Upstream changes from Android for decoding jpeg images.

src/images/SkJpegUtility.cpp

Index: src/images/SkJpegUtility.cpp
diff --git a/src/images/SkJpegUtility.cpp b/src/images/SkJpegUtility.cpp
index 19db0186d27fd392f9c58605b9d6d4f127de88f1..89a0472380b444118e422e28ee2e9aaea8c5d891 100644
--- a/src/images/SkJpegUtility.cpp
+++ b/src/images/SkJpegUtility.cpp
@@ -9,14 +9,41 @@
 
 #include "SkJpegUtility.h"
 
+// Uncomment to enable the code path used by the Android framework with their
+// custom image decoders.
+//#if defined(SK_BUILD_FOR_ANDROID) && defined(SK_DEBUG)
+//  #define SK_BUILD_FOR_ANDROID_FRAMEWORK
+//#endif
+
 /////////////////////////////////////////////////////////////////////
 static void sk_init_source(j_decompress_ptr cinfo) {
     skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
     src->next_input_byte = (const JOCTET*)src->fBuffer;
     src->bytes_in_buffer = 0;
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    src->current_offset = 0;
+#endif
     src->fStream->rewind();
 }
 
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+static boolean sk_seek_input_data(j_decompress_ptr cinfo, long byte_offset) {
+    skjpeg_source_mgr* src = (skjpeg_source_mgr*)cinfo->src;
+
+    if (byte_offset > src->current_offset) {
+        (void)src->fStream->skip(byte_offset - src->current_offset);
+    } else {
+        src->fStream->rewind();
+        (void)src->fStream->skip(byte_offset);
+    }
+
+    src->current_offset = byte_offset;
+    src->next_input_byte = (const JOCTET*)src->fBuffer;
+    src->bytes_in_buffer = 0;
+    return true;
+}
+#endif
+
 static boolean sk_fill_input_buffer(j_decompress_ptr cinfo) {
     skjpeg_source_mgr* src = (skjpeg_source_mgr*)cinfo->src;
     if (src->fDecoder != NULL && src->fDecoder->shouldCancelDecode()) {
@@ -29,6 +56,9 @@ static boolean sk_fill_input_buffer(j_decompress_ptr cinfo) {
         return FALSE;
     }
 
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    src->current_offset += bytes;
+#endif
     src->next_input_byte = (const JOCTET*)src->fBuffer;
     src->bytes_in_buffer = bytes;
     return TRUE;
@@ -46,6 +76,9 @@ static void sk_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
                 cinfo->err->error_exit((j_common_ptr)cinfo);
                 return;
             }
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+            src->current_offset += bytes;
+#endif
             bytesToSkip -= bytes;
         }
         src->next_input_byte = (const JOCTET*)src->fBuffer;
@@ -74,40 +107,11 @@ static boolean sk_resync_to_restart(j_decompress_ptr cinfo, int desired) {
 static void sk_term_source(j_decompress_ptr /*cinfo*/) {}
 
 
-#if 0 // UNUSED
-static void skmem_init_source(j_decompress_ptr cinfo) {
-    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
-    src->next_input_byte = (const JOCTET*)src->fMemoryBase;
-    src->bytes_in_buffer = src->fMemoryBaseSize;
-}
-
-static boolean skmem_fill_input_buffer(j_decompress_ptr cinfo) {
-    SkDebugf("xxxxxxxxxxxxxx skmem_fill_input_buffer called\n");
-    return FALSE;
-}
-
-static void skmem_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
-    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
-//    SkDebugf("xxxxxxxxxxxxxx skmem_skip_input_data called %d\n", num_bytes);
-    src->next_input_byte = (const JOCTET*)((const char*)src->next_input_byte + num_bytes);
-    src->bytes_in_buffer -= num_bytes;
-}
-
-static boolean skmem_resync_to_restart(j_decompress_ptr cinfo, int desired) {
-    SkDebugf("xxxxxxxxxxxxxx skmem_resync_to_restart called\n");
-    return TRUE;
-}
-
-static void skmem_term_source(j_decompress_ptr /*cinfo*/) {}
-#endif
-
-
 ///////////////////////////////////////////////////////////////////////////////
 
 skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream, SkImageDecoder* decoder,
                                      bool ownStream) : fStream(stream) {
     fDecoder = decoder;
-    // const void* baseAddr = stream->getMemoryBase();
     fMemoryBase = NULL;
     fUnrefStream = ownStream;
     fMemoryBaseSize = 0;
@@ -117,6 +121,9 @@ skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream, SkImageDecoder* decoder,
     skip_input_data = sk_skip_input_data;
     resync_to_restart = sk_resync_to_restart;
     term_source = sk_term_source;
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    seek_input_data = sk_seek_input_data;
+#endif
 //    SkDebugf("**************** use memorybase %p %d\n", fMemoryBase, fMemoryBaseSize);
 }