將2個stdin參數傳遞給ImageMagick child_process

Question

我有一些限制，我不會指定要求我將ImageMagick用作子進程。

我有多個base64字符串的jpg文件，我希望ImageMagick處理。 具體而言，我希望ImageMagick一起加入jpg文件。如果我有2個普通的jpg文件，然後從命令行我會使用以下格式。

node convert in_1.jpg in_2.jpg +append out.jpg 

在js文件

我會用

var spawn, magicCommands, imagic; 
spawn = require('child_process').spawn; 
magicCommands = ["in_1.jpg", 
       "in_2.jpg", 
       "+append", 
       "out.jpg"]; 
imagic = spawn("convert", magicCommands); 

現在，如果我想用標準輸入緩衝區以下將工作

var arrow1JpgBase64, arrow2JpgBase64, arrowBuffer1, arrowBuffer2, magicCommands, imagic; 

    spawn = require('child_process').spawn; 
    exec = require('child_process').exec; 

    arrow1JpgBase64 = "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"; 
    arrow2JpgBase64 = "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"; 
    arrowBuffer1 = new Buffer(arrow1JpgBase64, 'base64'); 
    arrowBuffer2 = new Buffer(arrow2JpgBase64, 'base64'); 
    magicCommands = ["jpg:", 
        "in_2.jpg", 
        "+append", 
        "out.jpg"]; 

    imagic = spawn("convert", magicCommands); 
    imagic.stdin.write(arrowBuffer1); 
    imagic.stdin.end(); 

    imagic.on('exit', function (code) { 
     if (code === 0) { 
      exec("open out.jpg"); 
     } else { 
      console.log("error code: " + code); 
     } 
    }); // end of on exit 

到目前爲止好，但我想要使用這兩個的緩衝區，而不僅僅是它們的。所以如果我用行替換那麼我該如何改變腳本的其餘部分才能使其工作？

感謝

Answer 1

不能確定什麼這些「限制」是，或者我們要設法避免或解決的，但數據流將多個文件合併成一個的下列技術可幫助您：

# Make a red block 
convert -size 50x50 xc:red multi.miff 

# Make a green block, but APPEND INTO A SINGLE STREAM 
convert -size 50x50 xc:lime miff:- >> multi.miff 

# Make a blue block, but APPEND INTO A SINGLE STREAM 
convert -size 50x50 xc:blue miff:- >> multi.miff 

# Tell IM to convert and append multiple images in single stream 
convert multi.miff +append result.png 

另外，如果你改變上面下面的最後一個命令，IM將盡快刪除該文件multi.miff，因爲它已經完成了它 - 即爲您整理！

convert ephemeral:multi.miff +append result.png 

Answer 2

正如馬克·瑟特查在評論中指出，使用ImageMagick的fd:協議會工作。

var spawnOptions = { 
     stdio: [ 
     0, // stdin, 
     1, // stdout 
     2, // stderr 
     'pipe', // arrowBuffer1 
     'pipe' // arrowBuffer2 
     ] 
}; 
magic = spawn("convert", magicCommands, spawnOptions); 

這將打開fd:3 & fd:4的管道。我並非是node.js家族的失敗者，但除了pipe之外，通常還有一種方法可以傳遞資源。

爲您的代碼

更新magickCommands變量從新fd的讀取，並直接寫入新pipes

magicCommands = ["fd:3", 
       "fd:4", 
       "+append", 
       "out.jpg"]; 

// ... 
imagic.stdio[3].write(arrowBuffer1); 
imagic.stdio[4].write(arrowBuffer2); 
imagic.stdio[3].end(); 
imagic.stdio[4].end();