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Accessibility traversal order of tooltip changed

Contents

Summary

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During accessibility focus traversal, Tooltip.message is visited immediately after Tooltip.child.

Background

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The Tooltip widget usually wraps an interactive UI component such as a button, and shows a help message when long pressed. When the message is visible, assistive technologies should announce it after the button.

The Tooltip widget originally put Tooltip.message on an OverlayEntry when long pressed. As a result, Tooltip.message was not immediately after Tooltip.child in the semantics tree.

Migration guide

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This change moved the tooltip message in the semantics tree. You might see accessibility test failures if your tests expect a tooltip message to appear in a specific location in the semantics tree, when it is visible. Update any failing accessibility tests to adopt the new tooltip semantics order.

For example, if you constructed the following widget tree in your test:

dart
Directionality(
  textDirection: TextDirection.ltr,
  child: Overlay(
    initialEntries: <OverlayEntry>[
      OverlayEntry(
        builder: (BuildContext context) {
          return ListView(
            children: <Widget>[
              const Text('before'),
              Tooltip(
                key: tooltipKey,
                showDuration: const Duration(days: 365),
                message: 'message',
                child: const Text('child'),
              ),
              const Text('after'),
            ],
          );
        },
      ),
    ],
  ),
);

When the tooltip message is visible, the corresponding semantics tree before this change should look like this:

dart
SemanticsNode#0
 │
 ├─SemanticsNode#1
 │ │
 │ └─SemanticsNode#5
 │   │ flags: hasImplicitScrolling
 │   │ scrollChildren: 3
 │   │
 │   ├─SemanticsNode#2
 │   │   tags: RenderViewport.twoPane
 │   │   label: "before"
 │   │   textDirection: ltr
 │   │
 │   ├─SemanticsNode#3
 │   │   tags: RenderViewport.twoPane
 │   │   label: "child"
 │   │   tooltip: "message"
 │   │   textDirection: ltr
 │   │
 │   └─SemanticsNode#4
 │       tags: RenderViewport.twoPane
 │       label: "after"
 │       textDirection: ltr
 │
 └─SemanticsNode#6
     label: "message"
     textDirection: ltr

After this change, the same widget tree generates a slightly different semantics tree, as shown below. Node #6 becomes a child of node #3, instead of node #0.

dart
SemanticsNode#0
 │
 └─SemanticsNode#1
   │
   └─SemanticsNode#5
     │ flags: hasImplicitScrolling
     │ scrollChildren: 3
     │
     ├─SemanticsNode#2
     │   tags: RenderViewport.twoPane
     │   label: "before"
     │   textDirection: ltr
     │
     ├─SemanticsNode#3
     │ │ tags: RenderViewport.twoPane
     │ │ label: "child"
     │ │ tooltip: "message"
     │ │ textDirection: ltr
     │ │
     │ └─SemanticsNode#6
     │     label: "message"
     │     textDirection: ltr
     │
     └─SemanticsNode#4
         tags: RenderViewport.twoPane
         label: "after"
         textDirection: ltr

Timeline

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Landed in version: 3.16.0-11.0.pre
In stable release: 3.19.0

References

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API documentation:

Relevant PRs:

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