core/fpdfapi/parser/fpdf_parser_decode.h

// Copyright 2016 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#ifndef CORE_FPDFAPI_PARSER_FPDF_PARSER_DECODE_H_
#define CORE_FPDFAPI_PARSER_FPDF_PARSER_DECODE_H_

#include <stdint.h>

#include <array>
#include <memory>
#include <optional>
#include <utility>
#include <vector>

#include "core/fxcodec/data_and_bytes_consumed.h"
#include "core/fxcrt/data_vector.h"
#include "core/fxcrt/fx_string.h"
#include "core/fxcrt/retain_ptr.h"
#include "core/fxcrt/span.h"

class CPDF_Array;
class CPDF_Dictionary;
class CPDF_Object;

namespace fxcodec {

class ScanlineDecoder;

// Parameters come from ISO 32000-1:2008, table 8.
struct DecodeParams {
  int predictor = 0;
  int colors = 1;
  int bits_per_component = 8;
  int columns = 1;
  bool early_change = true;
};

}  // namespace fxcodec

// Indexed by 8-bit char code, contains unicode code points.
extern const std::array<uint16_t, 256> kPDFDocEncoding;

bool ValidateDecoderPipeline(const CPDF_Array* pDecoders);

ByteString PDF_EncodeString(ByteStringView src);
ByteString PDF_HexEncodeString(ByteStringView src);
WideString PDF_DecodeText(pdfium::span<const uint8_t> span);
ByteString PDF_EncodeText(WideStringView str);

std::unique_ptr<fxcodec::ScanlineDecoder> CreateFaxDecoder(
    pdfium::span<const uint8_t> src_span,
    int width,
    int height,
    const CPDF_Dictionary* pParams);

std::unique_ptr<fxcodec::ScanlineDecoder> CreateFlateDecoder(
    pdfium::span<const uint8_t> src_span,
    int width,
    int height,
    int nComps,
    int bpc,
    const CPDF_Dictionary* pParams);

fxcodec::DataAndBytesConsumed RunLengthDecode(
    pdfium::span<const uint8_t> src_span);

fxcodec::DataAndBytesConsumed A85Decode(pdfium::span<const uint8_t> src_span);

fxcodec::DataAndBytesConsumed HexDecode(pdfium::span<const uint8_t> src_span);

fxcodec::DataAndBytesConsumed FlateOrLZWDecode(
    bool use_lzw,
    pdfium::span<const uint8_t> src_span,
    const CPDF_Dictionary* pParams,
    uint32_t estimated_size);

// Returns std::nullopt if the filter in |dict| is the wrong type or an
// invalid decoder pipeline.
// Returns an empty vector if there is no filter, or if the filter is an empty
// array.
// Otherwise, returns a vector of decoders.
using DecoderArray =
    std::vector<std::pair<ByteString, RetainPtr<const CPDF_Object>>>;
std::optional<DecoderArray> GetDecoderArray(
    RetainPtr<const CPDF_Dictionary> dict);

// May return a struct for the DecodeParams. Returns default values if params
// is a nullptr and returns std::nullopt if the DecodeParams are invalid.
std::optional<fxcodec::DecodeParams> GetAndCheckDecodeParams(
    const CPDF_Dictionary* params);

struct PDFDataDecodeResult {
  PDFDataDecodeResult();
  PDFDataDecodeResult(DataVector<uint8_t> data,
                      ByteString image_encoding,
                      RetainPtr<const CPDF_Dictionary> image_params);
  PDFDataDecodeResult(PDFDataDecodeResult&& that) noexcept;
  PDFDataDecodeResult& operator=(PDFDataDecodeResult&& that) noexcept;
  ~PDFDataDecodeResult();

  DataVector<uint8_t> data;
  ByteString image_encoding;
  RetainPtr<const CPDF_Dictionary> image_params;
};

std::optional<PDFDataDecodeResult> PDF_DataDecode(
    pdfium::span<const uint8_t> src_span,
    uint32_t estimated_size,
    bool bImageAcc,
    const DecoderArray& decoder_array);

#endif  // CORE_FPDFAPI_PARSER_FPDF_PARSER_DECODE_H_