Prepares support for uncompressed thumbnails.

Bug: 26894354

src/piex.cc

@@ -90,6 +90,8 @@ void GetThumbnailOffsetAndLength(const TagSet& extended_tags,
   PreviewImageData thumbnail_data;
   if (GetPreviewData(desired_tags, kNumberOfIfds, stream, &thumbnail_data) ==
       kOk) {
+    preview_image_data->thumbnail = thumbnail_data.preview;
+    // TODO: remove the old vars.
     preview_image_data->thumbnail_offset = thumbnail_data.preview_offset;
     preview_image_data->thumbnail_length = thumbnail_data.preview_length;
   }
@@ -121,17 +123,6 @@ Error GetExifIfd(const Endian endian, StreamInterface* stream,
                         stream, exif_ifd, &next_ifd_offset);
 }
 
-struct Image {
-  std::uint16_t width = 0;
-  std::uint16_t height = 0;
-  std::uint32_t length = 0;
-  std::uint32_t offset = 0;
-
-  bool operator>(const Image& rhs) const {
-    return width > rhs.width && height > rhs.height;
-  }
-};
-
 bool IsThumbnail(const Image& image) {
   // According to Tiff/EP a thumbnail has max 256 pixels per dimension.
   // http://standardsproposals.bsigroup.com/Home/getPDF/567
@@ -256,10 +247,13 @@ Error GetOlympusPreviewImage(StreamInterface* stream,
   if (makernote_ifd.Has(kThumbnailTag)) {
     if (!makernote_ifd.GetOffsetAndLength(
             kThumbnailTag, tiff_directory::TIFF_TYPE_UNDEFINED,
-            &preview_image_data->thumbnail_offset,
-            &preview_image_data->thumbnail_length)) {
+            &preview_image_data->thumbnail.offset,
+            &preview_image_data->thumbnail.length)) {
       return kFail;
     }
+    // TODO: remove the old vars.
+    preview_image_data->thumbnail_offset = preview_image_data->thumbnail.offset;
+    preview_image_data->thumbnail_length = preview_image_data->thumbnail.length;
   }
 
   TiffDirectory camera_settings_ifd(endian);
@@ -276,9 +270,12 @@ Error GetOlympusPreviewImage(StreamInterface* stream,
     return kUnsupported;
   }
 
-  camera_settings_ifd.Get(kPreviewOffset, &preview_image_data->preview_offset);
-  preview_image_data->preview_offset += makernote_offset;
-  camera_settings_ifd.Get(kPreviewLength, &preview_image_data->preview_length);
+  camera_settings_ifd.Get(kPreviewOffset, &preview_image_data->preview.offset);
+  preview_image_data->preview.offset += makernote_offset;
+  camera_settings_ifd.Get(kPreviewLength, &preview_image_data->preview.length);
+  // TODO: remove the old vars.
+  preview_image_data->preview_offset = preview_image_data->preview.offset;
+  preview_image_data->preview_length = preview_image_data->preview.length;
 
   // Get the crop size from the raw processing ifd.
   TiffDirectory raw_processing_ifd(endian);
@@ -443,7 +440,9 @@ Error DngGetPreviewData(StreamInterface* stream,
       }
     }
   }
-
+  preview_image_data->preview = preview;
+  preview_image_data->thumbnail = thumbnail;
+  // TODO: remove the old vars.
   preview_image_data->preview_length = preview.length;
   preview_image_data->preview_offset = preview.offset;
   preview_image_data->thumbnail_length = thumbnail.length;
@@ -466,6 +465,8 @@ Error NefGetPreviewData(StreamInterface* stream,
 
   PreviewImageData thumbnail_data;
   GetThumbnailOffsetAndLength(TagSet(), stream, &thumbnail_data);
+  preview_image_data->thumbnail = thumbnail_data.thumbnail;
+  // TODO: remove the old vars.
   preview_image_data->thumbnail_offset = thumbnail_data.thumbnail_offset;
   preview_image_data->thumbnail_length = thumbnail_data.thumbnail_length;
 
@@ -530,6 +531,8 @@ Error PefGetPreviewData(StreamInterface* stream,
 
   PreviewImageData thumbnail_data;
   GetThumbnailOffsetAndLength(TagSet(), stream, &thumbnail_data);
+  preview_image_data->thumbnail = thumbnail_data.thumbnail;
+  // TODO: remove the old vars.
   preview_image_data->thumbnail_offset = thumbnail_data.thumbnail_offset;
   preview_image_data->thumbnail_length = thumbnail_data.thumbnail_length;
 
@@ -565,11 +568,15 @@ Error RafGetPreviewData(StreamInterface* stream,
   // Merge the Exif data with the RAW data to form the preview_image_data.
   // The preview offset and length extracted from the Exif data are actually
   // the thumbnail offset and length.
-  preview_image_data->thumbnail_offset = preview_image_data->preview_offset;
-  preview_image_data->thumbnail_offset += 160;  // Skip the cfa header.
-  preview_image_data->thumbnail_length = preview_image_data->preview_length;
-  preview_image_data->preview_offset = preview_offset;
-  preview_image_data->preview_length = preview_length;
+  preview_image_data->thumbnail = preview_image_data->preview;
+  preview_image_data->thumbnail.offset += 160;  // Skip the cfa header.
+  preview_image_data->preview.offset = preview_offset;
+  preview_image_data->preview.length = preview_length;
+  // TODO: remove the old vars.
+  preview_image_data->thumbnail_offset = preview_image_data->thumbnail.offset;
+  preview_image_data->thumbnail_length = preview_image_data->thumbnail.length;
+  preview_image_data->preview_offset = preview_image_data->preview.offset;
+  preview_image_data->preview_length = preview_image_data->preview.length;
   return kOk;
 }
 
