Bug 869723 (Part 3) - Parse EXIF orientation in nsJPEGDecoder. r=joe

image/decoders/nsJPEGDecoder.cpp

@@ -6,6 +6,8 @@
 
 #include "ImageLogging.h"
 #include "nsJPEGDecoder.h"
+#include "Orientation.h"
+#include "EXIF.h"
 
 #include "nsIInputStream.h"
 
@@ -235,7 +237,7 @@ nsJPEGDecoder::WriteInternal(const char *aBuffer, uint32_t aCount)
     }
 
     // Post our size to the superclass
-    PostSize(mInfo.image_width, mInfo.image_height);
+    PostSize(mInfo.image_width, mInfo.image_height, ReadOrientationFromEXIF());
     if (HasError()) {
       // Setting the size led to an error.
       mState = JPEG_ERROR;
@@ -533,6 +535,27 @@ nsJPEGDecoder::WriteInternal(const char *aBuffer, uint32_t aCount)
   return;
 }
 
+Orientation
+nsJPEGDecoder::ReadOrientationFromEXIF()
+{
+  jpeg_saved_marker_ptr marker;
+
+  // Locate the APP1 marker, where EXIF data is stored, in the marker list.
+  for (marker = mInfo.marker_list ; marker != nullptr ; marker = marker->next) {
+    if (marker->marker == JPEG_APP0 + 1) 
+      break;
+  }
+
+  // If we're at the end of the list, there's no EXIF data.
+  if (!marker)
+    return Orientation();
+
+  // Extract the orientation information.
+  EXIFData exif = EXIFParser::Parse(marker->data,
+                                    static_cast<uint32_t>(marker->data_length));
+  return exif.orientation;
+}
+
 void
 nsJPEGDecoder::NotifyDone()
 {

image/decoders/nsJPEGDecoder.h

@@ -47,6 +47,7 @@ typedef enum {
 } jstate;
 
 class RasterImage;
+class Orientation;
 
 class nsJPEGDecoder : public Decoder
 {
@@ -62,6 +63,7 @@ public:
   void NotifyDone();
 
 protected:
+  Orientation ReadOrientationFromEXIF();
   void OutputScanlines(bool* suspend);
 
 public: