mirror of https://pdfium.googlesource.com/pdfium synced 2026-07-31 04:29:37 +08:00

History

Tom Sepez e2ae6fb055 Use templating and Zip() in ConvertBuffer_Rgb2Gray()

Replace UNSAFE_TODO() raw pointer loops with compile-time fixed
stride loops using GetScanlineAs<>() and fxcrt::Zip() by templating
for 24 or 32 BPP and updating caller.

TAG=agy
CONV=79149323-9e55-44bc-a43a-b9aedc44a81b

Change-Id: I0e92603cd6a082de393988130a6b00dabcb3be8b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/153410
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

2026-07-28 15:31:43 -07:00

fdrm

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fpdfapi

Improve memory and type safety in CPDF_DIB::GetScanline()

2026-07-27 15:36:56 -07:00

fpdfdoc

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fpdftext

Fix mixed-direction line extraction

2026-07-24 12:08:09 -07:00

fxcodec

Virtualize DecodeImage in ProgressiveDecoderContext

2026-07-28 15:05:42 -07:00

fxcrt

Give CFX_BidiString a way to turn off auto-ordering

2026-07-24 09:18:29 -07:00

fxge

Use templating and Zip() in ConvertBuffer_Rgb2Gray()

2026-07-28 15:31:43 -07:00

README.md

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README.md

core/

This directory contains the internal C++ implementation of the PDF specification. These modules are for internal use and may change without notice.

Subdirectories

PDFium's core is divided into several subdirectories, each with a specific responsibility:

fdrm/ (Rights Management): Provides cryptography primitives used for PDF security and encryption handling.
fpdfapi/ (PDF spec implementation): The central module that understands the PDF format, covering parsing, logical page representation, rendering coordination, and document editing.
fpdfdoc/ (Document Logic): Implements higher-level document features such as Bookmarks, Annotations, Interactive Forms (AcroForms), and Links.
fpdftext/ (Text Extraction): Specialized logic for extracting text, identifying reading order, and performing text searches within a page.
fxcodec/ (Codecs): Responsible for decoding various PDF stream formats. It depends on fxge for managing target bitmaps.
fxcrt/ (Common Runtime): The foundational layer providing base types, string handling, custom containers, and memory management utilities. It has no dependencies on other core modules.
fxge/ (Graphics Engine): Handles rendering primitives (paths, glyphs, bitmaps), font management abstractions (FreeType, Skia, AGG), and device drivers for different platforms.

Architectural Flow: Life of a Page

Building a rendered page involves several layers working in concert:

Parsing: fpdfapi/parser reads raw bytes and builds the PDF object graph (Dictionaries, Streams, etc.).
Decoding: As content is accessed, fxcodec decodes compressed data streams.
Logical Representation: fpdfapi/page interprets the objects into higher-level constructs like paths, text objects, and images.
Rendering: fpdfapi/render traverses the page objects and issues drawing commands to fxge.
Rasterization: fxge uses its rendering backend (e.g., AGG or Skia) to convert these primitives into final pixels in a device buffer.

Coordinate Systems

PDF documents use User Space, a coordinate system where the origin (0,0) is typically at the bottom-left of the page. Rendering devices (managed by fxge) usually use Device Space, where the origin is at the top-left.

core/ handles the complex affine transformations needed to map between these spaces, taking into account page rotation, scaling, and the specific transformation matrices (CTM) defined within content streams.