formats/png/constants.h

// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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#ifndef THIRD_PARTY_CREDENTIO_FORMATS_PNG_CONSTANTS_H_
#define THIRD_PARTY_CREDENTIO_FORMATS_PNG_CONSTANTS_H_

#include <cstdint>

#include "absl/strings/string_view.h"

namespace credentio {

// PNG format, see https://www.w3.org/TR/2003/REC-PNG-20031110/ Section 5.2
constexpr absl::string_view kPngHeader = "\x89PNG\x0d\x0a\x1a\x0a";

constexpr absl::string_view kPngChunkTypeHeader = "PNGh";
constexpr absl::string_view kPngChunkTypeEnd = "IEND";
constexpr absl::string_view kPngChunkTypeC2pa = "caBX";
constexpr absl::string_view kPngChunkTypeIdat = "IDAT";
constexpr absl::string_view kPngChunkTypeExif = "eXIf";
constexpr uint32_t kPngChunkTypeExifNum = 'eXIf';

const int64_t kPngChunkLengthSize = sizeof(uint32_t);
const int64_t kPngCrcSize = sizeof(uint32_t);

const int64_t kPngMinimumAssetSize =
    kPngHeader.size() + kPngChunkTypeEnd.size() + kPngCrcSize;

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_FORMATS_PNG_CONSTANTS_H_