Update libwebp to 0.6.1

* lossless performance and compression improvements + a new 'cruncher' mode (-m 6 -q 100)
* ARM performance improvements with clang (15-20% w/ndk r15c)
* webp-js: emscripten/webassembly based javascript decoder
* miscellaneous bug & build fixes

1 files changed, 148 insertions, 0 deletions

diff --git a/thirdparty/libwebp/src/utils/rescaler_utils.c b/thirdparty/libwebp/src/utils/rescaler_utils.c
new file mode 100644
index 0000000000..90e2ea76a1
--- /dev/null
+++ b/thirdparty/libwebp/src/utils/rescaler_utils.c
@@ -0,0 +1,148 @@
+// Copyright 2012 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.
+// -----------------------------------------------------------------------------
+//
+// Rescaling functions
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include "src/dsp/dsp.h"
+#include "src/utils/rescaler_utils.h"
+
+//------------------------------------------------------------------------------
+
+void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
+                      uint8_t* const dst,
+                      int dst_width, int dst_height, int dst_stride,
+                      int num_channels, rescaler_t* const work) {
+  const int x_add = src_width, x_sub = dst_width;
+  const int y_add = src_height, y_sub = dst_height;
+  wrk->x_expand = (src_width < dst_width);
+  wrk->y_expand = (src_height < dst_height);
+  wrk->src_width = src_width;
+  wrk->src_height = src_height;
+  wrk->dst_width = dst_width;
+  wrk->dst_height = dst_height;
+  wrk->src_y = 0;
+  wrk->dst_y = 0;
+  wrk->dst = dst;
+  wrk->dst_stride = dst_stride;
+  wrk->num_channels = num_channels;
+
+  // for 'x_expand', we use bilinear interpolation
+  wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add;
+  wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub;
+  if (!wrk->x_expand) {  // fx_scale is not used otherwise
+    wrk->fx_scale = WEBP_RESCALER_FRAC(1, wrk->x_sub);
+  }
+  // vertical scaling parameters
+  wrk->y_add = wrk->y_expand ? y_add - 1 : y_add;
+  wrk->y_sub = wrk->y_expand ? y_sub - 1 : y_sub;
+  wrk->y_accum = wrk->y_expand ? wrk->y_sub : wrk->y_add;
+  if (!wrk->y_expand) {
+    // This is WEBP_RESCALER_FRAC(dst_height, x_add * y_add) without the cast.
+    // Its value is <= WEBP_RESCALER_ONE, because dst_height <= wrk->y_add, and
+    // wrk->x_add >= 1;
+    const uint64_t ratio =
+        (uint64_t)dst_height * WEBP_RESCALER_ONE / (wrk->x_add * wrk->y_add);
+    if (ratio != (uint32_t)ratio) {
+      // When ratio == WEBP_RESCALER_ONE, we can't represent the ratio with the
+      // current fixed-point precision. This happens when src_height ==
+      // wrk->y_add (which == src_height), and wrk->x_add == 1.
+      // => We special-case fxy_scale = 0, in WebPRescalerExportRow().
+      wrk->fxy_scale = 0;
+    } else {
+      wrk->fxy_scale = (uint32_t)ratio;
+    }
+    wrk->fy_scale = WEBP_RESCALER_FRAC(1, wrk->y_sub);
+  } else {
+    wrk->fy_scale = WEBP_RESCALER_FRAC(1, wrk->x_add);
+    // wrk->fxy_scale is unused here.
+  }
+  wrk->irow = work;
+  wrk->frow = work + num_channels * dst_width;
+  memset(work, 0, 2 * dst_width * num_channels * sizeof(*work));
+
+  WebPRescalerDspInit();
+}
+
+int WebPRescalerGetScaledDimensions(int src_width, int src_height,
+                                    int* const scaled_width,
+                                    int* const scaled_height) {
+  assert(scaled_width != NULL);
+  assert(scaled_height != NULL);
+  {
+    int width = *scaled_width;
+    int height = *scaled_height;
+
+    // if width is unspecified, scale original proportionally to height ratio.
+    if (width == 0) {
+      width =
+          (int)(((uint64_t)src_width * height + src_height / 2) / src_height);
+    }
+    // if height is unspecified, scale original proportionally to width ratio.
+    if (height == 0) {
+      height =
+          (int)(((uint64_t)src_height * width + src_width / 2) / src_width);
+    }
+    // Check if the overall dimensions still make sense.
+    if (width <= 0 || height <= 0) {
+      return 0;
+    }
+
+    *scaled_width = width;
+    *scaled_height = height;
+    return 1;
+  }
+}
+
+//------------------------------------------------------------------------------
+// all-in-one calls
+
+int WebPRescaleNeededLines(const WebPRescaler* const wrk, int max_num_lines) {
+  const int num_lines = (wrk->y_accum + wrk->y_sub - 1) / wrk->y_sub;
+  return (num_lines > max_num_lines) ? max_num_lines : num_lines;
+}
+
+int WebPRescalerImport(WebPRescaler* const wrk, int num_lines,
+                       const uint8_t* src, int src_stride) {
+  int total_imported = 0;
+  while (total_imported < num_lines && !WebPRescalerHasPendingOutput(wrk)) {
+    if (wrk->y_expand) {
+      rescaler_t* const tmp = wrk->irow;
+      wrk->irow = wrk->frow;
+      wrk->frow = tmp;
+    }
+    WebPRescalerImportRow(wrk, src);
+    if (!wrk->y_expand) {     // Accumulate the contribution of the new row.
+      int x;
+      for (x = 0; x < wrk->num_channels * wrk->dst_width; ++x) {
+        wrk->irow[x] += wrk->frow[x];
+      }
+    }
+    ++wrk->src_y;
+    src += src_stride;
+    ++total_imported;
+    wrk->y_accum -= wrk->y_sub;
+  }
+  return total_imported;
+}
+
+int WebPRescalerExport(WebPRescaler* const rescaler) {
+  int total_exported = 0;
+  while (WebPRescalerHasPendingOutput(rescaler)) {
+    WebPRescalerExportRow(rescaler);
+    ++total_exported;
+  }
+  return total_exported;
+}
+
+//------------------------------------------------------------------------------