These cli tools are designed to help to debug accessibility problems in applications, primarily in web browsers.
ax_dump_tree to inspect accessibility tree of application ax_dump_events to watch accessibility events fired by application
Note: if you are on Windows, see convenience scripts section, it makes the tools easier to use on Windows.
autoninja -C out/Default ax_dump_tree ax_dump_events
The command generates ax_dump_tree and ax_dump_events executables in out/Default directory.
Turn on Accessibility for Terminal in Security & Privacy System Preferences.
Some applications keep accessibility inactive, which prevents them to generate accessible trees or emit events. Thus either:
CMD+F5) orChromium.app/Contents/MacOS/Chromium --force-renderer-accessibilityHelps to inspect accessibility trees of applications. Trees are dumped into console.
To dump an accessible tree, run: ax_dump_tree <options>
At your convenience the number of pre-defined application selectors are available: --chrome for Chrome browser --chromium for Chromium browser --firefox for Firefox browser --safari for Safari browser
--active-tab to dump a tree of active tab of selected browser.
You can also specify an application by its title: ax_dump_tree --pattern=title
Alternatively you can dump a tree by HWDN on Windows: --window=HWDN Note, to use a hex window handle prefix it with 0x.
Or by application PID on Mac and Linux: --pid=process_id
Other options: --json to output a tree in JSON format --filters=absolute_path_to_filters.txt to filter properties, use where the filters text file has a series of @ALLOW and/or @DENY lines. See example-tree-filters.txt in tools/accessibility/inspect. --help for help
The tool logs into console accessibility events fired by application.
To watch accessibility events, run: ax_dump_events <options>
Use these pre-defined application selectors to indicate application: --chrome for Chrome browser --chromium for Chromium browser --firefox for Firefox browser --safari for Safari browser
--active-tab to scope events to an active tab of selected browser.
You can also specify application by its title: --pattern=title
Or by application PID: --pid=process_id
Note: Windows only.
Run these scripts to avoid the difficulty of looking up the process id or window handle you want to inspect. Sometimes there may be several windows open for the given app, and disambuation. In this case, after you run the script, it will list top level windows/processes and ask you to re-run with an argument that includes a substring from the window title you want to inspect the tree/events for. For example, chrome-tree live will inspect a tab with the name “Live region tests” (the title matcher is case insensitive).