rendercheck

rendercheck [options]

-h, --help
    Displays a brief help message explaining command usage and options.

-v, --version
    Prints the version information of the rendercheck utility.

The rendercheck command is a diagnostic utility for the X Window System. Its primary purpose is to test and report on the capabilities of the X server's RENDER extension. This extension, introduced in X11, provides advanced graphics operations such as alpha blending, anti-aliasing, and compositing, which are crucial for modern desktop environments and applications.

When executed, rendercheck connects to the active X server and queries its RENDER extension version. It then systematically checks for support of various RENDER operations, including different pixel formats, picture formats, and geometric primitive rendering capabilities (e.g., trapezoids, triangles). The output typically lists each checked feature, indicating whether it is SUPPORTED or UNSUPPORTED by the server.

This tool is invaluable for debugging graphics issues, verifying that display drivers are correctly exposing RENDER functionality, or simply understanding the graphic capabilities of a specific X server setup. It helps ensure that applications requiring advanced rendering features can operate optimally.

Diagnostic Only: rendercheck merely reports capabilities; it does not resolve or fix underlying issues.

X Window System Specific: This command is exclusively relevant to the X Window System and has no utility in environments using other display servers like Wayland.

RENDER Extension Required: For meaningful results, the X server must have the RENDER extension enabled. If not, the output might indicate a complete lack of RENDER support.

The output of rendercheck provides a detailed list of RENDER features. Each entry typically shows a feature name followed by a status, such as 'SUPPORTED' or 'UNSUPPORTED'. 'SUPPORTED' indicates the X server and its drivers correctly implement that specific RENDER operation or pixel format. 'UNSUPPORTED' suggests a lack of implementation, a disabled feature, or a driver issue. Pay attention to features marked 'UNSUPPORTED' if an application or desktop environment is experiencing rendering artifacts or performance problems, as it might point to missing required capabilities.

The RENDER extension is fundamental for modern graphical interfaces on X. It enables transparency effects (alpha blending), smooth edges on fonts and graphics (anti-aliasing), and efficient off-screen rendering and compositing (used by desktop compositors like Compiz, KWin, or Mutter). Without proper RENDER support, user interfaces may appear blocky, lack transparency, or suffer from poor performance, impacting the overall user experience.

The RENDER extension was a significant addition to the X Window System, first introduced in X11R6.6 (part of X.Org 6.6) around 2000-2001. It was designed to address the growing need for sophisticated 2D graphics operations like alpha blending, anti-aliasing, and compositing, which were becoming standard in modern user interfaces. rendercheck was developed concurrently as a crucial diagnostic tool within the X.Org project. It became part of the standard xorg-x11-apps or xorg-x11-server-utils distribution, serving as a reliable way to verify the correct implementation and capabilities of the RENDER extension across different X server and graphics driver configurations. Its core functionality has remained largely unchanged since its inception.

xdpyinfo(1), xrandr(1), glxinfo(1)