Simple PMP reader to parse Picasa's metadata

webkit/fileapi/media/picasa/pmp_test_helper.cc

+// Copyright 2013 The Chromium 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 "webkit/fileapi/media/picasa/pmp_test_helper.h"
+
+#include "base/file_util.h"
+#include "webkit/fileapi/media/picasa/pmp_constants.h"
+
+namespace fileapi {
+
+// Return a vector so we don't have to worry about memory management.
+std::vector<uint8> PmpTestHelper::MakeHeader(const uint16 field_type,
+                                             const uint32 row_count) {
+  std::vector<uint8> header(fileapi::kPmpHeaderSize);
+
+  // Copy in magic bytes.
+  memcpy(&header[fileapi::kPmpMagic1Offset], &fileapi::kPmpMagic1,
+         sizeof(fileapi::kPmpMagic1));
+  memcpy(&header[fileapi::kPmpMagic2Offset], &fileapi::kPmpMagic2,
+         sizeof(fileapi::kPmpMagic2));
+  memcpy(&header[fileapi::kPmpMagic3Offset], &fileapi::kPmpMagic3,
+         sizeof(fileapi::kPmpMagic3));
+  memcpy(&header[fileapi::kPmpMagic4Offset], &fileapi::kPmpMagic4,
+         sizeof(fileapi::kPmpMagic4));
+
+  // Copy in field type.
+  memcpy(&header[fileapi::kPmpFieldType1Offset],  &field_type, 2);
+  memcpy(&header[fileapi::kPmpFieldType2Offset], &field_type, 2);
+
+  // Copy in row count.
+  memcpy(&header[fileapi::kPmpRowCountOffset], &row_count, 4);
+
+  return header;
+}
+
+template<class T>
+std::vector<uint8> PmpTestHelper::MakeHeaderAndBody(
+    const uint16 field_type, const uint32 row_count,
+    const std::vector<T>& elems) {
+  return PmpTestHelper::CombinedVectors(
+      PmpTestHelper::MakeHeader(field_type, row_count),
+      PmpTestHelper::Flatten(elems));
+}
+
+// Explicit Instantiation for all the valid types.
+template std::vector<uint8> PmpTestHelper::MakeHeaderAndBody<std::string>(
+    const uint16, const uint32, const std::vector<std::string>&);
+template std::vector<uint8> PmpTestHelper::MakeHeaderAndBody<uint32>(
+    const uint16, const uint32, const std::vector<uint32>&);
+template std::vector<uint8> PmpTestHelper::MakeHeaderAndBody<double>(
+    const uint16, const uint32, const std::vector<double>&);
+template std::vector<uint8> PmpTestHelper::MakeHeaderAndBody<uint8>(
+    const uint16, const uint32, const std::vector<uint8>&);
+template std::vector<uint8> PmpTestHelper::MakeHeaderAndBody<uint64>(
+    const uint16, const uint32, const std::vector<uint64>&);
+
+bool PmpTestHelper::WriteToFile(const base::FilePath& path,
+                                std::vector<uint8> data) {
+  // Cast for usage in WriteFile function
+  const char* data_char = reinterpret_cast<const char*>(&data[0]);
+  size_t bytes_written = file_util::WriteFile(path, data_char, data.size());
+  return (bytes_written == data.size());
+
+}
+
+template<class T>

[vandebo (ex-Chrome), 2013/03/29 21:35:07]

I suspect all the fancy mechanisms below are longer than just writing two
versions of MakeHeaderAndBody.

[tommycli, 2013/04/01 22:19:18]

MakeHeaderAndBody is called by a number of templated functions. I'd have to make
two versions of all those functions too.

+std::vector<uint8> PmpTestHelper::Flatten(const std::vector<T>& elems) {
+  const uint8* elems0 = reinterpret_cast<const uint8*>(&elems[0]);
+  std::vector<uint8> data_body(elems0, elems0 + sizeof(T)*elems.size());
+
+  return data_body;
+}
+
+// Custom specialization for std::string.
+template<>
+std::vector<uint8> PmpTestHelper::Flatten(
+    const std::vector<std::string>& strings) {
+  std::vector<uint8> totalchars;
+
+  for(std::vector<std::string>::const_iterator it = strings.begin();
+      it != strings.end(); it++) {
+    std::copy(it->begin(), it->end(), std::back_inserter(totalchars));
+    totalchars.push_back('\0'); // Add the null termination too.
+  }
+
+  return totalchars;
+}
+
+std::vector<uint8> PmpTestHelper::CombinedVectors(const std::vector<uint8>& a,
+                                                  const std::vector<uint8>& b) {
+  std::vector<uint8> total;
+
+  std::copy(a.begin(), a.end(), std::back_inserter(total));
+  std::copy(b.begin(), b.end(), std::back_inserter(total));
+
+  return total;
+}
+
+}  // namespace fileapi