Update libwebp to 0.4.0

third_party/libwebp/dec/idec.c

Index: third_party/libwebp/dec/idec.c
diff --git a/third_party/libwebp/dec/idec.c b/third_party/libwebp/dec/idec.c
index 61635ec99c47987648a8af965c02ace9de7f4ed8..40d5ff6e0d3d855ad71ee9000b9c92260baefbe4 100644
--- a/third_party/libwebp/dec/idec.c
+++ b/third_party/libwebp/dec/idec.c
@@ -15,14 +15,11 @@
 #include <string.h>
 #include <stdlib.h>
 
+#include "./alphai.h"
 #include "./webpi.h"
 #include "./vp8i.h"
 #include "../utils/utils.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
-extern "C" {
-#endif
-
 // In append mode, buffer allocations increase as multiples of this value.
 // Needs to be a power of 2.
 #define CHUNK_SIZE 4096
@@ -31,11 +28,13 @@ extern "C" {
 //------------------------------------------------------------------------------
 // Data structures for memory and states
 
-// Decoding states. State normally flows like HEADER->PARTS0->DATA->DONE.
+// Decoding states. State normally flows as:
+// WEBP_HEADER->VP8_HEADER->VP8_PARTS0->VP8_DATA->DONE for a lossy image, and
+// WEBP_HEADER->VP8L_HEADER->VP8L_DATA->DONE for a lossless image.
 // If there is any error the decoder goes into state ERROR.
 typedef enum {
-  STATE_PRE_VP8,  // All data before that of the first VP8 chunk.
-  STATE_VP8_FRAME_HEADER,  // For VP8 Frame header (within VP8 chunk).
+  STATE_WEBP_HEADER,  // All the data before that of the VP8/VP8L chunk.
+  STATE_VP8_HEADER,   // The VP8 Frame header (within the VP8 chunk).
   STATE_VP8_PARTS0,
   STATE_VP8_DATA,
   STATE_VP8L_HEADER,
@@ -102,7 +101,7 @@ static WEBP_INLINE size_t MemDataSize(const MemBuffer* mem) {
 // Check if we need to preserve the compressed alpha data, as it may not have
 // been decoded yet.
 static int NeedCompressedAlpha(const WebPIDecoder* const idec) {
-  if (idec->state_ == STATE_PRE_VP8) {
+  if (idec->state_ == STATE_WEBP_HEADER) {
     // We haven't parsed the headers yet, so we don't know whether the image is
     // lossy or lossless. This also means that we haven't parsed the ALPH chunk.
     return 0;
@@ -111,7 +110,7 @@ static int NeedCompressedAlpha(const WebPIDecoder* const idec) {
     return 0;  // ALPH chunk is not present for lossless images.
   } else {
     const VP8Decoder* const dec = (VP8Decoder*)idec->dec_;
-    assert(dec != NULL);  // Must be true as idec->state_ != STATE_PRE_VP8.
+    assert(dec != NULL);  // Must be true as idec->state_ != STATE_WEBP_HEADER.
     return (dec->alpha_data_ != NULL) && !dec->is_alpha_decoded_;
   }
 }
@@ -141,7 +140,22 @@ static void DoRemap(WebPIDecoder* const idec, ptrdiff_t offset) {
       }
       assert(last_part >= 0);
       dec->parts_[last_part].buf_end_ = mem->buf_ + mem->end_;
-      if (NeedCompressedAlpha(idec)) dec->alpha_data_ += offset;
+      if (NeedCompressedAlpha(idec)) {
+        ALPHDecoder* const alph_dec = dec->alph_dec_;
+        dec->alpha_data_ += offset;
+        if (alph_dec != NULL) {
+          if (alph_dec->method_ == ALPHA_LOSSLESS_COMPRESSION) {
+            VP8LDecoder* const alph_vp8l_dec = alph_dec->vp8l_dec_;
+            assert(alph_vp8l_dec != NULL);
+            assert(dec->alpha_data_size_ >= ALPHA_HEADER_LEN);
+            VP8LBitReaderSetBuffer(&alph_vp8l_dec->br_,
+                                   dec->alpha_data_ + ALPHA_HEADER_LEN,
+                                   dec->alpha_data_size_ - ALPHA_HEADER_LEN);
+          } else {  // alph_dec->method_ == ALPHA_NO_COMPRESSION
+            // Nothing special to do in this case.
+          }
+        }
+      }
     } else {    // Resize lossless bitreader
       VP8LDecoder* const dec = (VP8LDecoder*)idec->dec_;
       VP8LBitReaderSetBuffer(&dec->br_, new_base, MemDataSize(mem));
@@ -268,7 +282,7 @@ static void RestoreContext(const MBContext* context, VP8Decoder* const dec,
 static VP8StatusCode IDecError(WebPIDecoder* const idec, VP8StatusCode error) {
   if (idec->state_ == STATE_VP8_DATA) {
     VP8Io* const io = &idec->io_;
-    if (io->teardown) {
+    if (io->teardown != NULL) {
       io->teardown(io);
     }
   }
@@ -311,15 +325,9 @@ static VP8StatusCode DecodeWebPHeaders(WebPIDecoder* const idec) {
       return VP8_STATUS_OUT_OF_MEMORY;
     }
     idec->dec_ = dec;
-#ifdef WEBP_USE_THREAD
-    dec->use_threads_ = (idec->params_.options != NULL) &&
-                        (idec->params_.options->use_threads > 0);
-#else
-    dec->use_threads_ = 0;
-#endif
     dec->alpha_data_ = headers.alpha_data;
     dec->alpha_data_size_ = headers.alpha_data_size;
-    ChangeState(idec, STATE_VP8_FRAME_HEADER, headers.offset);
+    ChangeState(idec, STATE_VP8_HEADER, headers.offset);
   } else {
     VP8LDecoder* const dec = VP8LNew();
     if (dec == NULL) {
@@ -334,13 +342,14 @@ static VP8StatusCode DecodeWebPHeaders(WebPIDecoder* const idec) {
 static VP8StatusCode DecodeVP8FrameHeader(WebPIDecoder* const idec) {
   const uint8_t* data = idec->mem_.buf_ + idec->mem_.start_;
   const size_t curr_size = MemDataSize(&idec->mem_);
+  int width, height;
   uint32_t bits;
 
