ver Jan10th

a quick introduction to accessibility tree interface

desktop_env/server/README.md

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+<!-- vimc: call SyntaxRange#Include('```xml', '```', 'xml', 'NonText'): -->
+<!-- vimc: call SyntaxRange#Include('```css', '```', 'css', 'NonText'): -->
+<!-- vimc: call SyntaxRange#Include('```sh', '```', 'sh', 'NonText'): -->
+
+### About the Converted Accessibility Tree
+
+For several applications like Firefox or Thunderbird, you should first enable
+
+```sh
+gsettings set org.gnome.desktop.interface toolkit-accessibility true
+```
+
+to see their accessibility tree.
+
+#### Example of AT
+
+An example of a node:
+
+```xml
+<section xmlns:attr="uri:deskat:attributes.at-spi.gnome.org" attr:class="subject" st:enabled="true" cp:screencoord="(1525, 169)", cp:windowcoord="(342, 162)", cp:size="(327, 21)">
+    歡迎使用新的 Outlook.com 帳戶
+</section>
+```
+
+An example of a tree:
+
+```xml
+<desktop-frame ...>
+    <application name="Thunderbird" ...>
+        ... <!-- nodes of windows -->
+    </application>
+    ...
+</desktop-frame>
+```
+
+#### Useful attributes
+
+1. `name` - shows the name of application, title of window, or name of some
+   component
+2. `attr:class` - somewhat the same role as `class` in HTML
+3. `attr:id` - somewhat the same role as `id` in HTML
+4. `cp:screencoord` - absolute coordinator on the screen
+5. `cp:windowcoord` - relative coordinator in the window
+6. `cp:size` - the size
+
+Also several states like `st:enabled` and `st:visible` can be indicated. A full
+state list is available at
+<https://gitlab.gnome.org/GNOME/pyatspi2/-/blob/master/pyatspi/state.py?ref_type=heads>.
+
+#### How to use it in evaluation
+
+See example `thunderbird/12086550-11c0-466b-b367-1d9e75b3910e.json` and
+function `check_accessibility_tree` in `metrics/general.py`. You can use CSS
+selector or XPath to reference a target nodes. You can also check its text
+contents.
+
+An example of a CSS selector:
+
+```css
+application[name=Thunderbird] page-tab-list[attr|id=\"tabmail-tabs\"]>page-tab[name=\"About Profiles\"]
+```
+
+This selector will select the page tab of profile manager in Thunderbird (if open).
+
+For usage of CSS selector: <https://www.w3.org/TR/selectors-3/>. For usage of XPath: <https://www.w3.org/TR/xpath-31/>.