这段代码有什么问题？
我希望表情符号也像文本一样与文本一起正确缩放，但表情符号会跳跃并变大
如果我只放表情符号也会发生同样的问题
主程序.dart
Scaffold(
appBar: AppBar(),
body: SizedBox(
height: Get.height,
width: Get.width,
child: Stack(
children: [
TransformDemo(),
],
),
),
);
}
变换演示.dart
import 'package:flutter/material.dart';
import 'package:photo_editor/matrix_gesture_detector.dart';
class TransformDemo extends StatelessWidget {
@override
Widget build(BuildContext context) {
final ValueNotifier<Matrix4> notifier = ValueNotifier(Matrix4.identity());
return MatrixGestureDetector(
onMatrixUpdate: (m, tm, sm, rm) {
notifier.value = m;
},
child: AnimatedBuilder(
animation: notifier,
builder: (ctx, child) {
return Transform(
transform: notifier.value,
child: Align(
alignment: Alignment.center,
child: FittedBox(
// fit: BoxFit.contain,
child: Text('Hello world ???? ', style: TextStyle(fontSize: 60),)
// child: Icon(Icons.favorite, color: Colors.deepPurple.withOpacity(0.5), size: 200),
),
),
);
},
),
);
}
}
矩阵手势检测器.dart
import 'dart:math';
import 'package:flutter/widgets.dart';
typedef MatrixGestureDetectorCallback = void Function(
Matrix4 matrix,
Matrix4 translationDeltaMatrix,
Matrix4 scaleDeltaMatrix,
Matrix4 rotationDeltaMatrix);
/// [MatrixGestureDetector] detects translation, scale and rotation gestures
/// and combines them into [Matrix4] object that can be used by [Transform] widget
/// or by low level [CustomPainter] code. You can customize types of reported
/// gestures by passing [shouldTranslate], [shouldScale] and [shouldRotate]
/// parameters.
///
class MatrixGestureDetector extends StatefulWidget {
/// [Matrix4] change notification callback
///
final MatrixGestureDetectorCallback onMatrixUpdate;
/// The [child] contained by this detector.
///
/// {@macro flutter.widgets.child}
///
final Widget child;
/// Whether to detect translation gestures during the event processing.
///
/// Defaults to true.
///
final bool shouldTranslate;
/// Whether to detect scale gestures during the event processing.
///
/// Defaults to true.
///
final bool shouldScale;
/// Whether to detect rotation gestures during the event processing.
///
/// Defaults to true.
///
final bool shouldRotate;
/// Whether [ClipRect] widget should clip [child] widget.
///
/// Defaults to true.
///
final bool clipChild;
/// The hit test behavior, passed to the underlying GestureDetector.
///
/// Defaults to HitTestBehavior.deferToChild
///
final HitTestBehavior behavior;
/// When set, it will be used for computing a "fixed" focal point
/// aligned relative to the size of this widget.
final Alignment? focalPointAlignment;
const MatrixGestureDetector({
Key? key,
required this.onMatrixUpdate,
required this.child,
this.shouldTranslate = true,
this.shouldScale = true,
this.shouldRotate = true,
this.clipChild = true,
this.focalPointAlignment,
this.behavior = HitTestBehavior.deferToChild,
}) : super(key: key);
@override
_MatrixGestureDetectorState createState() => _MatrixGestureDetectorState();
///
/// Compose the matrix from translation, scale and rotation matrices - you can
/// pass a null to skip any matrix from composition.
///
/// If [matrix] is not null the result of the composing will be concatenated
/// to that [matrix], otherwise the identity matrix will be used.
///
static Matrix4 compose(Matrix4? matrix, Matrix4? translationMatrix,
Matrix4? scaleMatrix, Matrix4? rotationMatrix) {
if (matrix == null) matrix = Matrix4.identity();
if (translationMatrix != null) matrix = translationMatrix * matrix;
if (scaleMatrix != null) matrix = scaleMatrix * matrix;
if (rotationMatrix != null) matrix = rotationMatrix * matrix;
return matrix!;
}
///
/// Decomposes [matrix] into [MatrixDecomposedValues.translation],
/// [MatrixDecomposedValues.scale] and [MatrixDecomposedValues.rotation] components.