   if (curr_size < VP8_FRAME_HEADER_SIZE) {
     // Not enough data bytes to extract VP8 Frame Header.
     return VP8_STATUS_SUSPENDED;
   }
-  if (!VP8GetInfo(data, curr_size, idec->chunk_size_, NULL, NULL)) {
+  if (!VP8GetInfo(data, curr_size, idec->chunk_size_, &width, &height)) {
     return IDecError(idec, VP8_STATUS_BITSTREAM_ERROR);
   }
 
@@ -407,7 +416,10 @@ static VP8StatusCode DecodePartition0(WebPIDecoder* const idec) {
   if (dec->status_ != VP8_STATUS_OK) {
     return IDecError(idec, dec->status_);
   }
-
+  // This change must be done before calling VP8InitFrame()
+  dec->mt_method_ = VP8GetThreadMethod(params->options, NULL,
+                                       io->width, io->height);
+  VP8InitDithering(params->options, dec);
   if (!CopyParts0Data(idec)) {
     return IDecError(idec, VP8_STATUS_OUT_OF_MEMORY);
   }
@@ -433,16 +445,11 @@ static VP8StatusCode DecodeRemaining(WebPIDecoder* const idec) {
   VP8Io* const io = &idec->io_;
 
   assert(dec->ready_);
-
   for (; dec->mb_y_ < dec->mb_h_; ++dec->mb_y_) {
     VP8BitReader* token_br = &dec->parts_[dec->mb_y_ & (dec->num_parts_ - 1)];
-    if (dec->mb_x_ == 0) {
-      VP8InitScanline(dec);
-    }
-    for (; dec->mb_x_ < dec->mb_w_;  dec->mb_x_++) {
+    for (; dec->mb_x_ < dec->mb_w_; ++dec->mb_x_) {
       MBContext context;
       SaveContext(dec, token_br, &context);
-
       if (!VP8DecodeMB(dec, token_br)) {
         RestoreContext(&context, dec, token_br);
         // We shouldn't fail when MAX_MB data was available
@@ -451,19 +458,18 @@ static VP8StatusCode DecodeRemaining(WebPIDecoder* const idec) {
         }
         return VP8_STATUS_SUSPENDED;
       }
-      // Reconstruct and emit samples.
-      VP8ReconstructBlock(dec);
-
       // Release buffer only if there is only one partition
       if (dec->num_parts_ == 1) {
         idec->mem_.start_ = token_br->buf_ - idec->mem_.buf_;
         assert(idec->mem_.start_ <= idec->mem_.end_);
       }
     }
+    VP8InitScanline(dec);   // Prepare for next scanline
+
+    // Reconstruct, filter and emit the row.
     if (!VP8ProcessRow(dec, io)) {
       return IDecError(idec, VP8_STATUS_USER_ABORT);
     }
-    dec->mb_x_ = 0;
   }
   // Synchronize the thread and check for errors.
   if (!VP8ExitCritical(dec, io)) {
@@ -475,7 +481,8 @@ static VP8StatusCode DecodeRemaining(WebPIDecoder* const idec) {
   return VP8_STATUS_OK;
 }
 
