image - 如何在 Flutter/Dart 中将 Assets 图像转换为位图？

Question

我需要比较两个图像，因此我需要将这两个图像( Assets )解码为位图。我试过这个:

import 'package:flutter/services.dart';
import 'package:image/image.dart';

var imageData = await rootBundle.load("assets/images/test.png");
Image firstImage = Image.fromBytes(100, 100, imageData.buffer.asUint8List());
int pixel = firstImage.getPixel(5, 0);
print('$pixel');

但它不起作用，因为在我将 getPixel(x, y) 的第二个参数设置为除 0 之外的任何值后，它会抛出异常:

E/flutter (11752): [ERROR:flutter/shell/common/shell.cc(199)] Dart Error: Unhandled exception:
E/flutter (11752): RangeError (index): Index out of range: index should be less than 86: 101
E/flutter (11752): #0      _Uint32ArrayView.[] (dart:typed_data-patch/typed_data_patch.dart:3999:7)
E/flutter (11752): #1      Image.getPixel (package:image/src/image.dart:409:37)

我也这样试过:

Image firstImage = decodeImage(new File('assets/images/test.png').readAsBytesSync());
int pixel = firstImage.getPixel(1, 1);
print('$pixel');

但有下一个异常(exception):

E/flutter (11752): FileSystemException: Cannot open file, path = 'assets/images/test.png' (OS Error: No such file or directory, errno = 2)

所以我正在寻找一种解决方案，它可以帮助我将我的资源转换为位图，这样我就可以获得每张图像的每个像素的颜色。

Answer 1

试试这个:

import 'package:image/image.dart' as img;

...

ByteData imageBytes = await rootBundle.load('assets/images/test.png');
List<int> values = imageBytes.buffer.asUint8List();
img.Image photo;
photo = img.decodeImage(values);
int pixel = photo.getPixel(5, 0);