DirectWrite

DirectWrite is a Windows API for rendering and layout of text in applications. Part of the DirectX family, it provides a modern, device-independent pipeline designed to replace older GDI-based text rendering. DirectWrite supports high-DPI displays, international scripts, and advanced typography, enabling accurate measurement, layout, and rendering of diverse fonts and text.

Introduced to modern Windows platforms as a successor to previous text engines, DirectWrite exposes components for font management, text formatting, and rendering. It is used by system components and many third-party applications to achieve clear, scalable text rendering across languages and scripts.

Core concepts include a factory for creating objects, font collections and font faces, and text formats with properties such as font family, size, weight, and locale. Text layout objects measure and arrange runs of text, while typography objects enable OpenType features like ligatures, kerning, and stylistic sets. Rendering can be performed by clients via custom renderers or by built-in rendering pipelines.

Rendering integrates with Direct2D to draw text, applying ClearType subpixel rendering for LCD screens. DirectWrite also supports color fonts and OpenType color glyphs, and provides bidirectional text, script shaping, and glyph substitution to support complex scripts.

Developers access DirectWrite through COM-based interfaces (for example, IDWriteFactory, IDWriteFontCollection, IDWriteTextLayout) and can use it from C++ and other languages via wrappers. It remains a core component of Windows text rendering.