TMS FNC Blox Selector — Guides

TTMSFNCBloxSelector is a categorized palette of the blocks and lines available to a TTMSFNCBloxControl. It lists every registered element as an item, and the user drags an item onto the diagram canvas to insert an element of that type. Use it alongside (or instead of) the ToolBar when you want a visible catalog of shapes users can drag from. This guide covers linking, controlling which elements appear, appearance, and custom item drawing.

Linking to a Blox Control

Assign BloxControl to the target control. When linked, the selector populates itself from that control's registered elements, and dragging an item onto the canvas inserts an element of that type at the drop position.

procedure TForm1.FormCreate(Sender: TObject);
begin
  BloxSelector1.BloxControl := BloxControl1;
end;

Controlling the palette

The selector reflects the elements registered with the blox control (see Custom elements). Shape the palette with Modes (show blocks, lines, or both), Columns / Rows (grid layout), and Rebuild to refresh after changes. Each entry is a TTMSFNCBloxSelectorItem you can fine-tune through the Items collection — its Text, Hint, Visible, and Enabled.

procedure TForm1.ConfigurePalette;
begin
  BloxSelector1.Modes := [bsmBlocks];   { blocks only; use [bsmBlocks, bsmLines] for both }
  BloxSelector1.Columns := 3;
  BloxSelector1.Rebuild;                { refresh after changing modes }

  { Fine-tune an individual entry. }
  if BloxSelector1.Items.Count > 0 then
  begin
    BloxSelector1.Items[0].Hint := 'Drag onto the canvas to insert';
    BloxSelector1.Items[0].Visible := True;
  end;
end;

Note

Modes is a set — [bsmBlocks, bsmLines] shows both (the default). An item's RegistrationElement (the element class it inserts) is assigned by the registration system and is read-only.

Appearance

Appearance (TTMSFNCBloxSelectorAppearance) styles items in every state. Set Fill / Stroke for the normal state and the Hover, Down, Selected, and Disabled variants, plus Font, ItemWidth / ItemHeight, and spacing. This example themes the palette and limits it to blocks in a three-column grid — combining appearance, modes, and layout:

procedure TForm1.ThemeSelector;
begin
  BloxSelector1.BeginUpdate;
  try
    BloxSelector1.Modes := [bsmBlocks];
    BloxSelector1.Columns := 3;

    BloxSelector1.Appearance.Fill.Color := MakeGraphicsColor(250, 250, 252);
    BloxSelector1.Appearance.FillSelected.Color := MakeGraphicsColor(74, 144, 217);
    BloxSelector1.Appearance.FillHover.Color := MakeGraphicsColor(232, 240, 254);
    BloxSelector1.Appearance.Font.Name := 'Segoe UI';
    BloxSelector1.Appearance.ItemWidth := 96;
    BloxSelector1.Appearance.ItemHeight := 72;
  finally
    BloxSelector1.EndUpdate;
  end;
  BloxSelector1.Rebuild;
end;

A Blox Selector palette showing categorized block and line items

Custom item drawing

For per-item visuals beyond the appearance settings — a badge, a status tint, a custom glyph — handle OnItemBeforeDrawContent. You receive the item's graphics surface and rectangle; draw what you need and set ADefaultDraw := False to replace the default content:

procedure TForm1.BloxSelector1ItemBeforeDrawContent(Sender: TObject;
  AGraphics: TTMSFNCGraphics; ARect: TRectF; AItemIndex: Integer;
  var ADefaultDraw: Boolean);
begin
  { Draw a tinted badge over the top-left of every fifth item. }
  if AItemIndex mod 5 = 0 then
  begin
    AGraphics.Fill.Color := MakeGraphicsColor(246, 140, 30);
    AGraphics.DrawRectangle(RectF(ARect.Left, ARect.Top, ARect.Left + 14, ARect.Top + 14));
  end;
  { Leave ADefaultDraw True to keep the default item content as well. }
end;

Pitfalls

The palette is empty until elements are registered on the linked control. Register custom blocks (or rely on the built-in libraries) before expecting items to appear.
Call Rebuild after changing Modes or registrations at runtime — the selector does not always refresh on its own.
RegistrationElement is read-only. To add a new palette entry, register a new element, don't try to construct an item manually.

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