Added BuildContext parameter to TextEditingController.buildTextSpan
Summary
#A BuildContext
parameter was added to TextEditingController.buildTextSpan
.
Classes that extend or implement TextEditingController
and override buildTextSpan
need to add the BuildContext
parameter to the signature to make it a valid override.
Callers of TextEditingController.buildTextSpan
need to pass a BuildContext
to the call.
Context
#TextEditingController.buildTextSpan
is called by EditableText
on its controller to create the TextSpan
that it renders.
buildTextSpan
can be overridden in custom classes that extend
TextEditingController
. This allows classes extending
TextEditingController
override buildTextSpan
to change
the style of parts of the text, for example, for rich text editing.
Any state that is required by buildTextSpan
(other than the TextStyle
and withComposing
arguments)
needed to be passed into the class that extends
TextEditingController
.
Description of change
#With the BuildContext
available, users can access
InheritedWidgets
inside buildTextSpan
to retrieve state required to style the text,
or otherwise manipulate the created TextSpan
.
Consider the example where we have a
HighlightTextEditingController
that wants to
highlight text by setting its color to Theme.accentColor
.
Before this change the controller implementation would look like this:
class HighlightTextEditingController extends TextEditingController {
HighlightTextEditingController(this.highlightColor);
final Color highlightColor;
@override
TextSpan buildTextSpan({TextStyle? style, required bool withComposing}) {
return super.buildTextSpan(style: TextStyle(color: highlightColor), withComposing: withComposing);
}
And users of the controller would need to pass the color when creating the controller.
With the BuildContext
parameter available,
the HighlightTextEditingController
can directly access
Theme.accentColor
using Theme.of(BuildContext)
:
class HighlightTextEditingController extends TextEditingController {
@override
TextSpan buildTextSpan({required BuildContext context, TextStyle? style, required bool withComposing}) {
final Color color = Theme.of(context).accentColor;
return super.buildTextSpan(context: context, style: TextStyle(color: color), withComposing: withComposing);
}
}
Migration guide
#Overriding TextEditingController.buildTextSpan
#Add a required BuildContext context
parameter to the
signature of the buildTextSpan
override.
Code before migration:
class MyTextEditingController {
@override
TextSpan buildTextSpan({TextStyle? style, required bool withComposing}) {
/* ... */
}
}
Example error message before migration:
'MyTextEditingController.buildTextSpan' ('TextSpan Function({TextStyle? style, required bool withComposing})') isn't a valid override of 'TextEditingController.buildTextSpan' ('TextSpan Function({required BuildContext context, TextStyle? style, required bool withComposing})').
Code after migration:
class MyTextEditingController {
@override
TextSpan buildTextSpan({required BuildContext context, TextStyle? style, required bool withComposing}) {
/* ... */
}
}
Calling TextEditingController.buildTextSpan
#Pass a named parameter 'context' of type
BuildContext
to the call.
Code before migration:
TextEditingController controller = /* ... */;
TextSpan span = controller.buildTextSpan(withComposing: false);
Error message before migration:
The named parameter 'context' is required, but there's no corresponding argument.
Try adding the required argument.
Code after migration:
BuildContext context = /* ... */;
TextEditingController controller = /* ... */;
TextSpan span = controller.buildTextSpan(context: context, withComposing: false);
Timeline
#Landed in version: 1.26.0
In stable release: 2.0.0
References
#API documentation:
Relevant issues:
Relevant PRs:
- Reland "Add BuildContext parameter to TextEditingController.buildTextSpan" #73510
- Revert "Add BuildContext parameter to TextEditingController.buildTextSpan" #73503
- Add BuildContext parameter to TextEditingController.buildTextSpan #72344
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