1 files changed, 123 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/extras/enc/pgx.cc b/third_party/jpeg-xl/lib/extras/enc/pgx.cc
new file mode 100644
index 0000000000..201c8b4189
--- /dev/null
+++ b/third_party/jpeg-xl/lib/extras/enc/pgx.cc
@@ -0,0 +1,123 @@
+// 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/enc/pgx.h"
+
+#include <jxl/codestream_header.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "lib/extras/packed_image.h"
+#include "lib/jxl/base/byte_order.h"
+
+namespace jxl {
+namespace extras {
+namespace {
+
+constexpr size_t kMaxHeaderSize = 200;
+
+Status EncodeHeader(const JxlBasicInfo& info, char* header,
+                    int* chars_written) {
+  if (info.alpha_bits > 0) {
+    return JXL_FAILURE("PGX: can't store alpha");
+  }
+  if (info.num_color_channels != 1) {
+    return JXL_FAILURE("PGX: must be grayscale");
+  }
+  // TODO(lode): verify other bit depths: for other bit depths such as 1 or 4
+  // bits, have a test case to verify it works correctly. For bits > 16, we may
+  // need to change the way external_image works.
+  if (info.bits_per_sample != 8 && info.bits_per_sample != 16) {
+    return JXL_FAILURE("PGX: bits other than 8 or 16 not yet supported");
+  }
+
+  // Use ML (Big Endian), LM may not be well supported by all decoders.
+  *chars_written = snprintf(header, kMaxHeaderSize, "PG ML + %u %u %u\n",
+                            info.bits_per_sample, info.xsize, info.ysize);
+  JXL_RETURN_IF_ERROR(static_cast<unsigned int>(*chars_written) <
+                      kMaxHeaderSize);
+  return true;
+}
+
+Status EncodeImagePGX(const PackedFrame& frame, const JxlBasicInfo& info,
+                      std::vector<uint8_t>* bytes) {
+  char header[kMaxHeaderSize];
+  int header_size = 0;
+  JXL_RETURN_IF_ERROR(EncodeHeader(info, header, &header_size));
+
+  const PackedImage& color = frame.color;
+  const JxlPixelFormat format = color.format;
+  const uint8_t* in = reinterpret_cast<const uint8_t*>(color.pixels());
+  size_t data_bits_per_sample = PackedImage::BitsPerChannel(format.data_type);
+  size_t bytes_per_sample = data_bits_per_sample / kBitsPerByte;
+  size_t num_samples = info.xsize * info.ysize;
+
+  if (info.bits_per_sample != data_bits_per_sample) {
+    return JXL_FAILURE("Bit depth does not match pixel data type");
+  }
+
+  std::vector<uint8_t> pixels(num_samples * bytes_per_sample);
+
+  if (format.data_type == JXL_TYPE_UINT8) {
+    memcpy(&pixels[0], in, num_samples * bytes_per_sample);
+  } else if (format.data_type == JXL_TYPE_UINT16) {
+    if (format.endianness != JXL_BIG_ENDIAN) {
+      const uint8_t* p_in = in;
+      uint8_t* p_out = pixels.data();
+      for (size_t i = 0; i < num_samples; ++i, p_in += 2, p_out += 2) {
+        StoreBE16(LoadLE16(p_in), p_out);
+      }
+    } else {
+      memcpy(&pixels[0], in, num_samples * bytes_per_sample);
+    }
+  } else {
+    return JXL_FAILURE("Unsupported pixel data type");
+  }
+
+  bytes->resize(static_cast<size_t>(header_size) + pixels.size());
+  memcpy(bytes->data(), header, static_cast<size_t>(header_size));
+  memcpy(bytes->data() + header_size, pixels.data(), pixels.size());
+
+  return true;
+}
+
+class PGXEncoder : public Encoder {
+ public:
+  std::vector<JxlPixelFormat> AcceptedFormats() const override {
+    std::vector<JxlPixelFormat> formats;
+    for (const JxlDataType data_type : {JXL_TYPE_UINT8, JXL_TYPE_UINT16}) {
+      for (JxlEndianness endianness : {JXL_BIG_ENDIAN, JXL_LITTLE_ENDIAN}) {
+        formats.push_back(JxlPixelFormat{/*num_channels=*/1,
+                                         /*data_type=*/data_type,
+                                         /*endianness=*/endianness,
+                                         /*align=*/0});
+      }
+    }
+    return formats;
+  }
+  Status Encode(const PackedPixelFile& ppf, EncodedImage* encoded_image,
+                ThreadPool* pool) const override {
+    JXL_RETURN_IF_ERROR(VerifyBasicInfo(ppf.info));
+    encoded_image->icc.assign(ppf.icc.begin(), ppf.icc.end());
+    encoded_image->bitstreams.clear();
+    encoded_image->bitstreams.reserve(ppf.frames.size());
+    for (const auto& frame : ppf.frames) {
+      JXL_RETURN_IF_ERROR(VerifyPackedImage(frame.color, ppf.info));
+      encoded_image->bitstreams.emplace_back();
+      JXL_RETURN_IF_ERROR(
+          EncodeImagePGX(frame, ppf.info, &encoded_image->bitstreams.back()));
+    }
+    return true;
+  }
+};
+
+}  // namespace
+
+std::unique_ptr<Encoder> GetPGXEncoder() {
+  return jxl::make_unique<PGXEncoder>();
+}
+
+}  // namespace extras
+}  // namespace jxl