Native PDF generation, editing, signing, standards-aware output, font optimization, and imaging for RAD Studio applications.

Project Overview

HotPDF is a source-level PDF component library for Delphi and C++Builder. It is built for desktop software that needs deterministic PDF output, direct page drawing, strong RAD Studio integration, and compact deployment.

The component covers everyday PDF generation, advanced document assembly, PDF editing, image-heavy output, forms with duplicate field-name guards, annotations, creation-time AcroForm field wrappers, reusable action-builder chains for open actions, document lifecycle actions, page additional actions, annotation actions, annotation additional actions, AcroForm additional actions, encryption, signing workflows, font optimization, and stream-based workflows from a single native API surface

The loaded-document toolkit adds page-range deletion, outline-aware and AcroForm-aware merging, multi-widget form constraint, geometry, visibility, rotation, border, and colour editing, complete annotation editing, automatic activation of bare web and email addresses, stateless next-match search, complete typed outline snapshots, Windows certificate-store signing, deterministic collated printing with paper capability discovery, full-page, bounded-region, and pixel-bounded Viewer snapshots, cache-aware adjacent-page prefetch, persistent page highlights, rotation-aware marquee selection, current-view printing, keyboard and wheel navigation, and VCL viewer components

Recent library releases expanded HotPDF from a classic PDF writer into a broader native PDF toolkit covering version-specific PDF 1.3 / 1.4 / 1.5 / 1.6 / 1.7 feature gating, native PDF 2.0 output, PDF/A-1 / -2 / -3 / -4 + PDF/X-1a / -3 / -4 + PDF/UA-1 / -2 standards conformance, PAdES baseline / extended / long-term-validation digital signatures, an in-process PFX / PKCS#12 signing pipeline that does not depend on OpenSSL or external native binaries, incremental update saving with stable permanent IDs, rotating modification IDs, and byte-exact no-op saves, CFF / OpenType / CID-keyed CFF font subsetting, and PDF export adapters for FastReport, QuickReport, ReportBuilder, and DevExpress ExpressPrinting that route their existing reports through HotPDF as a single PDF backend. A Direct File API processes multi-gigabyte, million-object PDFs file-to-file - page counts, copies, document-information rewrites, and AES-256 encryption or decryption - in seconds, while the bounded recovery loader can relocate a valid xref section or rebuild direct-object offsets after damaged startxref and xref data without trusting nested object-like text or binary data

The opt-in LinearizeOutput writer adds fast web view output with a first-page dependency section, shared-object grouping, primary page and shared-object hint tables, and an early compatibility cross-reference table while retaining direct file and stream destinations

Loaded stream filters run through a reusable pipeline whose final stage writes directly to caller-owned streams and whose intermediate stages spill from memory to temporary files, with strict ASCII85 and ASCIIHex end markers, independent per-chain and document-wide decoded-byte ceilings, filter-count and pipeline-depth limits, indirect-reference cycle detection, same-stream recursion rejection, and structured diagnostics for every success or failure

Predictor encoding now exposes strict reusable TIFF and fixed or adaptive PNG paths for packed, 8-bit, and 16-bit rasters; loaded images can copy native or generically decoded payloads directly to caller streams, while selective optimization uses memory-to-disk spill buffers, deterministic four-strategy high-ratio Flate selection, and bounded parallel image jobs that commit only smaller payloads in source order

Large loaded streams remain source-file windows until mutation and can expose independent read-only source slices without copying; after mutation they use the configurable LoadedStreamMemoryThreshold to select memory or an owned temporary file; object-stream members are indexed by object number and parsed only when referenced, while LoadFromRandomAccessSource connects HTTP range readers and custom storage and progressive linearization probes identify the exact first-page and main-xref ranges needed before a complete download

Revision-aware loading now validates xref free lists and generation transitions while retaining bounded details for duplicate and shadowed object definitions; explicit clean, dirty, released, and must-write object states support low-memory post-save object-stream cache release, while deterministic dictionary order and QDF-style diagnostic output make structural inspection reproducible