@@ -598,17 +605,21 @@ Error Rw2GetPreviewData(StreamInterface* stream,
     }
     // The preview offset and length extracted from the Exif data are actually
     // the thumbnail offset and length.
-    preview_image_data->thumbnail_offset =
-        exif_offset + preview_image_data->preview_offset;
-    preview_image_data->thumbnail_length = preview_image_data->preview_length;
+    preview_image_data->thumbnail = preview_image_data->preview;
+    preview_image_data->thumbnail.offset += exif_offset;
+    // TODO: remove old vars.
+    preview_image_data->thumbnail_offset = preview_image_data->thumbnail.offset;
+    preview_image_data->thumbnail_length = preview_image_data->thumbnail.length;
   }
 
   // Merge the Exif data with the RAW data to form the preview_image_data.
-  preview_image_data->preview_offset = preview_data.preview_offset;
-  preview_image_data->preview_length = preview_data.preview_length;
+  preview_image_data->preview = preview_data.preview;
   preview_image_data->iso = preview_data.iso;
   preview_image_data->full_width = preview_data.full_width;
   preview_image_data->full_height = preview_data.full_height;
+  // TODO: remove old vars.
+  preview_image_data->preview_offset = preview_image_data->preview.offset;
+  preview_image_data->preview_length = preview_image_data->preview.length;
 
   return kOk;
 }

src/piex_types.h

@@ -30,6 +30,25 @@ enum Error {
   kUnsupported,
 };
 
+// Defines the properties of an image. width and height are required for
+// uncompressed images, but are optional for compressed images. An image is
+// invalid when its length is 0.
+struct Image {
+  enum Format {
+    kJpegCompressed,
+  };
+
+  std::uint16_t width = 0;
+  std::uint16_t height = 0;
+  std::uint32_t length = 0;
+  std::uint32_t offset = 0;
+  Format format = kJpegCompressed;
+
+  bool operator>(const Image& rhs) const {
+    return width > rhs.width && height > rhs.height;
+  }
+};
+
 // Contains relevant image information as well as the 'preview_offset' and the
 // 'preview_length' which are used to obtain the JPEG compressed preview image.
 // 'full_width' and 'full_height' are correctly cropped but not rotated.
@@ -61,10 +80,15 @@ struct PreviewImageData {
   // correctly. A thumbnail is typically 160x120 pixel small and usually
   // has black borders at the top and bottom. If length is 0 the image could not
   // be extracted.
+  // Note: Deprecate the offset, length versions. Use these Image structs
+  // instead.
   std::uint32_t preview_offset = 0;
   std::uint32_t preview_length = 0;
   std::uint32_t thumbnail_offset = 0;
   std::uint32_t thumbnail_length = 0;
+  Image preview;
+  Image thumbnail;
+
   std::uint32_t exif_orientation = 1;  // horizontal as default
   ColorSpace color_space = kSrgb;
 

src/tiff_parser.cc

@@ -173,22 +173,32 @@ Error FillPreviewImageData(const TiffDirectory& tiff_directory,
       return kFail;
     }
     if (strip_offsets.size() == 1 && strip_byte_counts.size() == 1) {
+      preview_image_data->preview.offset = strip_offsets[0];
+      preview_image_data->preview.length = strip_byte_counts[0];
+      // TODO: remove old vars.
       preview_image_data->preview_offset = strip_offsets[0];
       preview_image_data->preview_length = strip_byte_counts[0];
     }
   } else if (tiff_directory.Has(kTiffTagJpegOffset) &&
              tiff_directory.Has(kTiffTagJpegByteCount)) {
     success &= tiff_directory.Get(kTiffTagJpegOffset,
-                                  &preview_image_data->preview_offset);
+                                  &preview_image_data->preview.offset);
     success &= tiff_directory.Get(kTiffTagJpegByteCount,
-                                  &preview_image_data->preview_length);
+                                  &preview_image_data->preview.length);
+    // TODO: remove old vars.
+    preview_image_data->preview_offset = preview_image_data->preview.offset;
+    preview_image_data->preview_length = preview_image_data->preview.length;
+
   } else if (tiff_directory.Has(kPanaTagJpegImage)) {
     if (!tiff_directory.GetOffsetAndLength(
             kPanaTagJpegImage, TIFF_TYPE_UNDEFINED,
-            &preview_image_data->preview_offset,
-            &preview_image_data->preview_length)) {
+            &preview_image_data->preview.offset,
+            &preview_image_data->preview.length)) {
       return kFail;
     }
+    // TODO: remove old vars.
+    preview_image_data->preview_offset = preview_image_data->preview.offset;
+    preview_image_data->preview_length = preview_image_data->preview.length;
   }
 
   // Get exif_orientation if it was not set already.