Sandro Begashvili / Профиль

Learn how a viewer opens a PDF backwards, why xref entries must be exactly 20 bytes, and how a two-character change falsifies multiple offsets. We reproduce three typical failures, compare results in PDFium and pypdf, and extract four strict checks a generator must pass. The included PdfValidate.mqh class for MQL5 applies these checks and returns actionable offsets and object numbers for reliable testing beyond “it opens”.

Part 5 adds a fill rule to the rasterizer and a stroke helper to the path. The engine now supports both non-zero and even-odd fills via a single enum parameter, enabling rings, true borders that do not repaint interiors, and glyph counters. AddThickLine() builds strokes from fills in one path and one pass, preserving uniform opacity at joints and showing why strokes require the non-zero rule.

The rasterizer now accumulates exact span coverage in X and sampled coverage in Y, and blends it via CairoBlendOver on straight ARGB. CairoAaSamples sets the number of vertical samples at runtime, making the cost nearly linear and localized to edges. Readers get smoother boundaries, correct compositing of translucent shapes, and controllable performance.

Part 3 implements a scanline rasterizer in pure MQL5. We convert path segments into top‑down edges, sweep each row, sort crossings, and apply the non‑zero winding rule to decide which pixels are inside. The result is a single Fill(path, color, buffer, w, h) routine that draws rectangles, stars, glyphs, or 2000‑edge shapes without per‑shape code, ready to integrate into your MQL5 projects.

This article shows how a PDF works as plain text by hand‑written two files: a 592‑byte page and an 885‑byte trade ticket. It explains the file structure (header, body, xref, trailer), the required page objects and resources, and the operators that draw text, then provides an MQL5 script to generate them. First part of a pure‑MQL5 PDF library series.

Во второй части мы добавим слой геометрии в графическую библиотеку для MetaTrader 5, создаваемую по образцу Cairo. В ней определяется путь из точек с координатами двойной точности, сгруппированных в контуры, сохраняется признак того, является ли контур открытым или замкнутым, а вершины хранятся в плоском массиве с индексами начала контуров. Мы реализуем методы MoveTo, LineTo и Close, добавим базовые вспомогательные методы для построения фигур и демонстрационный пример, который отображает построенную геометрию для визуальной проверки и повторного использования.