Reusable layout elements support side-effect-free measurement, verified split heads, and owned overflow continuations for paragraphs, rows, containers, and custom content; declarative page callbacks compose backgrounds, headers, document content, footers, and foregrounds in stable order, while unbounded reports retain file-backed page staging, paragraph constraints, bounded diagnostics, semantic helpers, and bidi direction control

Loaded-page rendering executes coloured and uncoloured tiling patterns plus axial and radial shading patterns for fills and strokes, honours pattern matrices and path clipping, and bounds recursive pattern depth and tile execution for hostile resources

SanitiseLoadedDocument applies JavaScript-only, active-content, or strict untrusted-document policies to loaded PDFs, removes unreachable payload objects, compacts live object numbers, and safely rewrites in place through atomic file replacement

Preflight JSON, HTML, and veraPDF-style findings expose stable namespaced rule identifiers and structured PDF locations with logical scope, path, key, and exact object, page, or byte coordinates when available, while text and CSV compatibility remains unchanged

Reusable validation policies now combine structural preflight with strict or WTPDF intake requirements, extract canonical declaration and claim metadata, run ordered file batches through bounded worker and queue limits, preserve source-aware errors, and offer inspect, add-missing, and synchronize modes for XMP repair independently of structural PDF repair

Factur-X and ZUGFeRD intake now cross-checks the primary invoice attachment MIME type and FileSpec names against the EmbeddedFiles and Catalog AF registrations, exposes the decoded MIME type and XMP namespace URI, and rejects mismatched XMP document types or extension namespaces

PDF 2.0 output now supports PDF/A-4, PDF/A-4e, PDF/A-4f, and PDF/UA-2 identification, including revision-aware XMP, namespace-aware structure elements, strict namespace registration checks, PDF 2.0 structure roles, and associated-file authoring for the archival engineering and file-embedding profiles

The v2.119.32-51 cycle added producer-side Arabic / Persian / Urdu shaping (LAM-ALEF mandatory ligature, Arabic Presentation Forms-A 9 letters), a feature-complete OpenType GSUB substitution engine covering every LookupType 1-8 with Script / LangSys selection and TTF subsetter closure for substitute glyphs, XFA (XML Forms Architecture) container support (AddXFAPacket / ClearXFAPackets / XFAPacketCount), an AcroForm /AA /K + /F + /V + /C form-field trigger family, multi-Unicode /DR font registration via RegisterAcroFormFont, structure-element accessibility attribute setters (/Lang / /E / /T) with a Table 333 standard structure type enum and AddStructureElement typed overload, and marked-content sequence properties on BeginTaggedContent.

The v2.119.52-68 cycle closed the Phase 8 automatic shaping pipeline and broadened script coverage: Arabic Extended-A (including the U+0750-077F Arabic Supplement and U+08A0-08FF Arabic Extended-A) and Persian / Urdu Form-B were extended into the full U+0672-06D5 joining-class table plus 26 new Forms-A mappings, with post-pass folding for LAM-ALEF, YEH-HAMZA + vowel pairs (8 ligatures in U+FBEA-FBFB), the standalone Allah ligature (U+FDF2), and the 22-codepoint Bismillah phrase (U+FDFD). The new opt-in ShapingFeatures property + THPDFShapingFeature enum (sfArabicGSUB / sfStandardLigatures / sfContextualLigatures / sfContextualAlternates / sfIndicShaping) makes the producer emit GSUB-driven font-specific rlig / liga / clig / rclt substitutions automatically, with Latin Standard Ligatures (ff / fi / fl / ffi / ffl / ſt / st via U+FB00-FB06) and Devanagari Indic syllable reordering (Repha + pre-base I-matra) joining the same pipeline. New shaping capability methods for Syriac (GetSyriacJoiningClass / GetSyriacPosition), Mongolian (GetMongolianJoiningClass / GetMongolianPosition), and Devanagari (GetDevanagariCategory / ApplyDevanagariReorder) let callers drive non-Arabic complex scripts through the same GSUB engine. GetCodepointAdvance exposes the cached /W em-fraction for wrap calculations, and AssignSyntheticCodepointForGID / GetSyntheticCodepointForGID let producer emit any GSUB substitute GID (Devanagari cluster shapes, stylistic alternates, CJK variation sequences) through Private-Use-Area codepoints with full /CIDToGIDMap + /ToUnicode + /W integration. Cumulative ToUnicode CMap now ships 35 ligature reverse-mapping entries (8 LAM-ALEF + 18 YEH-HAMZA family + 1 Allah + 1 Bismillah + 7 Latin) so consumer-reader copy / paste produces the source codepoints. Documentation skeletons for ChangeLog now ship in 11 languages (EN / CN / AR / DE / ES / FR / IT / JA / KO / PT / RU) with a language-picker UI; ChangeLog retention limit was raised from 250 to 500 version sections.

