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我在本地目录中安装了 node-canvas 和 imagediff 并编写了一个测试示例来比较两个已经存在的图像文件。使用下面的代码运行得很好：

var Canvas = require('canvas')
    , imagediff = require('../lib/imagediff.js')
    , fs = require('fs')
    , path = require('path');

var goodFilePath = path.join(__dirname + '/../diffs/single/test_1_good.png')
    , newFilePath = path.join(__dirname + '/../diffs/single/test_1_new.png')
    , diffFilePath = path.join(__dirname + '/../diffs/single/test_1_diff.png');

var test = function () {
    var img_good = new Canvas.Image()
            , img_new = new Canvas.Image()
            , img_good_data = null
            , img_new_data = null
            , tolerance = 10
            , equal = false
            , diff_result = null;

          fs.readFile(goodFilePath, function (err, squid_good) {
              if (err) throw err;  
              img_good.src = squid_good; 
          }); 
          fs.readFile(newFilePath, function (err, squid_new) {
            if (err) throw err;
            img_new.src = squid_new;
          });

          img_new.onload = function () {
            // convert to image data 
              img_good_data = imagediff.toImageData(img_good);
              img_new_data = imagediff.toImageData(img_new);

              //compare and save diffences in new image file
              equal = imagediff.equal(img_good, img_new, tolerance);
              console.log('Image Good === Image New: ' + equal);
              diff_result = imagediff.diff(img_good_data, img_new_data, tolerance);
              imagediff.imageDataToPNG(diff_result, diffFilePath);
          }          
}


test();

但是，如果您注意到顶部的 require 语句，我会将实际的 imagediff.js 文件拉入我创建的 lib 文件夹中。我的问题是，当我尝试使用常规 require('imagediff') 语句时，程序会给出以下 Image 或 Canvas 预期错误：

/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/imagediff/imagediff.js:120
    context.drawImage(image, 0, 0);
            ^
TypeError: Image or Canvas expected
    at toImageDataFromImage (/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/imagediff/imagediff.js:120:13)
    at toImageData (/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/imagediff/imagediff.js:108:35)
    at Object.imagediff.toImageData (/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/imagediff/imagediff.js:365:14)
    at img_new.onload (/Users/willko/Desktop/DEBUGGING_IMGDIFF/specs/simple.js:30:45)
    at Image.inspect [as src] (/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/canvas/lib/image.js:29:17)
    at /Users/willko/Desktop/DEBUGGING_IMGDIFF/specs/simple.js:25:29
    at fs.js:266:14
    at Object.oncomplete (fs.js:107:15)

我什至尝试安装与 imagediff 使用的相同版本的画布，结果导致以下段错误错误：

/Users/willko/Desktop/DEBUGGING_IMGDIFF/node_modules/imagediff/imagediff.js:120
    context.drawImage(image, 0, 0);
            ^
[1]    34636 segmentation fault  node simple.js

我的问题：

为什么我不能将此模块与正常要求一起使用？或者为什么它使用文件路径 require 语句但否则失败？

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