Table of Contents

Elements and libraries

Everything on a blox canvas is an element. Understanding the element model — and the ready-made libraries Blox ships — is the foundation for everything else in this guide. This chapter explains the class hierarchy, how the Blox collection owns elements, how to add and remove them in code, and which built-in blocks and lines you can drop into a diagram without writing a custom class.

The element model

All diagram objects descend from TTMSFNCBloxElement. Two families branch off it:

  • Blocks — TTMSFNCBloxBlock and its descendants: rectangles, ellipses, diamonds, text blocks, image blocks, groups, and the whole shape library.
  • Lines — TTMSFNCBloxLine and its descendants: straight connectors, arcs, bezier curves, side-lines, and polylines.
TTMSFNCBloxElement
├── TTMSFNCBloxBlock      (rectangles, shapes, text, images, groups, …)
└── TTMSFNCBloxLine       (straight, arc, bezier, side-line, …)

A block carries geometry, a shape, text, and appearance; a line carries a path, arrows, and two endpoints that anchor to block link points. Blocks are covered in Working with blocks; lines in Lines and linking.

The Blox collection

TTMSFNCBloxControl.Blox (type TTMSFNCBloxXBlox) is the document that owns the diagram. You add a created element with Add, and the control takes ownership, paints it, and includes it in hit-testing:

procedure TForm1.BuildButtonClick(Sender: TObject);
var
  LBlock: TTMSFNCBloxBlock;
  I: Integer;
begin
  BloxControl1.BeginUpdate;
  try
    for I := 0 to 2 do
    begin
      LBlock := TTMSFNCBloxBlock.Create;
      LBlock.Left := 40 + I * 180;
      LBlock.Top := 40;
      LBlock.Width := 140;
      LBlock.Height := 70;
      LBlock.Text := 'Block ' + I.ToString;
      BloxControl1.Blox.Add(LBlock);
    end;
  finally
    BloxControl1.EndUpdate;
  end;

  { Remove the first block (this frees it); use Extract to detach without freeing. }
  if BloxControl1.Blox.BlockCount > 0 then
    BloxControl1.Blox.Remove(BloxControl1.Blox.Blocks[0]);
end;

procedure TForm1.ClearButtonClick(Sender: TObject);
begin
  BloxControl1.Blox.Clear;
end;

The collection also exposes typed, read-only views and lookups:

Member Purpose
Elements[i] / ElementCount All elements, in z-order.
Blocks[i] / BlockCount Only blocks.
Links[i] / LinkCount Only lines.
FindElement(AId) Look up an element by its registered Id.
LinkBetweenBlocks(b1, b2) Returns the existing line connecting two blocks, or nil.
Remove / Extract / Clear Delete one element, detach without freeing, or empty the diagram.
Note

LinkBetweenBlocks finds an existing connector; it does not create one. To create a connection, add a TTMSFNCBloxLine and anchor its endpoints — see Lines and linking.

Tip

Wrap bulk changes in BloxControl1.BeginUpdate / EndUpdate so the canvas repaints once instead of after every Add.

Built-in libraries

Beyond the basic blocks and lines, Blox registers several ready-to-use shape libraries. They appear automatically in the Selector and ToolBar, and you can also instantiate them directly:

