From 13e1ffa04670d7c7a363d54eab92e31f01243cd7 Mon Sep 17 00:00:00 2001
From: Markus <53560412+brainbugfix@users.noreply.github.com>
Date: Thu, 8 Apr 2021 00:26:09 +0200
Subject: [PATCH] feat: add comment tag encoding (#87)

---
 index.d.ts                       |   2 +-
 lib/encoder.js                   |  17 ++++++++++++++++-
 test/fixtures/redbox_comment.jpg | Bin 0 -> 2259 bytes
 test/index.js                    |  26 ++++++++++++++++++++++++++
 4 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 test/fixtures/redbox_comment.jpg

diff --git a/index.d.ts b/index.d.ts
index 696cc7a..adbdd4b 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -10,7 +10,7 @@ type UintArrRet = RawImageData<Uint8Array>;
 type ImageData = BufferRet | UintArrRet;
 type BufferLike = Buffer | Uint8Array | ArrayLike<number> | Iterable<number> | ArrayBuffer;
 
-export declare function encode(imgData: RawImageData<BufferLike>, quality?: number): BufferRet;
+export declare function encode(imgData: RawImageData<BufferLike> & {comments?: string[]}, quality?: number): BufferRet
 
 export declare function decode(
   jpegData: BufferLike,
diff --git a/lib/encoder.js b/lib/encoder.js
index bb17d3b..fdbc184 100644
--- a/lib/encoder.js
+++ b/lib/encoder.js
@@ -535,6 +535,20 @@ function JPEGEncoder(quality) {
 				writeByte(std_ac_chrominance_values[p]);
 			}
 		}
+		
+		function writeCOM(comments)
+		{
+			if (typeof comments === "undefined" || comments.constructor !== Array) return;
+			comments.forEach(e => {
+				if (typeof e !== "string") return;
+				writeWord(0xFFFE); // marker
+				var l = e.length;
+				writeWord(l + 2); // length itself as well
+				var i;
+				for (i = 0; i < l; i++)
+					writeByte(e.charCodeAt(i));
+			});
+		}
 	
 		function writeSOS()
 		{
@@ -625,6 +639,7 @@ function JPEGEncoder(quality) {
 			// Add JPEG headers
 			writeWord(0xFFD8); // SOI
 			writeAPP0();
+			writeCOM(image.comments);
 			writeAPP1(image.exifBuffer);
 			writeDQT();
 			writeSOF0(image.width,image.height);
@@ -782,7 +797,7 @@ function encode(imgData, qu) {
   return {
     data: data,
     width: imgData.width,
-    height: imgData.height
+    height: imgData.height,
   };
 }
 
diff --git a/test/fixtures/redbox_comment.jpg b/test/fixtures/redbox_comment.jpg
new file mode 100644
index 0000000000000000000000000000000000000000..a0c4235df179f608851127b5637ff590bda64e0e
GIT binary patch
literal 2259
zcmex=<NpH&0WUXCHwH#V1_nkTWcdG&f!{5&sJKKSIX^cyHLnCHAP}6IoS&Bh7rD*Q
z!XUuS!^guVz{krcBq$&(p&=z9CMIF1tSYNvWo&C>X>4Kc;1T2J;1cd?ZV`|h7#^RL
zo{?_nTUc3;QW2Ayp3EpHBqSj!p)Vz+pX_AeluR=Ce}F-dgJBD!12dx_1Ct;lvmoRD
zBaDlH-e6?}0|qEyWMXDvWn<^y<l+`!U}9uuW@2GxWo2Ojs;mXdF|Y`-3Mm>ovIz$!
zvMUve7&T5@$f4}C@t|nX#SbdRNkvVZTw>x9l2WQ_>Kd9_CZ=ZQ7M51dF0O9w9-dyo
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z7#Wx$-T{&j4<Y#n=y66S78Yg}c94G<naY8fS&)TQ(U48ZF_1m6P*};Rkwe63;=+vw
zIhBorK8Pk2UE~r|F?p!^5#%MXkBIY76InijdkF5I|F;-;m>Gc)#w^HS&v10T&hG;Y
hm>RekG#Eyy(I6O21)~{Zv@94c4#}z!{xkf)2>`3X8TSAH

literal 0
HcmV?d00001

diff --git a/test/index.js b/test/index.js
index 6944449..fd1339a 100644
--- a/test/index.js
+++ b/test/index.js
@@ -179,6 +179,32 @@ it('should be able to create a JPEG from an array', function () {
   expect(jpegImageData.data).toEqual(expected);
 });
 
+it('should be able to create a JPEG from an array with comment', function () {
+  var width = 320,
+    height = 180;
+  var comments = ["First comment", "Second comment"];
+  var frameData = new Buffer(width * height * 4);
+  var i = 0;
+  while (i < frameData.length) {
+    frameData[i++] = 0xff; // red
+    frameData[i++] = 0x00; // green
+    frameData[i++] = 0x00; // blue
+    frameData[i++] = 0xff; // alpha - ignored in JPEGs
+  }
+  var rawImageData = {
+    data: frameData,
+    width: width,
+    height: height,
+    comments: comments,
+  };
+  var jpegImageData = jpeg.encode(rawImageData, 50); 
+  expect(jpegImageData.width).toEqual(width);
+  expect(jpegImageData.height).toEqual(height);
+  var expected = fixture('redbox_comment.jpg');
+  expect(jpegImageData.data).toEqual(expected);
+  expect(jpeg.decode(jpegImageData.data).comments).toEqual(['First comment', 'Second comment']);
+});
+
 it('should be able to decode a JPEG into a typed array', function () {
   var jpegData = fixture('grumpycat.jpg');
   var rawImageData = jpeg.decode(jpegData, {useTArray: true});