Add flag to decoder class to flip the image vertically since that is required

on some platforms.

BUG=none
TEST=run code, verify that screen is upside-up.

Review URL: http://codereview.chromium.org/2878009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51052 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 14 insertions, 2 deletions

diff --git a/remoting/client/decoder_verbatim.cc b/remoting/client/decoder_verbatim.cc
index aba5dce..e9b88ef 100644
--- a/remoting/client/decoder_verbatim.cc
+++ b/remoting/client/decoder_verbatim.cc
@@ -9,7 +9,8 @@
 namespace remoting {
 
 DecoderVerbatim::DecoderVerbatim()
-    : updated_rects_(NULL) {
+    : updated_rects_(NULL),
+      reverse_rows_(true) {
 }
 
 bool DecoderVerbatim::BeginDecode(scoped_refptr<media::VideoFrame> frame,
@@ -51,13 +52,20 @@ bool DecoderVerbatim::PartialDecode(HostMessage* message) {
   // Copy the data line by line.
   const int src_stride = bytes_per_pixel * width;
   const char* src = message->update_stream_packet().data().c_str();
+  int src_stride_dir = src_stride;
+  if (reverse_rows_) {
+    // Copy rows from bottom to top to flip the image vertically.
+    src += (height - 1) * src_stride;
+    // Change the direction of the stride to work bottom to top.
+    src_stride_dir *= -1;
+  }
   const int dest_stride = frame_->stride(media::VideoFrame::kRGBPlane);
   uint8* dest = frame_->data(media::VideoFrame::kRGBPlane) +
       dest_stride * y + bytes_per_pixel * x;
   for (int i = 0; i < height; ++i) {
     memcpy(dest, src, src_stride);
     dest += dest_stride;
-    src += src_stride;
+    src += src_stride_dir;
   }
 
   updated_rects_->clear();
diff --git a/remoting/client/decoder_verbatim.h b/remoting/client/decoder_verbatim.h
index b1f776c..85b49c6 100644
--- a/remoting/client/decoder_verbatim.h
+++ b/remoting/client/decoder_verbatim.h
@@ -30,6 +30,10 @@ class DecoderVerbatim : public Decoder {
   scoped_refptr<media::VideoFrame> frame_;
   UpdatedRects* updated_rects_;
 
+  // True if we should reverse the rows when copying data into the target
+  // frame buffer.
+  bool reverse_rows_;
+
   DISALLOW_COPY_AND_ASSIGN(DecoderVerbatim);
 };