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Glossary

A reference guide to PDF and PDFDancer terminology.

A​

AcroForm​

The standard PDF form technology for interactive form fields. AcroForms support text fields, checkboxes, radio buttons, dropdowns, and buttons. PDFDancer can select, fill, and modify AcroForm fields programmatically.

See also: Working with AcroForms

Aspect Ratio​

The proportional relationship between an image's width and height, expressed as width divided by height. For example, a 200×100 image has an aspect ratio of 2.0. When scaling images, you can choose to preserve or ignore the aspect ratio.

See also: Scaling Images

B​

Bounding Rectangle (Bounding Rect)​

A rectangle that defines the position and size of a PDF element. Contains four values: x (left edge), y (bottom edge), width, and height, all measured in points from the page origin.

Builder Pattern​

A design pattern used throughout PDFDancer for creating and editing content. Builders allow chaining method calls for readable, declarative code (e.g., pdf.new_paragraph().text("Hello").font("Helvetica", 12).add()).

See also: Fluent Builders

C​

Coordinate System​

PDF uses a Cartesian coordinate system with the origin (0, 0) at the bottom-left corner of the page. The X-axis increases from left to right, and the Y-axis increases from bottom to top. All measurements are in points.

See also: PDF Coordinate System

E​

Embedded Font​

A font file that is included within the PDF document itself, ensuring consistent text rendering across all PDF viewers regardless of which fonts are installed on the viewing system. PDFDancer supports embedding TrueType (.ttf) fonts.

F​

Fluent API​

A programming interface design that allows method chaining, where each method returns an object that can receive further method calls. PDFDancer uses fluent APIs for building paragraphs, images, and edits.

FormXObject​

A reusable content stream in PDF that can be referenced multiple times throughout a document. Commonly used for logos, headers, footers, and watermarks. FormXObjects reduce file size by storing content once and referencing it multiple times.

See also: Working with FormXObjects

G​

Glyph​

The visual representation of a character in a font. Each character (like "A" or "!") has a corresponding glyph that defines how it appears when rendered.

I​

Image​

A raster graphic (PNG, JPEG, etc.) embedded in a PDF. PDFDancer can select, add, replace, delete, and transform images. Transformations include scaling, rotating, cropping, adjusting opacity, and flipping.

See also: Working with Images

Image Transformation​

Operations that modify an existing image in-place within a PDF. Supported transformations include:

  • Scale: Resize by factor or to specific dimensions
  • Rotate: Rotate by angle in degrees
  • Crop: Trim pixels from edges
  • Opacity: Adjust transparency (0.0 to 1.0)
  • Flip: Mirror horizontally, vertically, or both
  • Replace: Swap image content while keeping position

See also: Transforming Images

O​

Opacity​

The transparency level of an element, expressed as a value from 0.0 (fully transparent) to 1.0 (fully opaque). PDFDancer supports setting opacity on images to create watermark effects or visual layering.

See also: Setting Image Opacity

P​

Page​

The fundamental container in a PDF document. Each page has dimensions (width and height in points), a page number, and contains content such as paragraphs, images, paths, and form fields.

See also: Working with Pages

Paragraph​

PDFDancer's high-level text abstraction representing a logical block of text that may span multiple lines. Paragraphs are the primary way to work with text content in PDFDancer.

See also: Paragraphs

Path​

A vector graphics element consisting of lines, curves, and shapes. Paths can have strokes (outlines) and fills (interior colors). Used for drawings, borders, decorative elements, and diagrams.

See also: Working with Vector Graphics

PDF Point​

The base unit of measurement in PDF documents. One point equals 1/72 of an inch. Common conversions:

  • 72 points = 1 inch
  • 1 inch margin = 72 points
  • A4 page = 595 × 842 points

Position​

An object that encapsulates coordinate information for element placement and selection. Positions include page number, coordinates (x, y), and optionally a bounding rectangle and selection mode.

Position Mode​

Determines how elements are matched when selecting by position:

  • INTERSECT: Select elements that overlap with the position area
  • CONTAIN: Select elements fully contained within the position area
  • EXACT: Select elements at exact coordinates

R​

Reflow Preset​

Controls how text is adjusted when replacement text is longer or shorter than the original. Options include:

  • BEST_EFFORT: Automatically adjusts text to fit available space (recommended)
  • FIT_OR_FAIL: Fails if text doesn't fit in the available space
  • NONE: No reflow; text may overflow or be truncated

See also: Working with Templates

Redaction​

The process of permanently removing sensitive content from a PDF. Unlike simply covering content with a black box, true redaction removes the underlying data from the document.

See also: Redaction

RGB Color​

The color model used in PDFDancer, where colors are specified by red, green, and blue components, each ranging from 0 to 255 (e.g., Color(255, 0, 0) for red).

S​

Session​

A PDFDancer session represents an active connection for working with a PDF document. Sessions maintain state and must be used from a single thread. Create a new session for each PDF you want to process.

Snapshot​

A saved state of a PDF document that can be restored later. Useful for implementing undo functionality or trying different modifications.

See also: Working with Snapshots

Standard Fonts​

The 14 fonts guaranteed to be available in all PDF readers without embedding:

  • Serif: Times-Roman, Times-Bold, Times-Italic, Times-BoldItalic
  • Sans-serif: Helvetica, Helvetica-Bold, Helvetica-Oblique, Helvetica-BoldOblique
  • Monospace: Courier, Courier-Bold, Courier-Oblique, Courier-BoldOblique
  • Symbol: Symbol, ZapfDingbats

See also: Standard PDF Fonts, Available Fonts

Stroke​

The outline of a path or shape, defined by color and line width. Compare with Fill, which is the interior color.

T​

Templates​

PDF documents with placeholder text (e.g., {{NAME}}, {{DATE}}) that can be filled with dynamic content. PDFDancer supports filling templates for mail merge operations, invoice generation, certificate creation, and personalized document generation. All SDKs provide both simple syntax and fluent APIs for template replacement, with support for custom fonts and colors. Supports text reflow options to handle varying replacement text lengths.

See also: Working with Templates

TextLine​

An individual line of text within a paragraph. TextLines provide finer-grained control than paragraphs for line-by-line text manipulation.

See also: TextLines

TrueType Font (TTF)​

A font format that can be embedded in PDF documents. PDFDancer supports embedding custom TrueType fonts for precise typography control.

V​

Vector Graphics​

Graphics defined by mathematical equations (points, lines, curves) rather than pixels. Vector graphics scale without loss of quality. In PDF, vector graphics are represented as paths.

See also: Working with Vector Graphics

X​

XObject​

See FormXObject.