Creating a Cairo-Inspired Graphics Library for MetaTrader 5 (Part 1): Why the terminal needs its own 2D-renderer

Introduction

Modern trading interfaces demand more than a grid of rectangles: rounded cards, rings and donuts, semi-transparent layers, smooth gradients, and arbitrary polygons are all standard UI ingredients. MQL5's native chart objects and even the standard CCanvas fall short: corners are square, fills are hard-edged, there is no true alpha in object background colors, geometry is whole-number only, and object counts can quickly affect responsiveness. At the same time, we want to stay entirely inside the terminal—no DLLs, no external tools—and present the result as a single chart object.

This series takes a different route. Instead of inventing a new architecture, we borrow the compact, battle-tested design of Cairo. Its core idea—keeping geometry (paths) separate from paint (sources), then resolving them through a per-pixel coverage mask before compositing onto the destination—provides a common foundation for smooth, scalable rendering across different shapes. Over the coming parts, we will implement that model in pure MQL5, one small, verifiable step at a time.

Part 1 establishes the rendering foundation: a single ARGB color representation and a reusable pixel surface bound to one OBJ_BITMAP_LABEL . From there, the later parts will change how pixels are selected and painted, while the mechanism that delivers them to the chart remains the same.