Sign in Join

Live chat for Free Pascal, Lazarus, Delphi and every Pascal programmer.

Catalog · How the catalog works
Anything · Lazarus or Delphi
Random projectRandom project

opcb-object-pascal-component-builder

OPCB – Object Pascal Component Builder A library for fluent creation and configuration of components in Delphi and Lazarus. Enables expressive, hierarchical, and reusable runtime UI construction. Developed by Fabiano Arndt. Copyright © 2025 Fabiano Arndt

View on GitHub

Member rating

No ratings yet.

Sign in to rate this project.

README

OPCB – Object Pascal Component Builder

Versão em português: veja README_PT.md

🚀 Instantiate and configure Delphi and Lazarus components in a fluent, expressive, and reusable way — entirely at runtime, with no .dfm/.lfm required.

OPCB (Object Pascal Component Builder) is a library for Delphi and Lazarus that lets you build and configure visual components in code, with a fluent, chainable, and readable API. It targets a case the design-time form designer doesn't cover well: UI whose shape is only known at runtime — driven by data, by a schema, by user choices, or by anything else the designer can't see in advance.

Table of Contents

📖 Documentation

docs

📖 Articles

articles

✨ Benefits

  • 🔹 Fluent API – Configure properties and events in a chained way.
  • 🔹 Less repetitive code.
  • 🔹 Hierarchical organization – Facilitates creation of nested layouts.
  • 🔹 Automatic grid support – Add controls in cells with RowSpan and ColSpan.
  • 🔹 Three builders, one API style – TControlCreator for visual controls, TComponentCreator for non-visual components (dialogs, timers, datasets...), TMenuCreator for menu trees.
  • 🔹 RTTI-based property/event assignment – Set arbitrary properties (WithProp) and events (WithEvent) by name, even on component classes the library doesn't know about ahead of time.
  • 🔹 Compatible with VCL, LCL, and FMX.
  • 🔹 Extensively tested – see Tested below.

🚀 Usage Examples

Simple control creation:

pascal
uses
  OPCB;

procedure TForm1.FormCreate(Sender: TObject);
var
  Creator: TControlCreator;
begin
  Creator := TControlCreator.Create;
  try
    Creator
      .SetOwnerAndParent(Self, Self)
      .SetSpace(5, 5)
      .SetTopLeft(10, 10)
      .SetDirection(cpdVertical)
      .Add(TControlBuilder.Create(TLabel).WithCaption('Nome'))
      .Add(TControlBuilder.Create(TEdit, 'edit_name').WithWidth(250).WithCaption(''))
      .IncTop(15)
      .Add(TControlBuilder.Create(TLabel).WithCaption('Idade'))
      .Add(TControlBuilder.Create(TNumberBox).WithWidth(50))
      .IncTop(20)
      .SetDirection(cpdHorizontal)
      .Add(TControlBuilder.Create(TButton, 'button_enviar').WithCaption('Enviar'))
      .Add(TControlBuilder.Create(TButton, 'button_cancelar').WithCaption('Cancelar'))
      .AlignControlsRight(['button_enviar', 'button_cancelar'], ['edit_name'])
    ;
  finally
    Creator.Free;
  end;
end;

Exemplo 01

Nested control creation:

pascal
uses
  OPCB;

procedure TForm1.FormCreate(Sender: TObject);
var
  Creator: TControlCreator;
begin
  Creator := TControlCreator.Create;
  try
    Creator
      .SetOwnerAndParent(Self, Self)
      .SetTopLeft(10, 10)
      .SetSpace(5, 5)
      .SubLevel(TControlBuilder.Create(TGroupBox).WithCaption('Opções').WithWidthAndHeight(250, 250))
        .SetDirection(cpdVertical)
        .SetTopLeft(20, 20)
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 1'))
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 2'))
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 3'))
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 4'))
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 5'))
        .Add(TControlBuilder.Create(TCheckBox).WithCaption('Opção 6'))
      .SuperLevel
      .SubLevel(TControlBuilder.Create(TPanel).WithWidthAndHeight(250, 250))
        .SetDirection(cpdVertical)
        .SetTopLeft(20, 20)
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 1'))
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 2'))
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 3'))
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 4'))
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 5'))
        .Add(TControlBuilder.Create(TLabel).WithCaption('Informação 6'))
        .IncTop(50)
        .Add(TControlBuilder.Create(TButton).WithCaption('Copiar'))
      .SuperLevel
    ;
  finally
    Creator.Free;
  end;
end;

