Add progress hook granularity in lossless

A WebPPicture instance is necessary to call WebPReportProgress() which
sets WebPPicture::error_code so as well use WebPEncodingSetError() to
record errors too, instead of functions returning a WebPEncodingError.
However there must be one WebPPicture instance per thread, with error
codes merged at sync time. A mutex could simplify that but it is not
the objective of this change.

https://groups.google.com/a/webmproject.org/g/webp-discuss/c/yOiP8APubgc/m/vCTvxl6ODgAJ

Change-Id: Ia1a8f9d1199202e1c88484ce719b0180a80447ce

src/enc/backward_references_enc.c

@@ -10,6 +10,8 @@
 // Author: Jyrki Alakuijala (jyrki@google.com)
 //
 
+#include "src/enc/backward_references_enc.h"
+
 #include <assert.h>
 #include <float.h>
 #include <math.h>
@@ -17,10 +19,11 @@
 #include "src/dsp/dsp.h"
 #include "src/dsp/lossless.h"
 #include "src/dsp/lossless_common.h"
-#include "src/enc/backward_references_enc.h"
 #include "src/enc/histogram_enc.h"
+#include "src/enc/vp8i_enc.h"
 #include "src/utils/color_cache_utils.h"
 #include "src/utils/utils.h"
+#include "src/webp/encode.h"
 
 #define MIN_BLOCK_SIZE 256  // minimum block size for backward references
 
@@ -255,10 +258,13 @@ static WEBP_INLINE int MaxFindCopyLength(int len) {
 
 int VP8LHashChainFill(VP8LHashChain* const p, int quality,
                       const uint32_t* const argb, int xsize, int ysize,
-                      int low_effort) {
+                      int low_effort, const WebPPicture* const pic,
+                      int percent_range, int* const percent) {
   const int size = xsize * ysize;
   const int iter_max = GetMaxItersForQuality(quality);
   const uint32_t window_size = GetWindowSizeForHashChain(quality, xsize);
+  int remaining_percent = percent_range;
+  int percent_start = *percent;
   int pos;
   int argb_comp;
   uint32_t base_position;
@@ -276,7 +282,13 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
 
   hash_to_first_index =
       (int32_t*)WebPSafeMalloc(HASH_SIZE, sizeof(*hash_to_first_index));
-  if (hash_to_first_index == NULL) return 0;
+  if (hash_to_first_index == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return 0;
+  }
+
+  percent_range = remaining_percent / 2;
+  remaining_percent -= percent_range;
 
   // Set the int32_t array to -1.
   memset(hash_to_first_index, 0xff, HASH_SIZE * sizeof(*hash_to_first_index));
@@ -323,12 +335,22 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
       hash_to_first_index[hash_code] = pos++;
       argb_comp = argb_comp_next;
     }
+
+    if (!WebPReportProgress(
+            pic, percent_start + percent_range * pos / (size - 2), percent)) {
+      WebPSafeFree(hash_to_first_index);
+      return 0;
+    }
   }
   // Process the penultimate pixel.
   chain[pos] = hash_to_first_index[GetPixPairHash64(argb + pos)];
 
   WebPSafeFree(hash_to_first_index);
 
+  percent_start += percent_range;
+  if (!WebPReportProgress(pic, percent_start, percent)) return 0;
+  percent_range = remaining_percent;
+
   // Find the best match interval at each pixel, defined by an offset to the
   // pixel and a length. The right-most pixel cannot match anything to the right
   // (hence a best length of 0) and the left-most pixel nothing to the left
@@ -417,8 +439,17 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
         max_base_position = base_position;
       }
     }
+
+    if (!WebPReportProgress(pic,
+                            percent_start + percent_range *
+                                                (size - 2 - base_position) /
+                                                (size - 2),
+                            percent)) {
+      return 0;
+    }
   }
-  return 1;
+
+  return WebPReportProgress(pic, percent_start + percent_range, percent);
 }
 
 static WEBP_INLINE void AddSingleLiteral(uint32_t pixel, int use_color_cache,
@@ -1006,25 +1037,31 @@ Error:
   return status;
 }
 
-WebPEncodingError VP8LGetBackwardReferences(
+int VP8LGetBackwardReferences(
     int width, int height, const uint32_t* const argb, int quality,
     int low_effort, int lz77_types_to_try, int cache_bits_max, int do_no_cache,
     const VP8LHashChain* const hash_chain, VP8LBackwardRefs* const refs,
-    int* const cache_bits_best) {
+    int* const cache_bits_best, const WebPPicture* const pic, int percent_range,
+    int* const percent) {
   if (low_effort) {
     VP8LBackwardRefs* refs_best;
     *cache_bits_best = cache_bits_max;
     refs_best = GetBackwardReferencesLowEffort(
         width, height, argb, cache_bits_best, hash_chain, refs);
-    if (refs_best == NULL) return VP8_ENC_ERROR_OUT_OF_MEMORY;
+    if (refs_best == NULL) {
+      WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+      return 0;
+    }
     // Set it in first position.
     BackwardRefsSwap(refs_best, &refs[0]);
   } else {
     if (!GetBackwardReferences(width, height, argb, quality, lz77_types_to_try,
                                cache_bits_max, do_no_cache, hash_chain, refs,
                                cache_bits_best)) {
-      return VP8_ENC_ERROR_OUT_OF_MEMORY;
+      WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+      return 0;
     }
   }
-  return VP8_ENC_OK;
+
+  return WebPReportProgress(pic, *percent + percent_range, percent);
 }