Source code
Revision control
Copy as Markdown
Other Tools
// 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.
// This C++ example decodes a JPEG XL image in one shot (all input bytes
// available at once). The example outputs the pixels and color information to a
// floating point image and an ICC profile on disk.
#include <jxl/decode.h>
#include <jxl/decode_cxx.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <vector>
bool DecodeJpegXlExif(const uint8_t* jxl, size_t size,
std::vector<uint8_t>* exif) {
auto dec = JxlDecoderMake(nullptr);
// We're only interested in the Exif boxes in this example, so don't
// subscribe to events related to pixel data.
if (JXL_DEC_SUCCESS != JxlDecoderSubscribeEvents(
dec.get(), JXL_DEC_BOX | JXL_DEC_BOX_COMPLETE)) {
fprintf(stderr, "JxlDecoderSubscribeEvents failed\n");
return false;
}
bool support_decompression = true;
if (JXL_DEC_SUCCESS != JxlDecoderSetDecompressBoxes(dec.get(), JXL_TRUE)) {
fprintf(stderr,
"NOTE: decompressing brob boxes not supported with the currently "
"used jxl library.\n");
support_decompression = false;
}
JxlDecoderSetInput(dec.get(), jxl, size);
JxlDecoderCloseInput(dec.get());
const constexpr size_t kChunkSize = 65536;
size_t output_pos = 0;
for (;;) {
JxlDecoderStatus status = JxlDecoderProcessInput(dec.get());
if (status == JXL_DEC_ERROR) {
fprintf(stderr, "Decoder error\n");
return false;
} else if (status == JXL_DEC_NEED_MORE_INPUT) {
fprintf(stderr, "Error, already provided all input\n");
return false;
} else if (status == JXL_DEC_BOX) {
if (!exif->empty()) {
size_t remaining = JxlDecoderReleaseBoxBuffer(dec.get());
exif->resize(exif->size() - remaining);
// No need to wait for JXL_DEC_SUCCESS or decode other boxes.
return true;
}
JxlBoxType type;
status = JxlDecoderGetBoxType(dec.get(), type,
TO_JXL_BOOL(support_decompression));
if (JXL_DEC_SUCCESS != status) {
fprintf(stderr, "Error, failed to get box type\n");
return false;
}
if (!memcmp(type, "Exif", 4)) {
exif->resize(kChunkSize);
JxlDecoderSetBoxBuffer(dec.get(), exif->data(), exif->size());
}
} else if (status == JXL_DEC_BOX_NEED_MORE_OUTPUT) {
size_t remaining = JxlDecoderReleaseBoxBuffer(dec.get());
output_pos += kChunkSize - remaining;
exif->resize(exif->size() + kChunkSize);
JxlDecoderSetBoxBuffer(dec.get(), exif->data() + output_pos,
exif->size() - output_pos);
} else if (status == JXL_DEC_BOX_COMPLETE) {
if (!exif->empty()) {
size_t remaining = JxlDecoderReleaseBoxBuffer(dec.get());
exif->resize(exif->size() - remaining);
return true;
}
return true;
} else {
fprintf(stderr, "Unknown decoder status\n");
return false;
}
}
}
bool LoadFile(const char* filename, std::vector<uint8_t>* out) {
FILE* file = fopen(filename, "rb");
if (!file) {
return false;
}
if (fseek(file, 0, SEEK_END) != 0) {
fclose(file);
return false;
}
long size = ftell(file); // NOLINT
// Avoid invalid file or directory.
if (size >= LONG_MAX || size < 0) {
fclose(file);
return false;
}
if (fseek(file, 0, SEEK_SET) != 0) {
fclose(file);
return false;
}
out->resize(size);
size_t readsize = fread(out->data(), 1, size, file);
if (fclose(file) != 0) {
return false;
}
return readsize == static_cast<size_t>(size);
}
bool WriteFile(const char* filename, const uint8_t* data, size_t size) {
FILE* file = fopen(filename, "wb");
if (!file) {
fprintf(stderr, "Could not open %s for writing", filename);
return false;
}
fwrite(data, 1, size, file);
if (fclose(file) != 0) {
return false;
}
return true;
}
int main(int argc, char* argv[]) {
if (argc != 3) {
fprintf(stderr,
"Usage: %s <jxl> <exif>\n"
"Where:\n"
" jxl = input JPEG XL image filename\n"
" exif = output exif filename\n"
"Output files will be overwritten.\n",
argv[0]);
return 1;
}
const char* jxl_filename = argv[1];
const char* exif_filename = argv[2];
std::vector<uint8_t> jxl;
if (!LoadFile(jxl_filename, &jxl)) {
fprintf(stderr, "couldn't load %s\n", jxl_filename);
return 1;
}
std::vector<uint8_t> exif;
if (!DecodeJpegXlExif(jxl.data(), jxl.size(), &exif)) {
fprintf(stderr, "Error while decoding the jxl file\n");
return 1;
}
if (exif.empty()) {
printf("No exif data present in this image\n");
} else {
// TODO(lode): the exif box data contains the 4-byte TIFF header at the
// beginning, check whether this is desired to be part of the output, or
// should be removed.
if (!WriteFile(exif_filename, exif.data(), exif.size())) {
fprintf(stderr, "Error while writing the exif file\n");
return 1;
}
printf("Successfully wrote %s\n", exif_filename);
}
return 0;
}