///
static MatrixDecomposedValues decomposeToValues(Matrix4 matrix) {
var array = matrix.applyToVector3Array([0, 0, 0, 1, 0, 0]);
Offset translation = Offset(array[0], array[1]);
Offset delta = Offset(array[3] - array[0], array[4] - array[1]);
double scale = delta.distance;
double rotation = delta.direction;
return MatrixDecomposedValues(translation, scale, rotation);
}
}
class _MatrixGestureDetectorState extends State<MatrixGestureDetector> {
Matrix4 translationDeltaMatrix = Matrix4.identity();
Matrix4 scaleDeltaMatrix = Matrix4.identity();
Matrix4 rotationDeltaMatrix = Matrix4.identity();
Matrix4 matrix = Matrix4.identity();
@override
Widget build(BuildContext context) {
Widget child =
widget.clipChild ? ClipRect(child: widget.child) : widget.child;
return GestureDetector(
behavior: widget.behavior,
onScaleStart: onScaleStart,
onScaleUpdate: onScaleUpdate,
child: child,
);
}
_ValueUpdater<Offset> translationUpdater = _ValueUpdater(
value: Offset.zero,
onUpdate: (oldVal, newVal) => newVal - oldVal,
);
_ValueUpdater<double> scaleUpdater = _ValueUpdater(
value: 1.0,
onUpdate: (oldVal, newVal) => newVal / oldVal,
);
_ValueUpdater<double> rotationUpdater = _ValueUpdater(
value: 0.0,
onUpdate: (oldVal, newVal) => newVal - oldVal,
);
void onScaleStart(ScaleStartDetails details) {
translationUpdater.value = details.focalPoint;
scaleUpdater.value = 1.0;
rotationUpdater.value = 0.0;
}
void onScaleUpdate(ScaleUpdateDetails details) {
translationDeltaMatrix = Matrix4.identity();
scaleDeltaMatrix = Matrix4.identity();
rotationDeltaMatrix = Matrix4.identity();
// handle matrix translating
if (widget.shouldTranslate) {
Offset translationDelta = translationUpdater.update(details.focalPoint);
translationDeltaMatrix = _translate(translationDelta);
matrix = translationDeltaMatrix * matrix;
}
final focalPointAlignment = widget.focalPointAlignment;
final focalPoint = focalPointAlignment == null ?
details.localFocalPoint :
focalPointAlignment.alongSize(context.size!);
// handle matrix scaling
if (widget.shouldScale && details.scale != 1.0) {
double scaleDelta = scaleUpdater.update(details.scale);
scaleDeltaMatrix = _scale(scaleDelta, focalPoint);
matrix = scaleDeltaMatrix * matrix;
}
// handle matrix rotating
if (widget.shouldRotate && details.rotation != 0.0) {
double rotationDelta = rotationUpdater.update(details.rotation);
rotationDeltaMatrix = _rotate(rotationDelta, focalPoint);
matrix = rotationDeltaMatrix * matrix;
}
widget.onMatrixUpdate(
matrix, translationDeltaMatrix, scaleDeltaMatrix, rotationDeltaMatrix);
}
Matrix4 _translate(Offset translation) {
var dx = translation.dx;
var dy = translation.dy;
// ..[0] = 1 # x scale
// ..[5] = 1 # y scale
// ..[10] = 1 # diagonal "one"
// ..[12] = dx # x translation
// ..[13] = dy # y translation
// ..[15] = 1 # diagonal "one"
return Matrix4(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, dx, dy, 0, 1);
}
Matrix4 _scale(double scale, Offset focalPoint) {
var dx = (1 - scale) * focalPoint.dx;
var dy = (1 - scale) * focalPoint.dy;
// ..[0] = scale # x scale
// ..[5] = scale # y scale
// ..[10] = 1 # diagonal "one"
// ..[12] = dx # x translation
// ..[13] = dy # y translation
// ..[15] = 1 # diagonal "one"
return Matrix4(scale, 0, 0, 0, 0, scale, 0, 0, 0, 0, 1, 0, dx, dy, 0, 1);
}
Matrix4 _rotate(double angle, Offset focalPoint) {
var c = cos(angle);
var s = sin(angle);
var dx = (1 - c) * focalPoint.dx + s * focalPoint.dy;
var dy = (1 - c) * focalPoint.dy - s * focalPoint.dx;
// ..[0] = c # x scale
// ..[1] = s # y skew
// ..[4] = -s # x skew
// ..[5] = c # y scale
// ..[10] = 1 # diagonal "one"
// ..[12] = dx # x translation
// ..[13] = dy # y translation
// ..[15] = 1 # diagonal "one"
return Matrix4(c, s, 0, 0, -s, c, 0, 0, 0, 0, 1, 0, dx, dy, 0, 1);
}
}
typedef _OnUpdate<T> = T Function(T oldValue, T newValue);
class _ValueUpdater<T> {
final _OnUpdate<T> onUpdate;
T value;
_ValueUpdater({
required this.value,
required this.onUpdate,
});
T update(T newValue) {
T updated = onUpdate(value, newValue);
value = newValue;
return updated;
}
}
class MatrixDecomposedValues {
/// Translation, in most cases useful only for matrices that are nothing but
/// a translation (no scale and no rotation).
final Offset translation;
/// Scaling factor.
final double scale;
/// Rotation in radians, (-pi..pi) range.
final double rotation;
MatrixDecomposedValues(this.translation, this.scale, this.rotation);
@override
String toString() {
return 'MatrixDecomposedValues(translation: $translation, scale: ${scale.toStringAsFixed(3)}, rotation: ${rotation.toStringAsFixed(3)})';
}
}
