Display Classes

The classes definied in ultimo_display handle interaction with display devices attached to the microcontroller. Since these devices are diverse, the package is more of a framework for writing compatible devices than a collection of concrete implementations.

The package provides two classes: an abstract base class text_device.ATextDevice and a concrete framebuffer-based implementation framebuffer_text_device.FrameBufferTextDevice.

Warning

This API may change in the future depending on the capabilities of other types of display hardware. In particular, it may grow support for drawing text in different colors on displays for which it is appropriate.

Text Devices

The concept of an ATextDevice is that it represents display of monospaced text in rows and columns which has a cursor that can be displayed. The API is fairly straightforward, providing methods to display text at a (column, row) position, erase a number of characters at a (column, row) position, set the cursor’s (column, row) position, hide the cursor, and clear the display.

It also provides a ATextDevice.display_text() method that creates an Ultimo Consumer that expects strings and displays the values at a location.

Concrete subclasses will need to provide implementations of most of these methods, although ATextDevice.erase() and ATextDevice.display_text() have default implementations which may suffice for many devices.

FrameBuffer Text Devices

The FrameBufferTextDevice provides a concrete implementation of ATextDevice using a framebuf.FrameBuffer or another object which implements the same API.

It expects to be provided with an already-allocated buffer of the appropriate size for the number of rows and columns, and the pixel depth, along with the size of the display in characters, the pixel format, and optional background and foreground colors.

Warning

The FrameBufferTextDevice has not been extensively tested.