core/fxcodec/image_predictors.h

// Copyright 2026 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CORE_FXCODEC_IMAGE_PREDICTORS_H_
#define CORE_FXCODEC_IMAGE_PREDICTORS_H_

#include <stddef.h>
#include <stdint.h>

#include <optional>

#include "core/fxcrt/data_vector.h"
#include "core/fxcrt/span.h"

namespace fxcodec {

enum class PredictorType : uint8_t { kNone, kTiff, kPng };

// Values come from ISO 32000-1:2008, table 10.
PredictorType GetPredictor(int predictor);

void PngPredictLine(pdfium::span<uint8_t> dest_span,
                    pdfium::span<const uint8_t> src_span,
                    pdfium::span<const uint8_t> last_span,
                    size_t row_size,
                    uint32_t bytes_per_pixel);

std::optional<DataVector<uint8_t>> PngPredictor(
    int colors,
    int bits_per_component,
    int columns,
    pdfium::span<const uint8_t> src_span);

void TiffPredictLine(pdfium::span<uint8_t> dest_span,
                     int bits_per_component,
                     int colors,
                     int columns);

bool TiffPredictor(int colors,
                   int bits_per_component,
                   int columns,
                   pdfium::span<uint8_t> data_span);

}  // namespace fxcodec

#endif  // CORE_FXCODEC_IMAGE_PREDICTORS_H_