Graphics Toolkit

The Xous UX stack consists of three levels:

  1. Modals and Menus
  2. The GAM (Graphical Abstraction Manager)
  3. The graphics-server


Modals and Menus

The Modals and Menu objects are pre-defined primitives that simplify the creation of Notifications, Checkboxes, Radioboxes, Text Entry boxes, Progress Bars, and Menus. They are as close as you get to a graphics toolkit in Xous.


Xous has a security-aware UX infrastructure that aims to make it difficult for rogue processes to pop up dialog boxes that could visually mimic system messages and password boxes.

The GAM is a layer that intermediates between the graphics toolkit and the hardware drivers, and enforces these security policies. It does this through the Canvas and Layout primitives.

The Canvas enforces a particular trust level associated with a region of the screen. White text on a black background is reserved for secure, trusted messages, and the GAM in combination with the trust level encoded in a Canvas is responsible for enforcing that rule. This is also where the deface operation occurs, the series of random lines that appear on items in the background.

Layouts contain one or more Canvas objects and are used to define, at a coarse level, regions of the screen, such as where the status bar belongs, the IME, and so forth.

Graphics Server

The graphics-server is responsible for rendering primitives such as circles, lines, and glyphs to the frame buffer. It places no restrictions on where pixels may be placed.

The graphics-server uses the xous-names registry mechanism to restrict its access. No user processes can talk directly to it as a result.