Bundled libwebp updated to version 0.6.0

This commit imports libwebp 0.6.0, including AUTHORS, COPYING, ChangeLog,
NEWS, PATENTS, README and src directories. In src, only includes header
and source files.

Upstream changes since 0.5.1 have been merged in.
Also updated version in qt_attribution.json.

Conflicts:
	src/3rdparty/libwebp.pri
	src/3rdparty/libwebp/qt_attribution.json
	src/3rdparty/libwebp/src/webp/config.h

Change-Id: I001aa7a3fabf0130b54f9005c23aa822bc1d0ec1
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

1 files changed, 122 insertions, 0 deletions

diff --git a/src/3rdparty/libwebp/src/enc/near_lossless_enc.c b/src/3rdparty/libwebp/src/enc/near_lossless_enc.c
new file mode 100644
index 0000000..2bd03ab
--- /dev/null
+++ b/src/3rdparty/libwebp/src/enc/near_lossless_enc.c
@@ -0,0 +1,122 @@
+// 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 <assert.h>
+#include <stdlib.h>
+
+#include "../dsp/lossless_common.h"
+#include "../utils/utils.h"
+#include "./vp8i_enc.h"
+
+#define MIN_DIM_FOR_NEAR_LOSSLESS 64
+#define MAX_LIMIT_BITS             5
+
+// Quantizes the value up or down to a multiple of 1<<bits (or to 255),
+// choosing the closer one, resolving ties using bankers' rounding.
+static int FindClosestDiscretized(int a, int bits) {
+  const int mask = (1 << bits) - 1;
+  const int biased = a + (mask >> 1) + ((a >> bits) & 1);
+  assert(bits > 0);
+  if (biased > 0xff) return 0xff;
+  return biased & ~mask;
+}
+
+// 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;
+    }
+  }
+}
+
+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 = VP8LNearLosslessBits(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;
+}