Library Example classes
Basic TTMSFNCBloxBlock, TTMSFNCBloxTextBlock, TTMSFNCBloxImageBlock, TTMSFNCBloxTriangleBlock, TTMSFNCBloxLinkableBlock, TTMSFNCBloxLine, TTMSFNCBloxArc, TTMSFNCBloxBezier, TTMSFNCBloxSideLine
Flowchart TTMSFNCBloxFlowActionBlock, TTMSFNCBloxFlowDecisionBlock, TTMSFNCBloxFlowTerminalBlock, TTMSFNCBloxFlowDataBlock, TTMSFNCBloxFlowDocumentBlock, …
Electric TTMSFNCBloxResistorBlock, TTMSFNCBloxCapacitorBlock, TTMSFNCBloxDiodeBlock, TTMSFNCBloxGroundBlock, …
Arrow TTMSFNCBloxStandardArrowBlock, TTMSFNCBloxDoubleArrowBlock, TTMSFNCBloxChevronArrowBlock, TTMSFNCBloxQuadArrowBlock, …
DFD TTMSFNCBloxDFDProcessBlock, TTMSFNCBloxDFDDataStoreBlock, TTMSFNCBloxDFDInterfaceBlock, TTMSFNCBloxDFDDataFlowLine
UML TTMSFNCBloxUMLClassBlock, TTMSFNCBloxUMLActorBlock, TTMSFNCBloxUMLUseCaseBlock, TTMSFNCBloxUMLNoteBlock, TTMSFNCBloxUMLGenericLine, …

These library blocks already define their shape and link points, so they are the quickest way to build a real diagram.

Putting it together

The example below assembles a small flowchart from flow blocks and connects them — combining element creation, library blocks, the Blox collection, and linking in one pass:

procedure TForm1.BuildFlowDiagram;
var
  LStart, LAction, LDecision: TTMSFNCBloxBlock;

  function MakeFlowBlock(ABlockClass: TTMSFNCBloxElementClass;
    AText: string; ALeft, ATop: Double; AColor: TTMSFNCGraphicsColor): TTMSFNCBloxBlock;
  begin
    Result := ABlockClass.Create as TTMSFNCBloxBlock;
    Result.Left := ALeft;
    Result.Top := ATop;
    Result.Width := Result.Width + 30;
    Result.Height := Result.Height + 10;
    Result.Text := AText;
    Result.FillColor := AColor;
    Result.StrokeColor := AColor;
    Result.TextColor := gcWhite;
    Result.FontStyle := [xsBold];
    BloxControl1.Blox.Add(Result);
  end;

  procedure Connect(ASource, ATarget: TTMSFNCBloxBlock; ASourcePt, ATargetPt: Integer);
  var
    LLine: TTMSFNCBloxLine;
  begin
    LLine := TTMSFNCBloxDFDDataFlowLine.Create;
    LLine.StrokeColor := MakeGraphicsColor(120, 120, 120);
    LLine.StrokeWidth := 2;
    LLine.SourceLinkPoint.AnchorLink := ASource.LinkPoints[ASourcePt];
    LLine.TargetLinkPoint.AnchorLink := ATarget.LinkPoints[ATargetPt];
    BloxControl1.Blox.Add(LLine);
  end;

begin
  BloxControl1.BeginUpdate;
  try
    BloxControl1.Blox.Clear;
    LStart := MakeFlowBlock(TTMSFNCBloxFlowTerminalBlock, 'Start', 60, 30,
      MakeGraphicsColor(33, 183, 131));
    LAction := MakeFlowBlock(TTMSFNCBloxFlowActionBlock, 'Process order', 50, 170,
      MakeGraphicsColor(23, 110, 168));
    LDecision := MakeFlowBlock(TTMSFNCBloxFlowDecisionBlock, 'In stock?', 50, 320,
      MakeGraphicsColor(246, 140, 30));
    Connect(LStart, LAction, 1, 0);    { Start bottom -> Action top }
    Connect(LAction, LDecision, 1, 0); { Action bottom -> Decision top }
  finally
    BloxControl1.EndUpdate;
  end;
end;
A flowchart built from flow blocks connected with data-flow lines A flowchart built from flow blocks connected with data-flow lines

Pitfalls

  • An element must be added before it is visible. Creating a block does nothing until Blox.Add hands it to the control.
  • Do not free an element you added. The control owns added elements; remove them with Blox.Remove (frees) or Blox.Extract (detaches without freeing).
  • LinkBetweenBlocks returns nil when no connector exists — guard the result before using it.

See also