Question

我想将image1像素的一半替换为image2像素的前一半

var bodyParser = require('body-parser'),
    express = require('express');

var app = express(); 

 var image1 = "./img1.jpg";
 var image2 = "./img2.jpg";

  app.get("/",function(req,res){

  });


  app.listen(process.env.PORT || 3000, function() {
    console.log('server is runing');
});

有没有办法遍历并获取image1像素并将其替换？

Answer 1

假定两个图像的大小相同。您可以使用PureImage来实现。通过利用drawImage，您可以控制要将图像绘制到其他图像上的位置。 drawImage的工作方式与html5-canvas相同，并且可以最好地满足您的要求，因为您可以剪切图像并将该图像部分放置到另一图像的任何区域上。

此示例创建并返回一个新图像，其中包含image2的上半部分和image1的下半部分：

let bodyParser = require('body-parser'),
    express = require('express'),
    PImage = require('pureimage'),
    fs = require('fs'),
    app = express();

let image1 = "./img1.jpg";
let image2 = "./img2.jpg";

app.get("/", (req,res) => {
    PImage.decodeJPEGFromStream(fs.createReadStream(image1)).then((image1) => {
        // create newImage based on the size of image1
        let newImage = PImage.make(image1.width,image1.height);
        // get drawing context of newImage
        let c = newImage.getContext('2d');
        // 1. draw image1 on the whole canvas 1:1
        c.drawImage(image1,
            0, 0, image1.width, image1.height
        );
        PImage.decodeJPEGFromStream(fs.createReadStream(image2)).then((image2) => {
            // 2. draw only upper half of image2 onto newImage
            c.drawImage(image2,
                0, 0, image2.width, image2.height/2, // get only upper half of image2 -> sourceX, sourceY, sourceWidth, sourceHeight 
                0, 0, newImage.width, newImage.height/2 // draw upper half of image2 onto upper half of newImage -> destinationX, destinationY, destinationWidth, destinationHeight 
            );
            // 3. save newImage on filesystem and return it to client afterwards
            let pth = __dirname+"/newImage.jpg";
            PImage.encodeJPEGToStream(newImage,fs.createWriteStream(pth)).then(() => {
                console.log("done writing");
                res.sendFile(pth);
            });
        });

    });
});

app.listen(process.env.PORT || 3000, ()  => console.log('server is runing'));

如何替换节点JS中的图像像素

1 个答案: