Question

这是以下服务器端版本：

http://jsfiddle.net/mowglisanu/frhwm2xe/3/

虽然主逻辑应该不变（跟踪消息和数据结构更改除外），但它不能多次处理文件。

因此我怀疑原始版本中存在错误，但原始小提琴让文件第二次未经处理。

./ exifrm.js

/**
    remove: GPS Information, Camera Info, etc..
    <code>
        var f = fs.readFileSync('exif.jpg')
        fs.writeFileSync('exifclean.jpg', remove(f))
    </code>
    @arg {Buffer} imageArrayBuffer image/jpeg
    @return {Buffer} image/jpeg
*/
function remove(imageArrayBuffer) {
    if(!Buffer.isBuffer(imageArrayBuffer))
        throw new TypeError('Expecting Buffer for parameter: imageArrayBuffer')

    if(!imageArrayBuffer.buffer)
        throw new TypeError('Expecting Buffer to contain ArrayBuffer property: imageArrayBuffer.buffer (check node version)')

    const pieces = [];
    const dv = new DataView(imageArrayBuffer.buffer);
    let offset = 0, recess = 0;
    let i = 0;

    // jpeg magic bytes 0xffd8
    console.log('dv.getUint16(offset) == 0xffd8', dv.getUint16(offset) == 0xffd8)
    if (dv.getUint16(offset) == 0xffd8){
        offset += 2;
        let app1 = dv.getUint16(offset);
        offset += 2;
        console.log('offset < dv.byteLength', offset < dv.byteLength)
        while (offset < dv.byteLength){
            if (app1 == 0xffe1){
                console.log('app1 == 0xffe1', app1 == 0xffe1)
                pieces[i] = {recess: recess, offset: offset -  2};
                recess = offset + dv.getUint16(offset);
                i++;
            }
            else if (app1 == 0xffda){
                console.log('app1 == 0xffda', app1 == 0xffda)
                break;
            }
            offset += dv.getUint16(offset);
            app1 = dv.getUint16(offset);
            offset += 2;
        }
        console.log('pieces.length > 0', pieces.length > 0)
        if (pieces.length > 0){
            const newPieces = [];
            pieces.forEach(function(v){
                newPieces.push(imageArrayBuffer.slice(v.recess, v.offset));
            }, this);
            newPieces.push(imageArrayBuffer.slice(recess));
            return Buffer.concat(newPieces)
        }
    }
}

module.exports = {remove}

测试如下。将上面的代码保存为exifrm.js，然后运行：

wget http://www.suodenjoki.dk/images/news/2008/water.jpg

node
> var f1, f2
> var exif = require('./exifrm.js')

> f1 = exif.remove(fs.readFileSync('./water.jpg'))
dv.getUint16(offset) == 0xffd8 true
offset < dv.byteLength true
app1 == 0xffe1 true
app1 == 0xffe1 true
app1 == 0xffda true
pieces.length > 0 true
<Buffer ff d8 ff e0 00 10 4a 46 49 46 00 01 02 01 00 f0 00 f0 00 00 ff ed 21 82 50 68 6f 74 6f 73 68 6f 70 20 33 2e 30 00 38 42 49 4d 04 04 00 00 00 00 00 35 ... >

> f2 = exif.remove(f1)
dv.getUint16(offset) == 0xffd8 true
offset < dv.byteLength true
app1 == 0xffda true
pieces.length > 0 false
undefined

预期输出为f2.length === 57817。

从图像中剥离EXIF数据（node-js，解决原始版本中可能存在的错误）

0 个答案: