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Added LZMA compression support for SWF files #6

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f1f9c9b
added support for LZMA compressed swf-files
ankakaak Jun 13, 2015
ec9e87b
updated example in README
ankakaak Jun 13, 2015
5b9c6cb
corrected text in README
ankakaak Jun 13, 2015
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16 changes: 8 additions & 8 deletions README.md
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Expand Up @@ -2,11 +2,9 @@

This is a small package for node.js to allow the analysis of image data in a Buffer, and return mime-type, and image dimensions for the data.

It is designed to be fast, completely written in javascript and have no dependencies on external packages or libraries.
It is designed to be fast, completely written in javascript.

Currently it supports Png, Jpeg, Gif and (uncompressed) Swf analysis.

If you also have zlib available (`npm install zlib`) then it will support compressed Swf files.
Currently it supports Png, Jpeg, Gif and Swf(uncompressed, deflate and LZMA) analysis.

## Usage:

Expand All @@ -18,10 +16,12 @@ To install imageinfo into your project, use `npm install imageinfo`, then it's s
fs.readFile('testimage', function(err, data) {
if (err) throw err;

info = imageinfo(data);
console.log("Data is type:", info.mimeType);
console.log(" Size:", data.length, "bytes");
console.log(" Dimensions:", info.width, "x", info.height);
imageinfo(data, function (info) {
console.log("Data is type:", info.mimeType);
console.log("Size:", data.length, "bytes");
console.log("Dimensions:", info.width, "x", info.height);
});

});

## License:
Expand Down
116 changes: 95 additions & 21 deletions index.js
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Expand Up @@ -57,7 +57,7 @@ function readBit(buffer, offset, bitOffset) {

function readBits(buffer, offset, bitOffset, bitLen, signed) {
var val = 0;

var neg = false;
if (signed) {
if (readBit(buffer, offset, bitOffset) > 0) {
Expand Down Expand Up @@ -98,7 +98,7 @@ function imageInfoPng(buffer) {
format: 'PNG',
mimeType: 'image/png',
width: readUInt32(buffer, pos, true),
height: readUInt32(buffer, pos+4, true),
height: readUInt32(buffer, pos+4, true)
};
}

Expand All @@ -115,7 +115,7 @@ function imageInfoJpg(buffer) {
format: 'JPG',
mimeType: 'image/jpeg',
width: readUInt16(buffer, pos+2, true),
height: readUInt16(buffer, pos, true),
height: readUInt16(buffer, pos, true)
};
}

Expand All @@ -133,36 +133,100 @@ function imageInfoGif(buffer) {
format: 'GIF',
mimeType: 'image/gif',
width: readUInt16(buffer, pos, false),
height: readUInt16(buffer, pos+2, false),
height: readUInt16(buffer, pos+2, false)
};
}

function imageInfoSwf(buffer) {
var pos = 8,
/**
* Found advice for SWF 2 7Z LZMA-Header conversion:
* https://helpx.adobe.com/flash-player/kb/exception-thrown-you-decompress-lzma-compressed.html
*
* @param buffer swf-lzma formated
* @return buffer 7z-lzma formated
*/
function convertSwfTo7zLzmaHeader(buffer) {

var scriptlen = buffer[4] & 0xFF | (buffer[5] & 0xFF) << 8 | (buffer[6] & 0xFF) << 16 | buffer[7] << 24;
scriptlen -= 8;

var lzmaProperties = buffer.slice(12, 17);

var headerUnCompressedSize = new Buffer([scriptlen & 0xFF, (scriptlen >> 8) & 0xFF, (scriptlen >> 16) & 0xFF, (scriptlen >> 24) & 0xFF, 0, 0, 0, 0 ]);

var newHeader = Buffer.concat([ lzmaProperties, headerUnCompressedSize ]);

var sevenZipLZMAFormatedData = Buffer.concat([newHeader, buffer.slice(17)]);

return sevenZipLZMAFormatedData;
}


function imageInfoSwf(buffer, cb, p, extraInfo) {

var pos = p > -1 ? p : 8,
bitPos = 0,
val;

if (!extraInfo) {
extraInfo = {
flashVersion: buffer[3],
isCompressed: buffer[0] === 0x43 || buffer[0] === 0x5a,
uncompressedSize: buffer[4] & 0xFF | (buffer[5] & 0xFF) << 8 | (buffer[6] & 0xFF) << 16 | buffer[7] << 24
}
}

if (buffer[0] === 0x43) {
try {
// If you have zlib available ( npm install zlib ) then we can read compressed flash files
buffer = require('zlib').inflate(buffer.slice(8, 100));
pos = 0;
require('zlib').inflate(buffer.slice(8), function (error, buffer) {
imageInfoSwf(buffer, cb, 0, extraInfo);
});

return;
}
catch (ex) {
// Can't get width/height of compressed flash files... yet (need zlib)
return {
type: 'flash',
format: 'SWF',
mimeType: 'application/x-shockwave-flash',
version: extraInfo ? extraInfo.flashVersion : null,
isCompressed: extraInfo ? extraInfo.isCompressed : null,
uncompressedSize: extraInfo ? extraInfo.uncompressedSize : null,
width: null,
height: null,
height: null
}
}
}
} else if (buffer[0] === 0x5a) {

