summary
Semantics may be a strange component of Flutter, and most people would not think of using Semantics in their development if they had not encountered it. The structure is as follows:
Semantics({
Key? key,
Widget? child,
bool container = false,
bool explicitChildNodes = false,
bool excludeSemantics = false,
bool? enabled,
bool? checked,
bool? selected,
bool? toggled,
bool? button,
bool? slider,
bool? link,
bool? header,
bool? textField,
bool? readOnly,
bool? focusable,
bool? focused,
bool? inMutuallyExclusiveGroup,
bool? obscured,
bool? multiline,
bool? scopesRoute,
bool? namesRoute,
bool? hidden,
bool? image,
bool? liveRegion,
int? maxValueLength,
int? currentValueLength,
String? label,
String? value,
String? increasedValue,
String? decreasedValue,
String? hint,
String? onTapHint,
String? onLongPressHint,
TextDirection? textDirection,
SemanticsSortKey? sortKey,
SemanticsTag? tagForChildren,
VoidCallback? onTap,
VoidCallback? onLongPress,
VoidCallback? onScrollLeft,
VoidCallback? onScrollRight,
VoidCallback? onScrollUp,
VoidCallback? onScrollDown,
VoidCallback? onIncrease,
VoidCallback? onDecrease,
VoidCallback? onCopy,
VoidCallback? onCut,
VoidCallback? onPaste,
VoidCallback? onDismiss,
MoveCursorHandler? onMoveCursorForwardByCharacter,
MoveCursorHandler? onMoveCursorBackwardByCharacter,
SetSelectionHandler? onSetSelection,
VoidCallback? onDidGainAccessibilityFocus,
VoidCallback? onDidLoseAccessibilityFocus,
Map<CustomSemanticsAction, VoidCallback>? customSemanticsActions,
}) : this.fromProperties(...)
Copy the codeThere are approximately 54 parameters ？？？？？
Semantics on the other hand is the component that developers are most familiar with?
use
Attribute interpretation
| attribute | meaning |
|---|---|
| child | Child components |
| container | Whether a new semantic node is being introduced |
| explicitChildNodes | Whether to force the display of semantic information for child widgets |
| excludeSemantics | Whether to exclude semantics from child widgets |
| enabled | Whether the available |
| checked | Check whether the CheckBox is selected |
| selected | If the selected |
| toggled | Whether to toggle |
| button | Whether or not the Button |
| slider | Whether the slider |
| link | Whether the link |
| header | Whether the header |
| textField | Whether the textField |
| readOnly | Whether the system |
| focusable | Whether focatable or not |
| focused | Whether or not the focus |
| inMutuallyExclusiveGroup | Whether or not compatible |
| obscured | Whether the fuzzy |
| multiline | If multiple lines |
| scopesRoute | Whether to declare the route name |
| namesRoute | Whether to contain semantic labels of routes |
| hidden | Whether to hide |
| image | Whether the image |
| liveRegion | Whether active |
| maxValueLength | The maximum length |
| currentValueLength | The current length |
| label | The text description of the Widget |
| value | value |
| increasedValue | value-added |
| decreasedValue | impairment |
| hint | prompt |
| onTapHint | Click on the hint |
| onLongPressHint | Long according to the prompt |
| textDirection | The text direction |
| sortKey | The sorting |
| tagForChildren | Child node label |
| onTap | Click on the event |
| onLongPress | Long press event |
| onScrollLeft | The left sliding event |
| onScrollRight | The right sliding event |
| onScrollUp | Slide the event |
| onScrollDown | In event |
| onIncrease | Appreciation event |
| onDecrease | Impairment events |
| onCopy | copy |
| onCut | cut |
| onPaste | paste |
| onDismiss | dismiss |
| onMoveCursorForwardByCharacter | The character cursor moves forward |
| onMoveCursorBackwardByCharacter | The character cursor moves back |
| onSetSelection | Select events |
| onDidGainAccessibilityFocus | Get focus |
| onDidLoseAccessibilityFocus | Lose focus |
| customSemanticsActions | Custom events |
Sorry for the inaccurate translation!
classification
- Semantics
A widget that describes the specific semantics of the widget tree. Use assistive tools, search engines, and other semantic analysis software to determine the meaning of your application.
- MergeSemantics
A widget that incorporates the semantics of its descendants.
- ExcludeSemantics
Remove any widget whose descendants have any semantics
use
Flexible(
child: Semantics(
label: MaterialLocalizations.of(context).selectYearSemanticsLabel,
excludeSemantics: true,
button: true,
child: Container(
height: _subHeaderHeight,
child: InkWell(
onTap: widget.onTitlePressed,
...
Copy the codeExplain InkWell, i.e. what is the button on the screen
// dayWidget
child: Semantics(
label: '${localizations.formatDecimal(day)}, ${localizations.formatFullDate(dayToBuild)}',
selected: isSelectedDay,
excludeSemantics: true,
child: dayWidget,
),
...
dayItems.add(dayWidget);
Copy the codeDayWidget is a component of the calendar that comes with Flutter. Finally, add all the days of the month to the dayItems list to display the calendar of the month in one place. label: ‘ localizations.formatDecimal(day),{localizations.formatDecimal(day)}, Localizations. FormatDecimal (day), {localizations. FormatFullDate (dayToBuild)} ‘, is explained which day is the day, excludeSemantics: True: deletes any descendant widget with semantics. If any descendant widget has semantics, it is not recognized and invalid.
.return MergeSemantics(
child: Semantics(
enabled: widget.enabled,
button: true,
child: InkWell(
onTap: widget.enabled ? handleTap : null, canRequestFocus: widget.enabled, mouseCursor: effectiveMouseCursor, child: item, ), ) ); .Copy the codeThis is part of the PopupMenuItem code. MergeSemantics merges the child widgets semantics, and if there are other items in a PopupMenuItem, they merge into one.
note
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
showSemanticsDebugger:true.Copy the codeIf the showSemanticsDebugger is set to false and true, different views will appear:
It is obvious that when showSemanticsDebugger is true, the view is much different, less aesthetically pleasing, but much easier to read and manipulate, which is why Semantics is often used to help visually impaired people.