The X Rendering Extension (Render or XRender) is an X Window System extension to implement Porter-Duff image compositing in the X server. It is designed to target the 3D graphics capabilities of newer video cards. It was written by Keith Packard in 2000 and was first released with XFree86 version 4.0.1.

It provides several rendering operations and also does alpha blending. At present it is primarily used to implement antialiased fonts, but is expected to be used to implement drop shadows and translucency.

Geometric figures are rendered by client-side tesselation into either triangles or trapezoids. Text is drawn by loading the glyphs into the server and rendering as a group.

References

• The X Rendering Extension (Keith Packard, 23 July 2004)
• A New Rendering Model for X (Keith Packard, USENIX 2000)
• High Performance X Servers in the Kdrive Architecture (Eric Anholt, USENIX '04)
• Xorg Glossary (X.Org)

X Window extensions | Freedesktop.org