guest/hals/camera/Exif.cpp - device/google/cuttlefish - Git at Google

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * 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
  *
  *      http://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.
  */

 #define LOG_NDEBUG 0
 #define LOG_TAG "EmulatedCamera_Exif"
 #include <log/log.h>

 #include <inttypes.h>
 #include <math.h>
 #include <stdint.h>

 #include <CameraParameters.h>

 using ::android::hardware::camera::common::V1_0::helper::CameraParameters;
 using ::android::hardware::camera::common::V1_0::helper::Size;

 #include "Exif.h"

 #include <libexif/exif-data.h>
 #include <libexif/exif-entry.h>
 #include <libexif/exif-ifd.h>
 #include <libexif/exif-tag.h>

 #include <string>
 #include <vector>

 // For GPS timestamping we want to ensure we use a 64-bit time_t, 32-bit
 // platforms have time64_t but 64-bit platforms do not.
 #if defined(__LP64__)
 #include <time.h>
 using Timestamp = time_t;
 #define TIMESTAMP_TO_TM(timestamp, tm) gmtime_r(timestamp, tm)
 #else
 #include <time64.h>
 using Timestamp = time64_t;
 #define TIMESTAMP_TO_TM(timestamp, tm) gmtime64_r(timestamp, tm)
 #endif

 namespace android {

 // A prefix that is used for tags with the "undefined" format to indicate that
 // the contents are ASCII encoded. See the user comment section of the EXIF spec
 // for more details http://www.exif.org/Exif2-2.PDF
 static const unsigned char kAsciiPrefix[] = {
     0x41, 0x53, 0x43, 0x49, 0x49, 0x00, 0x00, 0x00 // "ASCII\0\0\0"
 };

 // Remove an existing EXIF entry from |exifData| if it exists. This is useful
 // when replacing existing data, it's easier to just remove the data and
 // re-allocate it than to adjust the amount of allocated data.
 static void removeExistingEntry(ExifData* exifData, ExifIfd ifd, int tag) {
     ExifEntry* entry = exif_content_get_entry(exifData->ifd[ifd],
                                               static_cast<ExifTag>(tag));
     if (entry) {
         exif_content_remove_entry(exifData->ifd[ifd], entry);
     }
 }

 static ExifEntry* allocateEntry(int tag,
                                 ExifFormat format,
                                 unsigned int numComponents) {
     ExifMem* mem = exif_mem_new_default();
     ExifEntry* entry = exif_entry_new_mem(mem);

     unsigned int size = numComponents * exif_format_get_size(format);
     entry->data = reinterpret_cast<unsigned char*>(exif_mem_alloc(mem, size));
     entry->size = size;
     entry->tag = static_cast<ExifTag>(tag);
     entry->components = numComponents;
     entry->format = format;

     exif_mem_unref(mem);
     return entry;
 }

 // Create an entry and place it in |exifData|, the entry is initialized with an
 // array of floats from |values|
 template<size_t N>
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         const float (&values)[N],
                         float denominator = 1000.0) {
     removeExistingEntry(exifData, ifd, tag);
     ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
     ExifEntry* entry = allocateEntry(tag, EXIF_FORMAT_RATIONAL, N);
     exif_content_add_entry(exifData->ifd[ifd], entry);
     unsigned int rationalSize = exif_format_get_size(EXIF_FORMAT_RATIONAL);
     for (size_t i = 0; i < N; ++i) {
         ExifRational rational = {
             static_cast<uint32_t>(values[i] * denominator),
             static_cast<uint32_t>(denominator)
         };

         exif_set_rational(&entry->data[i * rationalSize], byteOrder, rational);
     }

     // Unref entry after changing owner to the ExifData struct
     exif_entry_unref(entry);
     return true;
 }

 // Create an entry with a single float |value| in it and place it in |exifData|
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         const float value,
                         float denominator = 1000.0) {
     float values[1] = { value };
     // Recycling functions is good for the environment
     return createEntry(exifData, ifd, tag, values, denominator);
 }

 // Create an entry and place it in |exifData|, the entry contains the raw data
 // pointed to by |data| of length |size|.
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         const unsigned char* data,
                         size_t size,
                         ExifFormat format = EXIF_FORMAT_UNDEFINED) {
     removeExistingEntry(exifData, ifd, tag);
     ExifEntry* entry = allocateEntry(tag, format, size);
     memcpy(entry->data, data, size);
     exif_content_add_entry(exifData->ifd[ifd], entry);
     // Unref entry after changing owner to the ExifData struct
     exif_entry_unref(entry);
     return true;
 }

 // Create an entry and place it in |exifData|, the entry is initialized with
 // the string provided in |value|
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         const char* value) {
     unsigned int length = strlen(value) + 1;
     const unsigned char* data = reinterpret_cast<const unsigned char*>(value);
     return createEntry(exifData, ifd, tag, data, length, EXIF_FORMAT_ASCII);
 }