-static int ErrorStatusLossless(WebPIDecoder* const idec, VP8StatusCode status) {
+static VP8StatusCode ErrorStatusLossless(WebPIDecoder* const idec,
+                                         VP8StatusCode status) {
   if (status == VP8_STATUS_SUSPENDED || status == VP8_STATUS_NOT_ENOUGH_DATA) {
     return VP8_STATUS_SUSPENDED;
   }
@@ -532,14 +539,14 @@ static VP8StatusCode DecodeVP8LData(WebPIDecoder* const idec) {
 static VP8StatusCode IDecode(WebPIDecoder* idec) {
   VP8StatusCode status = VP8_STATUS_SUSPENDED;
 
-  if (idec->state_ == STATE_PRE_VP8) {
+  if (idec->state_ == STATE_WEBP_HEADER) {
     status = DecodeWebPHeaders(idec);
   } else {
     if (idec->dec_ == NULL) {
       return VP8_STATUS_SUSPENDED;    // can't continue if we have no decoder.
     }
   }
-  if (idec->state_ == STATE_VP8_FRAME_HEADER) {
+  if (idec->state_ == STATE_VP8_HEADER) {
     status = DecodeVP8FrameHeader(idec);
   }
   if (idec->state_ == STATE_VP8_PARTS0) {
@@ -566,7 +573,7 @@ WebPIDecoder* WebPINewDecoder(WebPDecBuffer* output_buffer) {
     return NULL;
   }
 
-  idec->state_ = STATE_PRE_VP8;
+  idec->state_ = STATE_WEBP_HEADER;
   idec->chunk_size_ = 0;
 
   InitMemBuffer(&idec->mem_);
@@ -574,7 +581,8 @@ WebPIDecoder* WebPINewDecoder(WebPDecBuffer* output_buffer) {
   VP8InitIo(&idec->io_);
 
   WebPResetDecParams(&idec->params_);
-  idec->params_.output = output_buffer ? output_buffer : &idec->output_;
+  idec->params_.output = (output_buffer != NULL) ? output_buffer
+                                                 : &idec->output_;
   WebPInitCustomIo(&idec->params_, &idec->io_);  // Plug the I/O functions.
 
   return idec;
@@ -608,11 +616,11 @@ void WebPIDelete(WebPIDecoder* idec) {
     if (!idec->is_lossless_) {
       if (idec->state_ == STATE_VP8_DATA) {
         // Synchronize the thread, clean-up and check for errors.
-        VP8ExitCritical(idec->dec_, &idec->io_);
+        VP8ExitCritical((VP8Decoder*)idec->dec_, &idec->io_);
       }
-      VP8Delete(idec->dec_);
+      VP8Delete((VP8Decoder*)idec->dec_);
     } else {
-      VP8LDelete(idec->dec_);
+      VP8LDelete((VP8LDecoder*)idec->dec_);
     }
   }
   ClearMemBuffer(&idec->mem_);
@@ -827,7 +835,7 @@ int WebPISetIOHooks(WebPIDecoder* const idec,
                     VP8IoSetupHook setup,
                     VP8IoTeardownHook teardown,
                     void* user_data) {
-  if (idec == NULL || idec->state_ > STATE_PRE_VP8) {
+  if (idec == NULL || idec->state_ > STATE_WEBP_HEADER) {
     return 0;
   }
 
@@ -839,6 +847,3 @@ int WebPISetIOHooks(WebPIDecoder* const idec,
   return 1;
 }
 
-#if defined(__cplusplus) || defined(c_plusplus)
-}    // extern "C"
-#endif