Change exif encoder to copy fields of original image.

This CL also changes to set compression tag and update software name tag.

BUG=437142
TEST=out/Release/browser_tests --gtest_filter=GalleryJsTest.ExifEncoderTest

Review URL: https://codereview.chromium.org/831333005

Cr-Commit-Position: refs/heads/master@{#310234}

4 files changed, 80 insertions, 14 deletions

diff --git a/ui/file_manager/file_manager/foreground/js/metadata/exif_constants.js b/ui/file_manager/file_manager/foreground/js/metadata/exif_constants.js
index 3df514d..bb23871 100644
--- a/ui/file_manager/file_manager/foreground/js/metadata/exif_constants.js
+++ b/ui/file_manager/file_manager/foreground/js/metadata/exif_constants.js
@@ -51,7 +51,9 @@ Exif.Tag = {
   JPG_THUMB_LENGTH: 0x0202,
   IMAGE_WIDTH: 0x0100,
   IMAGE_HEIGHT: 0x0101,
+  COMPRESSION: 0x0102,
   ORIENTATION: 0x0112,
   X_DIMENSION: 0xA002,
-  Y_DIMENSION: 0xA003
+  Y_DIMENSION: 0xA003,
+  SOFTWARE: 0x0131,
 };
diff --git a/ui/file_manager/gallery/js/image_editor/exif_encoder.js b/ui/file_manager/gallery/js/image_editor/exif_encoder.js
index 70a91a4..1ddebbe 100644
--- a/ui/file_manager/gallery/js/image_editor/exif_encoder.js
+++ b/ui/file_manager/gallery/js/image_editor/exif_encoder.js
@@ -5,17 +5,18 @@
 /**
  * The Exif metadata encoder.
  * Uses the metadata format as defined by ExifParser.
- * @param {!Object} original_metadata Metadata to encode.
+ * @param {!Object} originalMetadata Metadata to encode.
  * @constructor
  * @extends {ImageEncoder.MetadataEncoder}
  * @struct
  */
-function ExifEncoder(original_metadata) {
+function ExifEncoder(originalMetadata) {
   ImageEncoder.MetadataEncoder.apply(this, arguments);
 
-  this.ifd_ = this.metadata_.ifd;
-  if (!this.ifd_)
-    this.ifd_ = this.metadata_.ifd = {};
+  if (this.metadata_.media && this.metadata_.media.ifd)
+    this.ifd_ = this.metadata_.media.ifd;
+  else
+    this.ifd_ = {};
 }
 
 ExifEncoder.prototype = {__proto__: ImageEncoder.MetadataEncoder.prototype};
@@ -23,6 +24,13 @@ ExifEncoder.prototype = {__proto__: ImageEncoder.MetadataEncoder.prototype};
 ImageEncoder.registerMetadataEncoder(ExifEncoder, 'image/jpeg');
 
 /**
+ * Software name of Gallery.app.
+ * @type {string}
+ * @const
+ */
+ExifEncoder.SOFTWARE = 'Chrome OS Gallery App\0';
+
+/**
  * @override
  */
 ExifEncoder.prototype.setImageData = function(canvas) {
@@ -49,8 +57,12 @@ ExifEncoder.prototype.setImageData = function(canvas) {
   // Always save in default orientation.
   delete this.metadata_['imageTransform'];
   ExifEncoder.findOrCreateTag(image, Exif.Tag.ORIENTATION).value = 1;
-};
 
+  // Update software name.
+  var softwareTag = ExifEncoder.findOrCreateTag(image, Exif.Tag.SOFTWARE, 2);
+  softwareTag.value = ExifEncoder.SOFTWARE;
+  softwareTag.componentCount = ExifEncoder.SOFTWARE.length;
+};
 
 /**
  * @override
@@ -90,6 +102,10 @@ ExifEncoder.prototype.setThumbnailData = function(canvas, quality) {
 
