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enc_splines.cc (3226B)

      1 // Copyright (c) the JPEG XL Project Authors. All rights reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style
      4 // license that can be found in the LICENSE file.
      5 
      6 #include <cstdint>
      7 #include <vector>
      8 
      9 #include "lib/jxl/base/status.h"
     10 #include "lib/jxl/enc_ans.h"
     11 #include "lib/jxl/pack_signed.h"
     12 #include "lib/jxl/splines.h"
     13 
     14 namespace jxl {
     15 
     16 struct AuxOut;
     17 enum class LayerType : uint8_t;
     18 
     19 class QuantizedSplineEncoder {
     20 public:
     21  // Only call if HasAny().
     22  static void Tokenize(const QuantizedSpline& spline,
     23                       std::vector<Token>* const tokens) {
     24    tokens->emplace_back(kNumControlPointsContext,
     25                         spline.control_points_.size());
     26    for (const auto& point : spline.control_points_) {
     27      tokens->emplace_back(kControlPointsContext, PackSigned(point.first));
     28      tokens->emplace_back(kControlPointsContext, PackSigned(point.second));
     29    }
     30    const auto encode_dct = [tokens](const int dct[32]) {
     31      for (int i = 0; i < 32; ++i) {
     32        tokens->emplace_back(kDCTContext, PackSigned(dct[i]));
     33      }
     34    };
     35    for (const auto& dct : spline.color_dct_) {
     36      encode_dct(dct);
     37    }
     38    encode_dct(spline.sigma_dct_);
     39  }
     40 };
     41 
     42 namespace {
     43 
     44 void EncodeAllStartingPoints(const std::vector<Spline::Point>& points,
     45                             std::vector<Token>* tokens) {
     46  int64_t last_x = 0;
     47  int64_t last_y = 0;
     48  for (size_t i = 0; i < points.size(); i++) {
     49    const int64_t x = lroundf(points[i].x);
     50    const int64_t y = lroundf(points[i].y);
     51    if (i == 0) {
     52      tokens->emplace_back(kStartingPositionContext, x);
     53      tokens->emplace_back(kStartingPositionContext, y);
     54    } else {
     55      tokens->emplace_back(kStartingPositionContext, PackSigned(x - last_x));
     56      tokens->emplace_back(kStartingPositionContext, PackSigned(y - last_y));
     57    }
     58    last_x = x;
     59    last_y = y;
     60  }
     61 }
     62 
     63 }  // namespace
     64 
     65 Status EncodeSplines(const Splines& splines, BitWriter* writer,
     66                     const LayerType layer,
     67                     const HistogramParams& histogram_params, AuxOut* aux_out) {
     68  JXL_ENSURE(splines.HasAny());
     69 
     70  const std::vector<QuantizedSpline>& quantized_splines =
     71      splines.QuantizedSplines();
     72  std::vector<std::vector<Token>> tokens(1);
     73  tokens[0].emplace_back(kNumSplinesContext, quantized_splines.size() - 1);
     74  EncodeAllStartingPoints(splines.StartingPoints(), tokens.data());
     75 
     76  tokens[0].emplace_back(kQuantizationAdjustmentContext,
     77                         PackSigned(splines.GetQuantizationAdjustment()));
     78 
     79  for (const QuantizedSpline& spline : quantized_splines) {
     80    QuantizedSplineEncoder::Tokenize(spline, tokens.data());
     81  }
     82 
     83  EntropyEncodingData codes;
     84  std::vector<uint8_t> context_map;
     85  JXL_ASSIGN_OR_RETURN(
     86      size_t cost,
     87      BuildAndEncodeHistograms(writer->memory_manager(), histogram_params,
     88                               kNumSplineContexts, tokens, &codes, &context_map,
     89                               writer, layer, aux_out));
     90  (void)cost;
     91  JXL_RETURN_IF_ERROR(
     92      WriteTokens(tokens[0], codes, context_map, 0, writer, layer, aux_out));
     93  return true;
     94 }
     95 
     96 Splines FindSplines(const Image3F& opsin) {
     97  // TODO(user): implement spline detection.
     98  return {};
     99 }
    100 
    101 }  // namespace jxl