libwebp: update to 0.4.2-rc2

third_party/libwebp/enc/webpenc.c

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // WebP encoder: main entry point
@@ skipping 310 matching lines @@
     return WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_DIMENSION);
   if (pic->width > WEBP_MAX_DIMENSION || pic->height > WEBP_MAX_DIMENSION)
     return WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_DIMENSION);
 
   if (pic->stats != NULL) memset(pic->stats, 0, sizeof(*pic->stats));
 
   if (!config->lossless) {
     VP8Encoder* enc = NULL;
     if (pic->y == NULL || pic->u == NULL || pic->v == NULL) {
       // Make sure we have YUVA samples.
-      float dithering = 0.f;
-      if (config->preprocessing & 2) {
-        const float x = config->quality / 100.f;
-        const float x2 = x * x;
-        // slowly decreasing from max dithering at low quality (q->0)
-        // to 0.5 dithering amplitude at high quality (q->100)
-        dithering = 1.0f + (0.5f - 1.0f) * x2 * x2;
-      }
-      if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) {
-        return 0;
+      if (config->preprocessing & 4) {
+#if WEBP_ENCODER_ABI_VERSION > 0x0204
+        if (!WebPPictureSmartARGBToYUVA(pic)) {
+          return 0;
+        }
+#endif
+      } else {
+        float dithering = 0.f;
+        if (config->preprocessing & 2) {
+          const float x = config->quality / 100.f;
+          const float x2 = x * x;
+          // slowly decreasing from max dithering at low quality (q->0)
+          // to 0.5 dithering amplitude at high quality (q->100)
+          dithering = 1.0f + (0.5f - 1.0f) * x2 * x2;
+        }
+        if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) {
+          return 0;
+        }
       }
     }
 
     enc = InitVP8Encoder(config, pic);
     if (enc == NULL) return 0;  // pic->error is already set.
     // Note: each of the tasks below account for 20% in the progress report.
     ok = VP8EncAnalyze(enc);
 
     // Analysis is done, proceed to actual coding.
     ok = ok && VP8EncStartAlpha(enc);   // possibly done in parallel
@@ skipping 14 matching lines @@
     // Make sure we have ARGB samples.
     if (pic->argb == NULL && !WebPPictureYUVAToARGB(pic)) {
       return 0;
     }
 
     ok = VP8LEncodeImage(config, pic);  // Sets pic->error in case of problem.
   }
 
   return ok;
 }