Mouse and Touchpad Support Added to Expo

U-Boot’s ‘expo’ toolkit is used for creating user interfaces, such as the configuration editor (cedit) and graphical boot menus (bootflow menu). Previously, user interaction with expo scenes was limited to the keyboard.

A recent 23-patch series introduces support for mouse and touchpad interaction.

New Input Handling

For devices where a mouse or touchpad is available, keyboard-only navigation can be inefficient. This update is intended to improve user interaction, particularly within complex screens like the configuration editor.

The core of this update is a new expo_send_click() function, which is designed to work similarly to the existing expo_send_key() function for processing user input.

The expo framework separates the processing of an event (like a click or keypress) from the handling of the resulting action. This series maintains that design, which allows expo to be integrated into different event loops. If a mouse is detected, expo will enable it by default.

Implementation Details

To enable mouse clicks, the framework required a method to determine which UI element exists at a specific (x, y) coordinate. This was implemented in several stages:

1. Coordinate Checking: New functions, such as scene_menu_within() and scene_textline_within(), have been added. These check if a given coordinate is within the bounding box of a menu item or an editable text field.
2. Scene-Level Clicks: The logic was then extended to the scene level, allowing a click to be routed to the correct object within the current scene. This includes handling for popup menus.
3. Input Polling: The main expo_poll() function was updated to check for both keyboard and mouse events.

Additional Changes

The series also includes a few other updates:

• Filled Boxes: The video API now supports drawing filled rectangles in addition to outlines.
• New Fonts: The Ubuntu Light and Bold fonts have been added.
• Testing: New tests for the mouse functionality have been added, including helpers to simulate clicks and verify the resulting actions.

This series expands U-Boot’s user interface capabilities by adding a new method for user input.