libwebp: update to 0.5.0

This commit imports libwebp 0.5.0, including AUTHORS, COPYING, ChangeLog,
NEWS, PATENTS, README and src directories. In src, only includes header
and source files.

The patches required to build it in Qt will follow in separate
commit(s).

Change-Id: I96b4961ba63c75cc7fbab158c36a0f403f254c14
Reviewed-by: aavit <eirik.aavitsland@theqtcompany.com>

1 files changed, 160 insertions, 0 deletions

diff --git a/src/3rdparty/libwebp/src/enc/near_lossless.c b/src/3rdparty/libwebp/src/enc/near_lossless.c
new file mode 100644
index 0000000..9bc0f0e
--- /dev/null
+++ b/src/3rdparty/libwebp/src/enc/near_lossless.c
@@ -0,0 +1,160 @@
+// Copyright 2014 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.
+// -----------------------------------------------------------------------------
+//
+// Near-lossless image preprocessing adjusts pixel values to help
+// compressibility with a guarantee of maximum deviation between original and
+// resulting pixel values.
+//
+// Author: Jyrki Alakuijala (jyrki@google.com)
+// Converted to C by Aleksander Kramarz (akramarz@google.com)
+
+#include <stdlib.h>
+
+#include "../dsp/lossless.h"
+#include "../utils/utils.h"
+#include "./vp8enci.h"
+
+#define MIN_DIM_FOR_NEAR_LOSSLESS 64
+#define MAX_LIMIT_BITS             5
+
+// Computes quantized pixel value and distance from original value.
+static void GetValAndDistance(int a, int initial, int bits,
+                              int* const val, int* const distance) {
+  const int mask = ~((1 << bits) - 1);
+  *val = (initial & mask) | (initial >> (8 - bits));
+  *distance = 2 * abs(a - *val);
+}
+
+// Clamps the value to range [0, 255].
+static int Clamp8b(int val) {
+  const int min_val = 0;
+  const int max_val = 0xff;
+  return (val < min_val) ? min_val : (val > max_val) ? max_val : val;
+}
+
+// Quantizes values {a, a+(1<<bits), a-(1<<bits)} and returns the nearest one.
+static int FindClosestDiscretized(int a, int bits) {
+  int best_val = a, i;
+  int min_distance = 256;
+
+  for (i = -1; i <= 1; ++i) {
+    int candidate, distance;
+    const int val = Clamp8b(a + i * (1 << bits));
+    GetValAndDistance(a, val, bits, &candidate, &distance);
+    if (i != 0) {
+      ++distance;
+    }
+    // Smallest distance but favor i == 0 over i == -1 and i == 1
+    // since that keeps the overall intensity more constant in the
+    // images.
+    if (distance < min_distance) {
+      min_distance = distance;
+      best_val = candidate;
+    }
+  }
+  return best_val;
+}
+
+// Applies FindClosestDiscretized to all channels of pixel.
+static uint32_t ClosestDiscretizedArgb(uint32_t a, int bits) {
+  return
+      (FindClosestDiscretized(a >> 24, bits) << 24) |
+      (FindClosestDiscretized((a >> 16) & 0xff, bits) << 16) |
+      (FindClosestDiscretized((a >> 8) & 0xff, bits) << 8) |
+      (FindClosestDiscretized(a & 0xff, bits));
+}
+
+// Checks if distance between corresponding channel values of pixels a and b
+// is within the given limit.
+static int IsNear(uint32_t a, uint32_t b, int limit) {
+  int k;
+  for (k = 0; k < 4; ++k) {
+    const int delta =
+        (int)((a >> (k * 8)) & 0xff) - (int)((b >> (k * 8)) & 0xff);
+    if (delta >= limit || delta <= -limit) {
+      return 0;
+    }
+  }
+  return 1;
+}
+
+static int IsSmooth(const uint32_t* const prev_row,
+                    const uint32_t* const curr_row,
+                    const uint32_t* const next_row,
+                    int ix, int limit) {
+  // Check that all pixels in 4-connected neighborhood are smooth.
+  return (IsNear(curr_row[ix], curr_row[ix - 1], limit) &&
+          IsNear(curr_row[ix], curr_row[ix + 1], limit) &&
+          IsNear(curr_row[ix], prev_row[ix], limit) &&
+          IsNear(curr_row[ix], next_row[ix], limit));
+}
+
+// Adjusts pixel values of image with given maximum error.
+static void NearLossless(int xsize, int ysize, uint32_t* argb,
+                         int limit_bits, uint32_t* copy_buffer) {
+  int x, y;
+  const int limit = 1 << limit_bits;
+  uint32_t* prev_row = copy_buffer;
+  uint32_t* curr_row = prev_row + xsize;
+  uint32_t* next_row = curr_row + xsize;
+  memcpy(copy_buffer, argb, xsize * 2 * sizeof(argb[0]));
+
+  for (y = 1; y < ysize - 1; ++y) {
+    uint32_t* const curr_argb_row = argb + y * xsize;
+    uint32_t* const next_argb_row = curr_argb_row + xsize;
+    memcpy(next_row, next_argb_row, xsize * sizeof(argb[0]));
+    for (x = 1; x < xsize - 1; ++x) {
+      if (!IsSmooth(prev_row, curr_row, next_row, x, limit)) {
+        curr_argb_row[x] = ClosestDiscretizedArgb(curr_row[x], limit_bits);
+      }
+    }
+    {
+      // Three-way swap.
+      uint32_t* const temp = prev_row;
+      prev_row = curr_row;
+      curr_row = next_row;
+      next_row = temp;
+    }
+  }
+}
+
+static int QualityToLimitBits(int quality) {
+  // quality mapping:
+  //  0..19 -> 5
+  //  0..39 -> 4
+  //  0..59 -> 3
+  //  0..79 -> 2
+  //  0..99 -> 1
+  //  100   -> 0
+  return MAX_LIMIT_BITS - quality / 20;
+}
+
+int VP8ApplyNearLossless(int xsize, int ysize, uint32_t* argb, int quality) {
+  int i;
+  uint32_t* const copy_buffer =
+      (uint32_t*)WebPSafeMalloc(xsize * 3, sizeof(*copy_buffer));
+  const int limit_bits = QualityToLimitBits(quality);
+  assert(argb != NULL);
+  assert(limit_bits >= 0);
+  assert(limit_bits <= MAX_LIMIT_BITS);
+  if (copy_buffer == NULL) {
+    return 0;
+  }
+  // For small icon images, don't attempt to apply near-lossless compression.
+  if (xsize < MIN_DIM_FOR_NEAR_LOSSLESS && ysize < MIN_DIM_FOR_NEAR_LOSSLESS) {
+    WebPSafeFree(copy_buffer);
+    return 1;
+  }
+
+  for (i = limit_bits; i != 0; --i) {
+    NearLossless(xsize, ysize, argb, i, copy_buffer);
+  }
+  WebPSafeFree(copy_buffer);
+  return 1;
+}