TextMagnifier in flutter

Question

是否有任何可用的软件包在扑动实现TextMagnifier?

我需要在编辑文本时使用TextFormField(如iphone)放大文本。

Answer 1

您可以在TextField中使用magnifierConfiguration属性

Flutter在3.7版本中增加了对文本放大的支持

你可以参考下面的例子:

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
void main() => runApp(const MyApp(text: 'Hello world!'));
class MyApp extends StatelessWidget {
const MyApp({
super.key,
this.textDirection = TextDirection.ltr,
required this.text,
});
final TextDirection textDirection;
final String text;
static const Size loupeSize = Size(200, 200);
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Padding(
padding: const EdgeInsets.symmetric(horizontal: 48.0),
child: Center(
child: TextField(
textDirection: textDirection,
// Create a custom magnifier configuration that
// this `TextField` will use to build a magnifier with.
magnifierConfiguration: TextMagnifierConfiguration(
magnifierBuilder:
(_, __, ValueNotifier<MagnifierInfo> magnifierInfo) =>
CustomMagnifier(
magnifierInfo: magnifierInfo,
),
),
controller: TextEditingController(text: text),
),
),
),
),
);
}
}
class CustomMagnifier extends StatelessWidget {
const CustomMagnifier({super.key, required this.magnifierInfo});
static const Size magnifierSize = Size(200, 200);
// This magnifier will consume some text data and position itself
// based on the info in the magnifier.
final ValueNotifier<MagnifierInfo> magnifierInfo;
@override
Widget build(BuildContext context) {
// Use a value listenable builder because we want to rebuild
// every time the text selection info changes.
// `CustomMagnifier` could also be a `StatefulWidget` and call `setState`
// when `magnifierInfo` updates. This would be useful for more complex
// positioning cases.
return ValueListenableBuilder<MagnifierInfo>(
valueListenable: magnifierInfo,
builder: (BuildContext context, MagnifierInfo currentMagnifierInfo, _) {
// We want to position the magnifier at the global position of the gesture.
Offset magnifierPosition = currentMagnifierInfo.globalGesturePosition;
// You may use the `MagnifierInfo` however you'd like:
// In this case, we make sure the magnifier never goes out of the current line bounds.
magnifierPosition = Offset(
clampDouble(
magnifierPosition.dx,
currentMagnifierInfo.currentLineBoundaries.left,
currentMagnifierInfo.currentLineBoundaries.right,
),
clampDouble(
magnifierPosition.dy,
currentMagnifierInfo.currentLineBoundaries.top,
currentMagnifierInfo.currentLineBoundaries.bottom,
),
);
// Finally, align the magnifier to the bottom center. The inital anchor is
// the top left, so subtract bottom center alignment.
magnifierPosition -= Alignment.bottomCenter.alongSize(magnifierSize);
return Positioned(
left: magnifierPosition.dx,
top: magnifierPosition.dy,
child: RawMagnifier(
magnificationScale: 2,
// The focal point starts at the center of the magnifier.
// We probably want to point below the magnifier, so
// offset the focal point by half the magnifier height.
focalPointOffset: Offset(0, magnifierSize.height / 2),
// Decorate it however we'd like!
decoration: const MagnifierDecoration(
shape: StarBorder(
side: BorderSide(
color: Colors.green,
width: 2,
),
),
),
size: magnifierSize,
),
);
});
}
}