DelphiHTMLWriter

March 12, 2026 ยท View on GitHub

A Delphi class library for creating HTML using a fluent interface. Supports HTML 4.01, XHTML, and HTML5.

License

This project is licensed under the Mozilla Public License 2.0.

Overview

THTMLWriter produces HTML through a fluent (method-chaining) interface. It can generate complete HTML documents or standalone HTML fragments. The library enforces correct tag nesting and raises exceptions when tags are used in invalid contexts.

Fluent Interface Pattern

Most methods return IHTMLWriter, allowing calls to be chained:

var
  Doc: IHTMLWriter;
begin
  Doc := HTMLWriterCreateDocument(dtHTML5);
  Doc.OpenHead
        .AddTitle('My Page')
      .CloseTag
      .OpenBody
        .AddHeading1Text('Hello World')
        .AddParagraphText('Welcome to my page.')
        .OpenDiv.AddClass('container')
          .AddBoldText('Important!')
        .CloseTag
      .CloseTag
    .CloseDocument;

  WriteLn(Doc.AsHTML);
end;

Key Concepts

  • Open methods (OpenDiv, OpenTable, etc.) add an opening tag and leave it ready for attributes or content. Each must be paired with a CloseTag call.
  • Add methods (AddBoldText, AddParagraphText, etc.) write a complete open/content/close sequence in one call. No CloseTag needed.
  • Attribute methods (AddAttribute, AddClass, AddStyle, AddID, etc.) attach attributes to the currently open tag.
  • Boolean attribute methods (AddRequired, AddDisabled, AddHidden, etc.) add bare HTML5 boolean attributes.

Supported Standards

StandardSupport
HTML 4.01 (Strict, Transitional, Frameset)Full
XHTML 1.0 / 1.1Full
HTML5Full

HTML5 Features

  • Semantic elements: <article>, <aside>, <details>, <figcaption>, <figure>, <footer>, <header>, <main>, <nav>, <section>, <summary>, <dialog>, <picture>, <template>
  • Text-level semantics: <mark>, <bdi>, <ruby>, <rt>, <rp>, <time>, <output>, <wbr>
  • Media elements: <audio>, <video>, <source>, <track>, <canvas>, <embed>
  • Form elements: <datalist>, <progress>, <meter>, plus all HTML5 input types (color, date, email, range, search, tel, url, week, etc.)
  • Attribute helpers: AddRole, AddDataAttribute, AddAriaAttribute, AddPlaceholder
  • Boolean attributes: AddRequired, AddDisabled, AddAutofocus, AddHidden, AddReadonly, AddMultiple, AddNovalidate
  • Convenience combos: AddFigure (img + figcaption), AddDetailsSummary (summary + details)
  • Deprecation warnings: Tags deprecated in HTML5 (e.g., <center>, <font>, <strike>, <frameset>) raise exceptions when elStrictHTML5 is enabled
  • DOCTYPE: dtHTML5 produces <!DOCTYPE html>

Error Checking

Set ErrorLevels to control validation:

var Writer: IHTMLWriter;
begin
  Writer := HTMLWriterCreateDocument(dtHTML5);
  Writer.ErrorLevels := Writer.ErrorLevels + [elStrictHTML5];
  // Using deprecated tags will now raise ETagIsDeprecatedHTMLWriterException
end;

Creating HTML

// Full document with DOCTYPE
Doc := HTMLWriterCreateDocument(dtHTML5);

// HTML chunk starting from any tag
Chunk := HTMLWriterCreate('div');

// Fragment without a wrapper element
Fragment := HTMLWriterCreateFragment;

Running Tests

The project includes a comprehensive DUnit test suite in the Test/ directory. Open and run TestuHTMLWriter.pas with the Delphi test runner.