diff options
Diffstat (limited to 'media/libjxl/src/lib/extras/dec/pgx.cc')
| -rw-r--r-- | media/libjxl/src/lib/extras/dec/pgx.cc | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/media/libjxl/src/lib/extras/dec/pgx.cc b/media/libjxl/src/lib/extras/dec/pgx.cc new file mode 100644 index 0000000000..1417348c61 --- /dev/null +++ b/media/libjxl/src/lib/extras/dec/pgx.cc @@ -0,0 +1,202 @@ +// Copyright (c) the JPEG XL Project Authors. All rights reserved. +// +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#include "lib/extras/dec/pgx.h" + +#include <string.h> + +#include "lib/jxl/base/bits.h" +#include "lib/jxl/base/compiler_specific.h" + +namespace jxl { +namespace extras { +namespace { + +struct HeaderPGX { + // NOTE: PGX is always grayscale + size_t xsize; + size_t ysize; + size_t bits_per_sample; + bool big_endian; + bool is_signed; +}; + +class Parser { + public: + explicit Parser(const Span<const uint8_t> bytes) + : pos_(bytes.data()), end_(pos_ + bytes.size()) {} + + // Sets "pos" to the first non-header byte/pixel on success. + Status ParseHeader(HeaderPGX* header, const uint8_t** pos) { + // codec.cc ensures we have at least two bytes => no range check here. + if (pos_[0] != 'P' || pos_[1] != 'G') return false; + pos_ += 2; + return ParseHeaderPGX(header, pos); + } + + // Exposed for testing + Status ParseUnsigned(size_t* number) { + if (pos_ == end_) return JXL_FAILURE("PGX: reached end before number"); + if (!IsDigit(*pos_)) return JXL_FAILURE("PGX: expected unsigned number"); + + *number = 0; + while (pos_ < end_ && *pos_ >= '0' && *pos_ <= '9') { + *number *= 10; + *number += *pos_ - '0'; + ++pos_; + } + + return true; + } + + private: + static bool IsDigit(const uint8_t c) { return '0' <= c && c <= '9'; } + static bool IsLineBreak(const uint8_t c) { return c == '\r' || c == '\n'; } + static bool IsWhitespace(const uint8_t c) { + return IsLineBreak(c) || c == '\t' || c == ' '; + } + + Status SkipSpace() { + if (pos_ == end_) return JXL_FAILURE("PGX: reached end before space"); + const uint8_t c = *pos_; + if (c != ' ') return JXL_FAILURE("PGX: expected space"); + ++pos_; + return true; + } + + Status SkipLineBreak() { + if (pos_ == end_) return JXL_FAILURE("PGX: reached end before line break"); + // Line break can be either "\n" (0a) or "\r\n" (0d 0a). + if (*pos_ == '\n') { + pos_++; + return true; + } else if (*pos_ == '\r' && pos_ + 1 != end_ && *(pos_ + 1) == '\n') { + pos_ += 2; + return true; + } + return JXL_FAILURE("PGX: expected line break"); + } + + Status SkipSingleWhitespace() { + if (pos_ == end_) return JXL_FAILURE("PGX: reached end before whitespace"); + if (!IsWhitespace(*pos_)) return JXL_FAILURE("PGX: expected whitespace"); + ++pos_; + return true; + } + + Status ParseHeaderPGX(HeaderPGX* header, const uint8_t** pos) { + JXL_RETURN_IF_ERROR(SkipSpace()); + if (pos_ + 2 > end_) return JXL_FAILURE("PGX: header too small"); + if (*pos_ == 'M' && *(pos_ + 1) == 'L') { + header->big_endian = true; + } else if (*pos_ == 'L' && *(pos_ + 1) == 'M') { + header->big_endian = false; + } else { + return JXL_FAILURE("PGX: invalid endianness"); + } + pos_ += 2; + JXL_RETURN_IF_ERROR(SkipSpace()); + if (pos_ == end_) return JXL_FAILURE("PGX: header too small"); + if (*pos_ == '+') { + header->is_signed = false; + } else if (*pos_ == '-') { + header->is_signed = true; + } else { + return JXL_FAILURE("PGX: invalid signedness"); + } + pos_++; + // Skip optional space + if (pos_ < end_ && *pos_ == ' ') pos_++; + JXL_RETURN_IF_ERROR(ParseUnsigned(&header->bits_per_sample)); + JXL_RETURN_IF_ERROR(SkipSingleWhitespace()); + JXL_RETURN_IF_ERROR(ParseUnsigned(&header->xsize)); + JXL_RETURN_IF_ERROR(SkipSingleWhitespace()); + JXL_RETURN_IF_ERROR(ParseUnsigned(&header->ysize)); + // 0xa, or 0xd 0xa. + JXL_RETURN_IF_ERROR(SkipLineBreak()); + + // TODO(jon): could do up to 24-bit by converting the values to + // JXL_TYPE_FLOAT. + if (header->bits_per_sample > 16) { + return JXL_FAILURE("PGX: >16 bits not yet supported"); + } + // TODO(lode): support signed integers. This may require changing the way + // external_image works. + if (header->is_signed) { + return JXL_FAILURE("PGX: signed not yet supported"); + } + + size_t numpixels = header->xsize * header->ysize; + size_t bytes_per_pixel = header->bits_per_sample <= 8 ? 1 : 2; + if (pos_ + numpixels * bytes_per_pixel > end_) { + return JXL_FAILURE("PGX: data too small"); + } + + *pos = pos_; + return true; + } + + const uint8_t* pos_; + const uint8_t* const end_; +}; + +} // namespace + +Status DecodeImagePGX(const Span<const uint8_t> bytes, + const ColorHints& color_hints, + const SizeConstraints& constraints, + PackedPixelFile* ppf) { + Parser parser(bytes); + HeaderPGX header = {}; + const uint8_t* pos; + if (!parser.ParseHeader(&header, &pos)) return false; + JXL_RETURN_IF_ERROR( + VerifyDimensions(&constraints, header.xsize, header.ysize)); + if (header.bits_per_sample == 0 || header.bits_per_sample > 32) { + return JXL_FAILURE("PGX: bits_per_sample invalid"); + } + + JXL_RETURN_IF_ERROR(ApplyColorHints(color_hints, /*color_already_set=*/false, + /*is_gray=*/true, ppf)); + ppf->info.xsize = header.xsize; + ppf->info.ysize = header.ysize; + // Original data is uint, so exponent_bits_per_sample = 0. + ppf->info.bits_per_sample = header.bits_per_sample; + ppf->info.exponent_bits_per_sample = 0; + ppf->info.uses_original_profile = true; + + // No alpha in PGX + ppf->info.alpha_bits = 0; + ppf->info.alpha_exponent_bits = 0; + ppf->info.num_color_channels = 1; // Always grayscale + ppf->info.orientation = JXL_ORIENT_IDENTITY; + + JxlDataType data_type; + if (header.bits_per_sample > 8) { + data_type = JXL_TYPE_UINT16; + } else { + data_type = JXL_TYPE_UINT8; + } + + const JxlPixelFormat format{ + /*num_channels=*/1, + /*data_type=*/data_type, + /*endianness=*/header.big_endian ? JXL_BIG_ENDIAN : JXL_LITTLE_ENDIAN, + /*align=*/0, + }; + ppf->frames.clear(); + // Allocates the frame buffer. + ppf->frames.emplace_back(header.xsize, header.ysize, format); + const auto& frame = ppf->frames.back(); + size_t pgx_remaining_size = bytes.data() + bytes.size() - pos; + if (pgx_remaining_size < frame.color.pixels_size) { + return JXL_FAILURE("PGX file too small"); + } + memcpy(frame.color.pixels(), pos, frame.color.pixels_size); + return true; +} + +} // namespace extras +} // namespace jxl |