libwebp: update to v0.5.1

third_party/libwebp/utils/quant_levels_dec.c

Index: third_party/libwebp/utils/quant_levels_dec.c
diff --git a/third_party/libwebp/utils/quant_levels_dec.c b/third_party/libwebp/utils/quant_levels_dec.c
index 5b8b8b49e6bf732a86c110c344e1fbca7287c96b..ee0a3fe127d26e3fe1d41fc96949516b73a8c5e8 100644
--- a/third_party/libwebp/utils/quant_levels_dec.c
+++ b/third_party/libwebp/utils/quant_levels_dec.c
@@ -44,6 +44,7 @@ static const uint8_t kOrderedDither[DSIZE][DSIZE] = {
 
 typedef struct {
   int width_, height_;  // dimension
+  int stride_;          // stride in bytes
   int row_;             // current input row being processed
   uint8_t* src_;        // input pointer
   uint8_t* dst_;        // output pointer
@@ -99,7 +100,7 @@ static void VFilter(SmoothParams* const p) {
   // We replicate edges, as it's somewhat easier as a boundary condition.
   // That's why we don't update the 'src' pointer on top/bottom area:
   if (p->row_ >= 0 && p->row_ < p->height_ - 1) {
-    p->src_ += p->width_;
+    p->src_ += p->stride_;
   }
 }
 
@@ -149,7 +150,7 @@ static void ApplyFilter(SmoothParams* const p) {
 #endif
     }
   }
-  p->dst_ += w;  // advance output pointer
+  p->dst_ += p->stride_;  // advance output pointer
 }
 
 //------------------------------------------------------------------------------
@@ -178,17 +179,20 @@ static void InitCorrectionLUT(int16_t* const lut, int min_dist) {
   lut[0] = 0;
 }
 
-static void CountLevels(const uint8_t* const data, int size,
-                        SmoothParams* const p) {
-  int i, last_level;
+static void CountLevels(SmoothParams* const p) {
+  int i, j, last_level;
   uint8_t used_levels[256] = { 0 };
+  const uint8_t* data = p->src_;
   p->min_ = 255;
   p->max_ = 0;
-  for (i = 0; i < size; ++i) {
-    const int v = data[i];
-    if (v < p->min_) p->min_ = v;
-    if (v > p->max_) p->max_ = v;
-    used_levels[v] = 1;
+  for (j = 0; j < p->height_; ++j) {
+    for (i = 0; i < p->width_; ++i) {
+      const int v = data[i];
+      if (v < p->min_) p->min_ = v;
+      if (v > p->max_) p->max_ = v;
+      used_levels[v] = 1;
+    }
+    data += p->stride_;
   }
   // Compute the mininum distance between two non-zero levels.
   p->min_level_dist_ = p->max_ - p->min_;
@@ -208,7 +212,7 @@ static void CountLevels(const uint8_t* const data, int size,
 }
 
 // Initialize all params.
-static int InitParams(uint8_t* const data, int width, int height,
+static int InitParams(uint8_t* const data, int width, int height, int stride,
                       int radius, SmoothParams* const p) {
   const int R = 2 * radius + 1;  // total size of the kernel
 
@@ -233,6 +237,7 @@ static int InitParams(uint8_t* const data, int width, int height,
 
   p->width_ = width;
   p->height_ = height;
+  p->stride_ = stride;
   p->src_ = data;
   p->dst_ = data;
   p->radius_ = radius;
@@ -240,7 +245,7 @@ static int InitParams(uint8_t* const data, int width, int height,
   p->row_ = -radius;
 
   // analyze the input distribution so we can best-fit the threshold
-  CountLevels(data, width * height, p);
+  CountLevels(p);
 
   // correction table
   p->correction_ = ((int16_t*)mem) + LUT_SIZE;
@@ -253,7 +258,7 @@ static void CleanupParams(SmoothParams* const p) {
   WebPSafeFree(p->mem_);
 }
 
-int WebPDequantizeLevels(uint8_t* const data, int width, int height,
+int WebPDequantizeLevels(uint8_t* const data, int width, int height, int stride,
                          int strength) {
   const int radius = 4 * strength / 100;
   if (strength < 0 || strength > 100) return 0;
@@ -261,7 +266,7 @@ int WebPDequantizeLevels(uint8_t* const data, int width, int height,
   if (radius > 0) {
     SmoothParams p;
     memset(&p, 0, sizeof(p));
-    if (!InitParams(data, width, height, radius, &p)) return 0;
+    if (!InitParams(data, width, height, stride, radius, &p)) return 0;
     if (p.num_levels_ > 2) {
       for (; p.row_ < p.height_; ++p.row_) {
         VFilter(&p);  // accumulate average of input