Exemplo 02

Grid Mode:

pascal
uses
  OPCB;

procedure TForm1.FormCreate(Sender: TObject);
var
  Creator: TControlCreator;
begin
  Creator := TControlCreator.Create;
  try
    Creator
      .SetOwnerAndParent(Self, Self)
      .SetTopLeft(20, 20)
      .SetSpace(5, 5)
      .SetDirection(cpdVertical)
      .GridInit(4, 6)
        .GridSetCellWidthAndHeight(70, 70)
        .GridSetColWidth(0, 200)
        .GridSetRowHeight(1, 150)
        .Add(TControlBuilder.Create(TPanel).WithCaption('1'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('2'))
        .SubLevel(TControlBuilder.Create(TPanel).WithCaption('3'))
          .Add(TControlBuilder.Create(TButton).WithCaption('B1'))
          .Add(TControlBuilder.Create(TButton).WithCaption('B2'))
        .SuperLevel
        .Add(TControlBuilder.Create(TPanel).WithCaption('4'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('5'))
        .SetDirection(cpdHorizontal)
        .GridColSpan(2)
        .GridRowSpan(2)
        .Add(TControlBuilder.Create(TPanel).WithCaption('6'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('7'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('8'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('9'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('10'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('11'))
        .GridSkipCell
        .Add(TControlBuilder.Create(TPanel).WithCaption('12'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('13'))
        .GridRowSpan(2)
        .Add(TControlBuilder.Create(TPanel).WithCaption('14'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('15'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('16'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('17'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('18'))
        .Add(TControlBuilder.Create(TPanel).WithCaption('19'))
      .GridFinish
    ;
  finally
    Creator.Free;
  end;
end;

Exemplo 03

🚀 Example: Building a Virtual Keyboard

The example below demonstrates how to build a complete virtual keyboard using the library.

pascal
procedure TForm1.FormCreate(Sender: TObject);
var
  Creator: TControlCreator;
begin
  Creator := TControlCreator.Create;
  try
    Creator
      .SetOwnerAndParent(Self, Self)
      .SetSpace(2, 2)
      .SetTopLeft(20, 20)
      .SubLevel(TControlBuilder.Create(TPanel))
        .SetTopLeft(10, 10)
        .GridInit(4, 10)
          .GridSetCellWidthAndHeight(80, 80)
          .GridSetRowOffset(1, 22)
          .GridSetRowOffset(2, 65)
          .External(procedure (ACreator: TControlCreator)
            const KeyRows: array[0..1] of string = ('QWERTYUIOPASDFGHJKL', 'ZXCVBNM');
            var Key: Char;
            begin
              for Key in KeyRows[0] do
                ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption(Key));
              ACreator.Break;
              for Key in KeyRows[1] do
                ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption(Key));
              ACreator.Break;
              ACreator.GridSkipCells(2);
              ACreator.GridColSpan(5);
              ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption('[ SPACE ]'));
            end
          )
        .GridFinish
        .IncLeft(20)
        .GridInit(4, 3)
          .GridSetCellWidthAndHeight(80, 80)
          .External(procedure(ACreator: TControlCreator)
            const Keys = '789456123';
            var Key: Char;
            begin
              for Key in Keys do
                ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption(Key));
              ACreator.GridColSpan(2);
              ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption('0'));
              ACreator.Add(TControlBuilder.Create(TSpeedButton).WithCaption(','));
            end
          )
        .GridFinish
        .RecalcParentSize(10, 10)
      .SuperLevel
    ;
  finally
    Creator.Free;
  end;
end;

Exemplo 04

🔑 Features Demonstrated

  • Fluent control creation
    • .SetOwnerAndParent(Self, Self) defines owner and parent.
    • .SetSpace(2, 2) / .SetTopLeft(20, 20) control spacing and initial position.
  • Hierarchy of levels
    • .SubLevel(...) opens a new construction scope (e.g. a TPanel).
    • .SuperLevel returns to the previous level.
  • Grid layouts
    • .GridInit(Rows, Cols) starts a grid.
    • .GridSetCellWidthAndHeight(W, H) defines the cell dimensions.
    • .GridSetRowOffset(Row, Offset) applies offset in specific rows.
  • Dynamic control insertion
    • .External(procedure(ACreator: TControlCreator) ...) allows batch creation of controls such as keys from arrays/strings.
  • Grid positioning control
    • .Break → line/column break (direction-dependent — see docs before relying on it for a plain "next line down"; .BreakLine/.BreakColumn are the unconditional versions).
    • .GridSkipCells(N) → skips cells.
    • .GridColSpan(N) → merges columns (e.g. SPACE key).
  • Automatic container adjustment
    • .RecalcParentSize(PaddingX, PaddingY) automatically resizes the parent container.

