Revert of Delete SkImageDecoder

src/images/SkJpegUtility.cpp

Index: src/images/SkJpegUtility.cpp
diff --git a/src/images/SkJpegUtility.cpp b/src/images/SkJpegUtility.cpp
index ab8486bcf6261fc40476ec23714bfd6e6f939089..f1a32cae1007fa101f53353d8474cd9e709de079 100644
--- a/src/images/SkJpegUtility.cpp
+++ b/src/images/SkJpegUtility.cpp
@@ -7,6 +7,108 @@
 
 
 #include "SkJpegUtility.h"
+
+/////////////////////////////////////////////////////////////////////
+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_JPEG_INDEX_SUPPORTED
+    src->current_offset = 0;
+#endif
+    if (!src->fStream->rewind()) {
+        SkDebugf("xxxxxxxxxxxxxx failure to rewind\n");
+        cinfo->err->error_exit((j_common_ptr)cinfo);
+    }
+}
+
+#ifdef SK_JPEG_INDEX_SUPPORTED
+static boolean sk_seek_input_data(j_decompress_ptr cinfo, long byte_offset) {
+    skjpeg_source_mgr* src = (skjpeg_source_mgr*)cinfo->src;
+    size_t bo = (size_t) byte_offset;
+
+    if (bo > src->current_offset) {
+        (void)src->fStream->skip(bo - src->current_offset);
+    } else {
+        if (!src->fStream->rewind()) {
+            SkDebugf("xxxxxxxxxxxxxx failure to rewind\n");
+            cinfo->err->error_exit((j_common_ptr)cinfo);
+            return false;
+        }
+        (void)src->fStream->skip(bo);
+    }
+
+    src->current_offset = bo;
+    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 != nullptr && src->fDecoder->shouldCancelDecode()) {
+        return FALSE;
+    }
+    size_t bytes = src->fStream->read(src->fBuffer, skjpeg_source_mgr::kBufferSize);
+    // note that JPEG is happy with less than the full read,
+    // as long as the result is non-zero
+    if (bytes == 0) {
+        return FALSE;
+    }
+
+#ifdef SK_JPEG_INDEX_SUPPORTED
+    src->current_offset += bytes;
+#endif
+    src->next_input_byte = (const JOCTET*)src->fBuffer;
+    src->bytes_in_buffer = bytes;
+    return TRUE;
+}
+
+static void sk_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
+    skjpeg_source_mgr*  src = (skjpeg_source_mgr*)cinfo->src;
+
+    if (num_bytes > (long)src->bytes_in_buffer) {
+        size_t bytesToSkip = num_bytes - src->bytes_in_buffer;
+        while (bytesToSkip > 0) {
+            size_t bytes = src->fStream->skip(bytesToSkip);
+            if (bytes <= 0 || bytes > bytesToSkip) {
+//              SkDebugf("xxxxxxxxxxxxxx failure to skip request %d returned %d\n", bytesToSkip, bytes);
+                cinfo->err->error_exit((j_common_ptr)cinfo);
+                return;
+            }
+#ifdef SK_JPEG_INDEX_SUPPORTED
+            src->current_offset += bytes;
+#endif
+            bytesToSkip -= bytes;
+        }
+        src->next_input_byte = (const JOCTET*)src->fBuffer;
+        src->bytes_in_buffer = 0;
+    } else {
+        src->next_input_byte += num_bytes;
+        src->bytes_in_buffer -= num_bytes;
+    }
+}
+
+static void sk_term_source(j_decompress_ptr /*cinfo*/) {}
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+skjpeg_source_mgr::skjpeg_source_mgr(SkStream* stream, SkImageDecoder* decoder)
+    : fStream(stream)
+    , fDecoder(decoder) {
+
+    init_source = sk_init_source;
+    fill_input_buffer = sk_fill_input_buffer;
+    skip_input_data = sk_skip_input_data;
+    resync_to_restart = jpeg_resync_to_restart;
+    term_source = sk_term_source;
+#ifdef SK_JPEG_INDEX_SUPPORTED
+    seek_input_data = sk_seek_input_data;
+#endif
+//    SkDebugf("**************** use memorybase %p %d\n", fMemoryBase, fMemoryBaseSize);
+}
 
 ///////////////////////////////////////////////////////////////////////////////