The v2.152-v2.190 cycle built out a complete OpenType GPOS positioning engine and broadened complex-script coverage. Opt-in shaping options now apply the font's own kerning (pair, contextual, and right-to-left), combining-mark placement (mark-to-base, mark-to-mark, and per-component mark-to-ligature), cursive connection anchors, and vertical kerning for vertical text, all written as standard PDF text operators so any reader renders the same result. Producer-side shaping now covers Arabic (including the Supplement, Extended-A, and Extended-B blocks), Syriac, Mongolian, N'Ko, Adlam, Hanifi Rohingya, Tibetan consonant stacking, Devanagari and the other Indic scripts through the font's Indic feature chain, Javanese, Thai and Lao mark ordering, Hebrew vowel-point ordering, Khmer, Myanmar, Tai Viet, and Meetei Mayek. A family of optional OpenType typography features - standard, discretionary, and historical ligatures, small capitals, oldstyle / lining / proportional / tabular figures, superscripts, subscripts, ordinals, fractions, scientific inferiors, numerators, denominators, stylistic and contextual alternates, localized forms, case-sensitive forms, slashed zero, and vertical alternates - can be applied automatically during text output. Copy, paste, and text search recover the original characters across all shaped output, including ligatures and chained feature substitutions. Font output also became smaller: embedded font programs are always Flate-compressed, a font used on several pages is embedded once per document, subset tags are derived deterministically for reproducible output, and an optional compact mode writes plain-ASCII text with standard fonts as unembedded WinAnsi text.

PDF Standards Coverage

Why Choose HotPDF

Competitive Strengths

The capabilities below are hard technical differentiators for HotPDF versus typical Delphi PDF components. Most competing commercial components either lack these features entirely or are materially weaker in production. Each row maps to a verifiable implementation and a public API surface inside the library.

Recent Library Highlights

Advanced PDF Feature Coverage

High-Performance Compression and Imaging Stack

Quick Delphi Example

program HelloHotPDF;

uses
  System.SysUtils,
  HPDFDoc;

var
  PDF: THotPDF;
begin
  PDF := THotPDF.Create(nil);
  try
    PDF.AutoLaunch := False;
    PDF.FileName := 'HelloHotPDF.pdf';
    PDF.Compression := cmFlateDecode;
    PDF.EnableFontSubsetting := True;
    PDF.BeginDoc;
    PDF.CurrentPage.SetFont('Arial', [], 18);
    PDF.CurrentPage.TextOut(50, 50, 0, 'Hello HotPDF');
    PDF.EndDoc;
  finally
    PDF.Free;
  end;
end.

Package Contents

• Lib: HotPDF source units, package projects, static object files, and bundled third-party library integration.
• Demo\Delphi: Delphi examples for document generation, drawing, images, page setup, encryption, merge/edit workflows, and more.
• Demo\C++Builder: C++Builder examples aligned with the main Delphi demo workflows.
• HtmlHelp: product help and developer reference content.

Typical Use Cases

• Business reports, invoices, statements, and printable records generated from VCL applications.
• Engineering, imaging, and technical-documentation workflows that require direct PDF control.
• Applications that need encrypted, permission-controlled, certificate-recipient, or digitally signed PDF output.
• PDF copy, merge, stamp, edit, and page assembly workflows.
• CJK and multilingual PDF generation where large TrueType or OpenType-CFF fonts must be embedded efficiently.
• Interactive PDF forms, annotation review workflows, presentation PDFs, and document packages with reliable reader compatibility.
• Desktop products that need repeatable PDF generation without installing an external PDF engine.