🎹 Result

The example creates:

  • A QWERTY keyboard with two letter rows and an expanded [ SPACE ] key.
  • A numeric keyboard with digits 0–9 and a comma.
  • Both organized within a TPanel that automatically adjusts to its content.

🧪 Examples Gallery

Beyond the snippets above, the examples/Builders folder has full, runnable projects — one subfolder per platform (Lazarus, VCL, FMX, plus a couple of cross-compiler VCL-Lazarus ones). Each is a standalone Delphi/Lazarus project you can open and run directly.

Platform Example What it demonstrates
Lazarus schema-driven-ui A single generator renders a data-driven field schema as either a 2-column grid or a 1-column stack, and reads values back by field name — UI whose shape only exists at runtime.
Lazarus book-search Open Library book-search screen with query box, pagination, progress bar, and dynamically generated book cards.
Lazarus sqlite SQLite-backed app: login screen, main menu/status bar, and a dynamically opened tabbed Users CRUD form.
Lazarus virtual-keyboard On-screen virtual keyboard (QWERTY + numeric keypad) built from custom-styled speed buttons in a grid.
Lazarus grid-mode Grid layout mode with column/row spans and skipped cells, arranging 18 panels/buttons irregularly.
Lazarus dialogs Modal builder-dialogs: state list, masked phone, color picker, spin edit, string grid, trackbar, dual-listbox mover, and a searchable in-memory-dataset DB grid.
Lazarus exemplo-menus Main menu and popup menu tree (File/Edit/Search) built via TMenuCreator.
Lazarus custom-helper-for-builders How to write your own class helper methods (e.g. WithFontSize, WithVisible) for the library's builder classes.
VCL exemplo-populator-tela-login Full login screen (fields, checkbox, button, footer) built and aligned entirely via the builder.
VCL virtual-keyboard On-screen virtual keyboard (QWERTY + numeric keypad) with nested grids, row offsets and spans.
VCL dialogs Modal builder-dialogs: masked phone, color picker, calendar view, string grid, trackbar, dual-listbox mover, and a searchable ClientDataSet DB grid.
VCL grid-autoexpand Grid layout mode (GridInit/GridFinish) with a minimal 2×2 example.
VCL exemplo-menu Main menu and popup menu tree (File/Edit/Search) built via TMenuCreator.
VCL exemplo-panelflow-card Adds avatar profile cards (image + name/contact labels) to a flow panel on demand, one click at a time.
VCL exemplo-classes-personalizadas Building your own custom control class (a self-clicking button) with the builder, alongside regular controls.
VCL custom-helper-for-builders How to write your own class helper methods for the library's builder classes.
VCL no-dfm / no-dfm-2 Minimal forms built with no .dfm file at all — every control created in code.
VCL-Lazarus no-dfm The same no-.dfm/.lfm idea, written once and compiled unmodified under both Delphi and Lazarus.
FMX dialogs Modal builder-dialogs: password entry, a string-grid date picker, a trackbar picker, a state picker, and a dual-listbox mover.
FMX exemplo-menu Main menu and popup menu tree (File/Edit/Search) built via TMenuCreator.
FMX flow-card Adds avatar profile cards to a flow layout on demand, one click at a time.
FMX CRUD1 Minimal TOPCBCreators layout demo (a small starting point, not a full CRUD screen despite the name).

✅ Tested

OPCB ships with an extensive automated regression suite, run on every change against both compilers this library supports — because the two catch different classes of bugs (the Delphi/DUnitX suite, for instance, is the only one that reliably surfaces memory leaks via FastMM):

🧩 Requirements

  • Delphi: a version with generics and interface support (10.x or newer recommended). Targets VCL and FMX.
  • Lazarus / Free Pascal: FPC 3.2+ (the library relies on generics and advanced records). Targets the LCL.

🧩 Installation

🔹 Option 1 – Clone the repository

bash
git clone https://github.com/fabianoallex/opcb-object-pascal-component-builder.git

🔹 Option 2 – Manual download

Download the ZIP file from the GitHub repository and extract it to a folder of your choice.

💠 Delphi

  1. Open Delphi.
  2. Go to Tools ▸ Options ▸ Language ▸ Delphi Options ▸ Library.
  3. In the Library Path field, add the full path to the src folder. Example: C:\opcb\src

💠 Lazarus

  1. Open Lazarus.
  2. Go to Project ▸ Project Options ▸ Compiler Options ▸ Paths.
  3. In Other unit files (-Fu), add the path to the src folder. Example: C:\opcb\src

🧰 Done!

After that, the project's units will be available for use in your Delphi or Lazarus projects.

📄 License

OPCB is licensed under the Apache License, Version 2.0 — see LICENSE and NOTICE for the full text and attribution details.