//swf file is lzma compressed

try {
var lzmaBuffer = convertSwfTo7zLzmaHeader(buffer);

require("lzma").decompress(lzmaBuffer, function(uncompressedBuffer) {
imageInfoSwf(uncompressedBuffer, cb, 0, extraInfo);
});
return;
}
catch (ex) {
return {
type: 'flash',
format: 'SWF',
mimeType: 'application/x-shockwave-flash',
version: extraInfo ? extraInfo.flashVersion : null,
isCompressed: extraInfo ? extraInfo.isCompressed : null,
uncompressedSize: extraInfo ? extraInfo.uncompressedSize : null,
width: null,
height: null
}
}

}

var numBits = readBits(buffer, pos, bitPos, 5)[0];
bitPos += 5;

val = readBits(buffer, pos, bitPos, numBits, true);
var xMin = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);
bitPos += numBits;
Expand All @@ -178,13 +242,23 @@ function imageInfoSwf(buffer) {
val = readBits(buffer, pos, bitPos, numBits, true);
var yMax = (numBits > 9 ? readUInt16(val, 0, true) : val[0]) * (val.negative ? -1 : 1);

return {
var byteIdx = 9;
var fps = readUInt16(buffer, byteIdx, false) / 256;
byteIdx += 2;
var frameCount = readUInt16(buffer, byteIdx, false);

cb({
type: 'flash',
format: 'SWF',
mimeType: 'application/x-shockwave-flash',
version: extraInfo ? extraInfo.flashVersion : null,
isCompressed: extraInfo ? extraInfo.isCompressed : null,
uncompressedSize: extraInfo ? extraInfo.uncompressedSize : null,
fps: fps,
frameCount: frameCount,
width: Math.ceil((xMax - xMin) / 20),
height: Math.ceil((yMax - yMin) / 20),
};
height: Math.ceil((yMax - yMin) / 20)
});
}

function checkSig(buffer, offset, sig) {
Expand Down Expand Up @@ -214,17 +288,17 @@ function checkSig(buffer, offset, sig) {
return true;
}

module.exports = function imageInfo(buffer, path) {
module.exports = function imageInfo(buffer, cb) {
var pngSig = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
var jpgSig = [0xff, 0xd8, 0xff];
var gifSig = [0x47, 0x49, 0x46, 0x38, [0x37, 0x39], 0x61];
var swfSig = [[0x46, 0x43], 0x57, 0x53];
var swfSig = [[0x46, 0x43, 0x5a], 0x57, 0x53];

if (checkSig(buffer, 0, pngSig)) return imageInfoPng(buffer);
if (checkSig(buffer, 0, jpgSig)) return imageInfoJpg(buffer);
if (checkSig(buffer, 0, gifSig)) return imageInfoGif(buffer);
if (checkSig(buffer, 0, swfSig)) return imageInfoSwf(buffer);
if (checkSig(buffer, 0, pngSig)) cb(imageInfoPng(buffer));
else if (checkSig(buffer, 0, jpgSig)) cb(imageInfoJpg(buffer));
else if (checkSig(buffer, 0, gifSig)) cb(imageInfoGif(buffer));
else if (checkSig(buffer, 0, swfSig)) imageInfoSwf(buffer, cb);
else cb({});

return false;
};

8 changes: 5 additions & 3 deletions package.json
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Expand Up @@ -2,7 +2,7 @@
"name": "imageinfo",
"description": "A node.js package that returns information about an image or flash file such as type, dimensions etc.",
"homepage": "https://github.com/NorgannasAddOns/node-imageinfo",
"version": "1.0.4",
"version": "1.1.0",
"author": "Norganna <ken@norganna.com>",
"repository": {
"type": "git",
Expand All @@ -13,12 +13,14 @@
},
"main": "index",
"keywords": [
"image", "info", "jpg", "jpeg", "png", "gif", "swf", "dimensions", "size", "type", "mime", "format"
"image", "info", "jpg", "jpeg", "png", "gif", "swf", "dimensions", "size", "type", "mime", "format", "lzma"
],
"engines": {
"node": ">=0.4"
},
"dependencies": {},
"dependencies": {
"lzma": "2.1.5"
},
"devDependencies": {},
"directories": {
"lib": ".",
Expand Down