From ae1c046e120350b92e366a421289a060b7711fc2 Mon Sep 17 00:00:00 2001
From: Urvang Joshi <urvang@google.com>
Date: Tue, 6 Jan 2015 16:22:29 -0800
Subject: [PATCH] AnimEncoder lib cleanup: prev to prev canvas not needed.

Given that we decided to only handle frame disposal for output WebP
internally,
only current and previous canvas need to be maintained.

Change-Id: I625293bed5aeb5aabf4eca779f6ec3ee84c9ff2a
---
 src/mux/anim_encode.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/src/mux/anim_encode.c b/src/mux/anim_encode.c
index b192ee59..79ebc9a2 100644
--- a/src/mux/anim_encode.c
+++ b/src/mux/anim_encode.c
@@ -46,7 +46,6 @@ struct WebPAnimEncoder {
   WebPPicture curr_canvas_mod_;       // Possibly modified current canvas.
   WebPPicture prev_canvas_;           // Previous canvas.
   WebPPicture prev_canvas_disposed_;  // Previous canvas disposed to background.
-  WebPPicture prev_to_prev_canvas_;   // Previous to previous canvas.
 
   // Encoded data.
   EncodedFrame* encoded_frames_;      // Array of encoded frames.
@@ -204,8 +203,7 @@ WebPAnimEncoder* WebPAnimEncoderNewInternal(
   // Canvas buffers.
   if (!WebPPictureInit(&enc->curr_canvas_mod_) ||
       !WebPPictureInit(&enc->prev_canvas_) ||
-      !WebPPictureInit(&enc->prev_canvas_disposed_) ||
-      !WebPPictureInit(&enc->prev_to_prev_canvas_)) {
+      !WebPPictureInit(&enc->prev_canvas_disposed_)) {
     return NULL;
   }
   enc->curr_canvas_mod_.width = width;
@@ -213,12 +211,10 @@ WebPAnimEncoder* WebPAnimEncoderNewInternal(
   enc->curr_canvas_mod_.use_argb = 1;
   if (!WebPPictureAlloc(&enc->curr_canvas_mod_) ||
       !WebPPictureCopy(&enc->curr_canvas_mod_, &enc->prev_canvas_) ||
-      !WebPPictureCopy(&enc->curr_canvas_mod_, &enc->prev_canvas_disposed_) ||
-      !WebPPictureCopy(&enc->curr_canvas_mod_, &enc->prev_to_prev_canvas_)) {
+      !WebPPictureCopy(&enc->curr_canvas_mod_, &enc->prev_canvas_disposed_)) {
     goto Err;
   }
   WebPUtilClearPic(&enc->prev_canvas_, NULL);
-  WebPUtilClearPic(&enc->prev_to_prev_canvas_, NULL);
 
   // Encoded frames.
   ResetCounters(enc);
@@ -256,7 +252,6 @@ void WebPAnimEncoderDelete(WebPAnimEncoder* enc) {
     WebPPictureFree(&enc->curr_canvas_mod_);
     WebPPictureFree(&enc->prev_canvas_);
     WebPPictureFree(&enc->prev_canvas_disposed_);
-    WebPPictureFree(&enc->prev_to_prev_canvas_);
     if (enc->encoded_frames_ != NULL) {
       size_t i;
       for (i = 0; i < enc->size_; ++i) {
@@ -966,7 +961,6 @@ static int CacheFrame(WebPAnimEncoder* const enc, int duration,
   }
 
   // Update previous to previous and previous canvases for next call.
-  CopyPixels(&enc->prev_canvas_, &enc->prev_to_prev_canvas_);
   CopyPixels(enc->curr_canvas_, &enc->prev_canvas_);
   enc->is_first_frame_ = 0;
   ok = 1;