如何将图像缓冲区数据传递给（）GraphicsMagic中的gm

var buf = require('fs').readFileSync('test.jpg');

gm().in('-page', '+0+0').in(buf,'test.jpg').write('output.jpg', function (err) {
     if (err) console.log(err);
})

in this case i want to pass buffer data as input to the gm.in() method.

在这种情况下，我想将缓冲区数据作为输入传递给gm.in（）方法。

Below is the link I'm referencing but in it, an image path is used as an input. I want to use buffer data as an input. How can I do this?

下面是我正在引用的链接，但在其中，图像路径用作输入。我想使用缓冲区数据作为输入。我怎样才能做到这一点？

Tile four images together using Node.js and GraphicsMagick

使用Node.js和GraphicsMagick将四个图像拼接在一起

3 个解决方案

#1

Actually I was creating a poster with two different image one is template image "background" and 2nd is top image with some text. I tried with gm but i loose image quality. Someone guide me to use Buffer data as input to improve the image quality. I tried but don't know how to pass Buffer data as an input. So finally i decided to use node child process with command string. Here is the sample code i am sharing with you.

实际上我正在创建一个有两个不同图像的海报，一个是模板图像“背景”，第二个是带有一些文本的顶部图像。我试过gm但是我的图像质量很差。有人指导我使用缓冲数据作为输入来提高图像质量。我试过但不知道如何将Buffer数据作为输入传递。所以最后我决定使用带有命令字符串的node子进程。以下是我与您分享的示例代码。

var fs = require('fs');

var gm = require("gm");
var exec = require('child_process').exec;
var IMAGEFILEPATH = "/images";
var gmcreateImage = function() {

var imageConfig = {"topimage":{"density":"300x300","startx":925,"starty":650,"width":575,"height":825},
 "offers": [
          {"startx": 75, "starty": 850, "msg": "SAVE 5$", "textcolor": "#4f61ac", "font": "Arial Bold", "fontsize":34,"stroke":{"color":"#4f61ac","width":4}},
          {"startx": 75, "starty": 970, "msg": "per gallon", "textcolor": "#4f61ac", "font": "Arial Bold", "fontsize":34,"stroke":{"color":"#4f61ac","width":4}},
          {"startx": 75, "starty": 1150, "msg": "With the purchase of", "textcolor": "black", "font": "Arial", "fontsize":18,"stroke":{"color":"black","width":1}},
          {"startx": 75, "starty": 1260, "msg": "any Pepsi Z0 S2", "textcolor": "black", "font": "Arial", "fontsize":16,"stroke":{"color":"black","width":1}},
          {"startx": 75, "starty": 1370, "msg": "on all flavours", "textcolor": "black", "font": "Arial", "fontsize":16,"stroke":{"color":"black","width":1}},
          {"startx": 75, "starty": 1480, "msg": "Ask for details.", "textcolor": "black", "font": "Arial", "fontsize":18,"stroke":{"color":"black","width":1}}
]};
    var addLast=imageConfig.topimage.last;
    var commandStr = "gm convert '-page' '+0+0' '-units' 'PixelsPerInch' '-density' '" + imageConfig.topimage.density + "' '" + IMAGEFILEPATH+ "/template.jpg' ";

    var imageActualPosition={};
    imageActualPosition["x"] = imageConfig.topimage.startx;
    imageActualPosition["y"] = imageConfig.topimage.starty;

    if (!addLast) {
        commandStr += " '-page' '+" + imageActualPosition["x"] + "+" + imageActualPosition["y"] + "' '" + IMAGEFILEPATH + "/top.jpg' ";
    }

    var offers = imageConfig.offers;
    for (var i in offers) {
        var color = offers[i].textcolor;
        var startX = offers[i].startx;
        var startY = offers[i].starty;
        var font = offers[i].font;
        var fontSize = offers[i].fontsize;
        var msg = offers[i].msg;
        var offerStr = "";
        if (offers[i].stroke) {
            offerStr += " '-stroke' '" + offers[i].stroke.color + "' '-strokewidth' '" + offers[i].stroke.width + "'";
        }
        offerStr += " '-fill' '" + color + "' '-pointsize' '" + fontSize + "' '-draw' 'text " + startX + " " + startY + " \"" + msg + "\"'";
        commandStr += offerStr;
    }
    if (addLast) {
        commandStr += " '-page' '+" + imageActualPosition["x"] + "+" + imageActualPosition["y"] + "' '" + IMAGEFILEPATH + "/top.jpg' ";
    }
    var finalImage="done.jpg";
    commandStr += " '-mosaic' '-quality' '100' '" + IMAGEFILEPATH + finalImage + "'";
    exec(commandStr, function(err, stdout, stderr) {
            if (err) {
                console.log("Error while executing gm commands" + err);
                return;
            } else {
                console.log("Done See your image");
            }
    })
};
gmcreateImage();

#2

Without modifying the source of GraphicsMagick itself, you can't. The gm module interacts with the GraphicsMagick program through the command line. The arguments you're passing through the .in() method are being converted into command-line arguments. The GraphicsMagick program only accepts filenames for this argument and will not attempt to process any direct form of data.

如果不修改GraphicsMagick本身的来源，你就不能。 gm模块通过命令行与GraphicsMagick程序交互。您通过.in（）方法传递的参数将被转换为命令行参数。 GraphicsMagick程序只接受此参数的文件名，不会尝试处理任何直接形式的数据。

If you really needed to make this work without the filesystem, you could always download the GraphicsMagick source code and change the CLI to accept some form of data blob instead of a URL for this argument.

如果你真的需要在没有文件系统的情况下完成这项工作，你可以随时下载GraphicsMagick源代码并更改CLI以接受某种形式的数据blob而不是此参数的URL。

#3

I haven't figured out how to do it with both an image and the watermark as buffers, but I have figured out how to keep the image as a buffer:

我还没有弄清楚如何用图像和水印作为缓冲区，但我已经想出如何将图像保持为缓冲区：

gm(imageBuffer)
    .composite('./logo_path.png')
    .geometry(geometry)
    .gravity('SouthEast')
    .dissolve(this.options.opacity)
    .toBuffer(function (err, buffer) {
      next(err, buffer, 'image/jpeg');
    });
};

Check out the code in this great library for more info.

查看这个伟大的库中的代码以获取更多信息。