如何在Node.js中将二进制缓冲区保存到PNG文件？ [英] How to save binary buffer to png file in nodejs?

问题描述

我有二进制的nodejs Buffer对象，其中包含位图信息。如何从缓冲区制作图像并将其保存到文件？

I have binary nodejs Buffer object that contains bitmap information. How do make image from the buffer and save it to file?

编辑：

我尝试使用文件系统软件包，如@herchu所说，但如果我这样做：

I tried using the file system package as @herchu said but if I do this:

let robot = require("robotjs")
let fs = require('fs')

let size = 200
let img = robot.screen.capture(0, 0, size, size)


let path = 'myfile.png'
let buffer = img.image

fs.open(path, 'w', function (err, fd) {
  if (err) {
    // Something wrong creating the file
  }

  fs.write(fd, buffer, 0, buffer.length, null, function (err) {
    // Something wrong writing contents!
  })
})

我得到

推荐答案

注意：我正在根据您最近的修改来编辑我的答案

如果您使用的是Robotjs，请检查其位图对象包含用于原始像素数据的缓冲区-不是PNG或任何其他文件格式的内容，只是彼此相邻的像素（在您的情况下为200 x 200元素）。

If you are using Robotjs, check that its Bitmap object contains a Buffer to raw pixels data -- not a PNG or any other file format contents, just pixels next to each other (exactly 200 x 200 elements in your case).

我没有在Robotjs库中找到任何以其他格式写入内容的函数（也不是我也知道），因此在此答案中，我使用的是另一个库 Jimp ，用于图像处理。

I have not found any function to write contents in other format in the Robotjs library (not that I know it either), so in this answer I am using a different library, Jimp, for the image manipulation.

let robot = require("robotjs")
let fs = require('fs')
let Jimp = require('jimp')

let size = 200
let rimg = robot.screen.capture(0, 0, size, size)
let path = 'myfile.png'

// Create a new blank image, same size as Robotjs' one
let jimg = new Jimp(size, size);
for (var x=0; x<size; x++) {
        for (var y=0; y<size; y++) {
                // hex is a string, rrggbb format
                var hex = rimg.colorAt(x, y);
                // Jimp expects an Int, with RGBA data,
                // so add FF as 'full opaque' to RGB color
                var num = parseInt(hex+"ff", 16)
                // Set pixel manually
                jimg.setPixelColor(num, x, y);
        }
    }
jimg.write(path)

注意通过手动遍历所有像素来完成转换；这在JS中很慢。另外，还有关于每个库如何处理其像素格式的一些详细信息，因此循环中需要进行一些操作-从嵌入的注释中应该很清楚。

Note that the conversion is done by manually iterating through all pixels; this is slow in JS. Also there are some details on how each library handles their pixel format, so some manipulation was needed in the loop -- it should be clear from the embedded comments.

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