     // Always save in default orientation.
     ExifEncoder.findOrCreateTag(thumbnail, Exif.Tag.ORIENTATION).value = 1;
+
+    // When thumbnail is compressed with JPEG, compression must be set as 6.
+    ExifEncoder.findOrCreateTag(this.ifd_.image, Exif.Tag.COMPRESSION).value =
+        6;
   } else {
     console.warn(
         'Thumbnail URL too long: ' + this.metadata_.thumbnailURL.length);
@@ -331,10 +347,14 @@ ExifEncoder.getComponentWidth = function(tag) {
  */
 ExifEncoder.writeValue = function(bw, tag) {
   if (tag.format === 2) {  // String
-    if (tag.componentCount != tag.value.length) {
+    if (tag.componentCount !== tag.value.length) {
       throw new Error(
           'String size mismatch for 0x' + Number(tag.id).toString(16));
     }
+
+    if (tag.value.charAt(tag.value.length - 1) !== '\0')
+      throw new Error('String must end with null character.');
+
     bw.writeString(/** @type {string} */ (tag.value));
   } else {  // Scalar or rational
     var width = ExifEncoder.getComponentWidth(tag);
diff --git a/ui/file_manager/gallery/js/image_editor/exif_encoder_unittest.js b/ui/file_manager/gallery/js/image_editor/exif_encoder_unittest.js
index 4afd939..95f5893 100644
--- a/ui/file_manager/gallery/js/image_editor/exif_encoder_unittest.js
+++ b/ui/file_manager/gallery/js/image_editor/exif_encoder_unittest.js
@@ -20,14 +20,39 @@ function testExifEncodeAndDecode() {
             id: 0x10f,
             format: 2,
             componentCount: 12,
-            value: 'Manufacture'
+            value: 'Manufacture\0'
           },
           // Device model
           272: {
             id: 0x110,
             format: 2,
             componentCount: 12,
-            value: 'DeviceModel'
+            value: 'DeviceModel\0'
+          },
+          // GPS Pointer
+          34853: {
+            id: 0x8825,
+            format: 4,
+            componentCount: 1,
+            value: 0 // The value is set by the encoder.
+          }
+        },
+        exif: {
+          // Lens model
+          42036: {
+            id: 0xa434,
+            format: 2,
+            componentCount: 10,
+            value: 'LensModel\0'
+          }
+        },
+        gps: {
+          // GPS latitude ref
+          1: {
+            id: 0x1,
+            format: 2,
+            componentCount: 2,
+            value: 'N\0'
           }
         }
       }
@@ -56,14 +81,29 @@ function testExifEncodeAndDecode() {
   // Check ifd.image.
   assertEquals(1, parsedMetadata.ifd.image[0x112].value); // Orientation
 
+  // Since thumbnail is compressed with JPEG, compression must be 6.
+  assertEquals(6, parsedMetadata.ifd.image[0x102].value);
+
   // Check ifd.exif.
   assertEquals(1920, parsedMetadata.ifd.exif[0xA002].value); // PixelXDimension
   assertEquals(1080, parsedMetadata.ifd.exif[0xA003].value); // PixelYDimension
 
-  // TODO(yawano) Change exif_encoder to preserve these fields.
-  // These fileds are not encoded.
-  assertEquals(undefined, parsedMetadata.ifd.image[0x10F]); // Manufacture
-  assertEquals(undefined, parsedMetadata.ifd.image[0x110]); // Device model
+  // These fields should be copied correctly.
+  // Manufacture
+  assertEquals('Manufacture\0', parsedMetadata.ifd.image[0x10F].value);
+  // Device model
+  assertEquals('DeviceModel\0', parsedMetadata.ifd.image[0x110].value);
+  // Lens model
+  assertEquals('LensModel\0', parsedMetadata.ifd.exif[0xa434].value);
+  // GPS latitude ref
+  assertEquals('N\0', parsedMetadata.ifd.gps[0x1].value);
+
+  // Software should be set as Gallery.app
+  assertEquals('Chrome OS Gallery App\0',
+      parsedMetadata.ifd.image[0x131].value);
+
+  // TODO(yawano): Datetime should be updated.
+  assertEquals(undefined, parsedMetadata.ifd.image[0x132]); // Datetime
 
   // Thumbnail image
   assert(parsedMetadata.thumbnailTransform);
diff --git a/ui/file_manager/gallery/js/image_editor/image_encoder.js b/ui/file_manager/gallery/js/image_editor/image_encoder.js
index 7b3ebf3..3c549a5 100644
--- a/ui/file_manager/gallery/js/image_editor/image_encoder.js
+++ b/ui/file_manager/gallery/js/image_editor/image_encoder.js
@@ -205,6 +205,10 @@ ImageEncoder.MetadataEncoder.getMimeType_ = function(metadata) {
 /**
  * Returns metadata.
  * @return {!Object} A metadata.
+ *
+ * TODO(yawano): MetadataEncoder.getMetadata seems not to be used anymore.
+ *     Investigate this, and remove if possible. Should not modify a metadata by
+ *     using an encoder.
  */
 ImageEncoder.MetadataEncoder.prototype.getMetadata = function() {
   return this.metadata_;