ImageProvider

snippet.packages.flutter.lib.src.painting.image_provider.235.

  

// ignore_for_file: directives_ordering
// ignore_for_file: unnecessary_import
// ignore_for_file: unused_import
// ignore_for_file: unused_element
// ignore_for_file: unused_local_variable
import 'dart:async';
import 'dart:convert';
import 'dart:math' as math;
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/painting.dart';
import 'package:flutter/physics.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/semantics.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/animation.dart';
import 'package:flutter/services.dart';

// From: packages/flutter/lib/src/painting/image_provider.dart:235
class MyImage extends StatefulWidget {
  const MyImage({
    Key? key,
    required this.imageProvider,
  }) : super(key: key);

  final ImageProvider imageProvider;

  @override
  State createState() => _MyImageState();
}

class _MyImageState extends State {
  ImageStream? _imageStream;
  ImageInfo? _imageInfo;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    // We call _getImage here because createLocalImageConfiguration() needs to
    // be called again if the dependencies changed, in case the changes relate
    // to the DefaultAssetBundle, MediaQuery, etc, which that method uses.
    _getImage();
  }

  @override
  void didUpdateWidget(MyImage oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.imageProvider != oldWidget.imageProvider) {
      _getImage();
    }
  }

  void _getImage() {
    final ImageStream? oldImageStream = _imageStream;
    _imageStream = widget.imageProvider.resolve(createLocalImageConfiguration(context));
    if (_imageStream!.key != oldImageStream?.key) {
      // If the keys are the same, then we got the same image back, and so we don't
      // need to update the listeners. If the key changed, though, we must make sure
      // to switch our listeners to the new image stream.
      final ImageStreamListener listener = ImageStreamListener(_updateImage);
      oldImageStream?.removeListener(listener);
      _imageStream!.addListener(listener);
    }
  }

  void _updateImage(ImageInfo imageInfo, bool synchronousCall) {
    setState(() {
      // Trigger a build whenever the image changes.
      _imageInfo?.dispose();
      _imageInfo = imageInfo;
    });
  }

  @override
  void dispose() {
    _imageStream?.removeListener(ImageStreamListener(_updateImage));
    _imageInfo?.dispose();
    _imageInfo = null;
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return RawImage(
      image: _imageInfo?.image, // this is a dart:ui Image object
      scale: _imageInfo?.scale ?? 1.0,
    );
  }
}