in the editor, because cursor rendering is controlled by the embedded browser.

Combining sources, file extension mapping, and drag-and-drop

Register a custom extension, load multiple sources from a folder, and handle dropped files to add them as new sources:

Combining sources, file extension mapping, and drag-and-dropPascalC++
procedure TForm1.FormCreate(Sender: TObject);
begin
  TMSFNCMemo1.LanguageFileExtensionsMap.Add(mlPascal, '.dpr');
  TMSFNCMemo1.AddSourcesFromFolder('C:\Projects\src\');
  TMSFNCMemo1.ActiveSource := 0;
end;

procedure TForm1.TMSFNCMemo1DragDrop(Sender: TObject;
  const Data: TDragObject; const Point: TPointF);
var
  obj: TTMSFNCMemoDragObject;
begin
  obj := Data.Source as TTMSFNCMemoDragObject;
  if (obj.Kind = otFile) and (obj.Files.Count > 0) then
    obj.Files[0].Open;
end;

void __fastcall TForm1::FormCreate(TObject *Sender)
{
  TMSFNCMemo1->LanguageFileExtensionsMap->Add(mlPascal, ".dpr");
  TMSFNCMemo1->AddSourcesFromFolder("C:\\Projects\\src\\");
  TMSFNCMemo1->ActiveSource = 0;
}

void __fastcall TForm1::TMSFNCMemo1DragDrop(TObject *Sender,
  const TDragObject &Data, const TPointF &Point)
{
  TTMSFNCMemoDragObject *obj = dynamic_cast<TTMSFNCMemoDragObject*>(Data.Source);
  if ((obj->Kind == otFile) && (obj->Files->Count > 0))
    obj->Files->Items[0]->Open();
}

See also