 // Create an entry and place it in |exifData|, the entry is initialized with a
 // single byte in |value|
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         uint8_t value) {
     return createEntry(exifData, ifd, tag, &value, 1, EXIF_FORMAT_BYTE);
 }

 // Create an entry and place it in |exifData|, the entry is default initialized
 // by the exif library based on |tag|
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag) {
     removeExistingEntry(exifData, ifd, tag);
     ExifEntry* entry = exif_entry_new();
     exif_content_add_entry(exifData->ifd[ifd], entry);
     exif_entry_initialize(entry, static_cast<ExifTag>(tag));
     // Unref entry after changing owner to the ExifData struct
     exif_entry_unref(entry);
     return true;
 }

 // Create an entry with a single EXIF LONG (32-bit value) and place it in
 // |exifData|.
 static bool createEntry(ExifData* exifData,
                         ExifIfd ifd,
                         int tag,
                         int value) {
     removeExistingEntry(exifData, ifd, tag);
     ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
     ExifEntry* entry = allocateEntry(tag, EXIF_FORMAT_LONG, 1);
     exif_content_add_entry(exifData->ifd[ifd], entry);
     exif_set_long(entry->data, byteOrder, value);

     // Unref entry after changing owner to the ExifData struct
     exif_entry_unref(entry);
     return true;
 }

 static bool getCameraParam(const CameraParameters& parameters,
                            const char* parameterKey,
                            const char** outValue) {
     const char* value = parameters.get(parameterKey);
     if (value) {
         *outValue = value;
         return true;
     }
     return false;
 }

 static bool getCameraParam(const CameraParameters& parameters,
                            const char* parameterKey,
                            float* outValue) {
     const char* value = parameters.get(parameterKey);
     if (value) {
         *outValue = parameters.getFloat(parameterKey);
         return true;
     }
     return false;
 }

 static bool getCameraParam(const CameraParameters& parameters,
                            const char* parameterKey,
                            int64_t* outValue) {
     const char* value = parameters.get(parameterKey);
     if (value) {
         char dummy = 0;
         // Attempt to scan an extra character and then make sure it was not
         // scanned by checking that the return value indicates only one item.
         // This way we fail on any trailing characters
         if (sscanf(value, "%" SCNd64 "%c", outValue, &dummy) == 1) {
             return true;
         }
     }
     return false;
 }

 // Convert a GPS coordinate represented as a decimal degree value to sexagesimal
 // GPS coordinates comprised of <degrees> <minutes>' <seconds>"
 static void convertGpsCoordinate(float degrees, float (*result)[3]) {
     float absDegrees = fabs(degrees);
     // First value is degrees without any decimal digits
     (*result)[0] = floor(absDegrees);

     // Subtract degrees so we only have the fraction left, then multiply by
     // 60 to get the minutes
     float minutes = (absDegrees - (*result)[0]) * 60.0f;
     (*result)[1] = floor(minutes);

     // Same thing for seconds but here we store seconds with the fraction
     float seconds = (minutes - (*result)[1]) * 60.0f;
     (*result)[2] = seconds;
 }

 // Convert a UNIX epoch timestamp to a timestamp comprised of three floats for
 // hour, minute and second, and a date part that is represented as a string.
 static bool convertTimestampToTimeAndDate(int64_t timestamp,
                                           float (*timeValues)[3],
                                           std::string* date) {
     Timestamp time = timestamp;
     struct tm utcTime;
     if (TIMESTAMP_TO_TM(&time, &utcTime) == nullptr) {
         ALOGE("Could not decompose timestamp into components");
         return false;
     }
     (*timeValues)[0] = utcTime.tm_hour;
     (*timeValues)[1] = utcTime.tm_min;
     (*timeValues)[2] = utcTime.tm_sec;

     char buffer[64] = {};
     if (strftime(buffer, sizeof(buffer), "%Y:%m:%d", &utcTime) == 0) {
         ALOGE("Could not construct date string from timestamp");
         return false;
     }
     *date = buffer;
     return true;
 }

 ExifData* createExifData(const CameraParameters& params) {
     ExifData* exifData = exif_data_new();

     exif_data_set_option(exifData, EXIF_DATA_OPTION_FOLLOW_SPECIFICATION);
     exif_data_set_data_type(exifData, EXIF_DATA_TYPE_COMPRESSED);
     exif_data_set_byte_order(exifData, EXIF_BYTE_ORDER_INTEL);

     // Create mandatory exif fields and set their default values
     exif_data_fix(exifData);

     float triplet[3];
     float floatValue = 0.0f;
     const char* stringValue;
     int64_t degrees;

     // Datetime, creating and initializing a datetime tag will automatically
     // set the current date and time in the tag so just do that.
     createEntry(exifData, EXIF_IFD_0, EXIF_TAG_DATE_TIME);

     // Make and model
     createEntry(exifData, EXIF_IFD_0, EXIF_TAG_MAKE, "Emulator-Cuttlefish");
     createEntry(exifData, EXIF_IFD_0, EXIF_TAG_MODEL, "Emulator-Cuttlefish");

     // Picture size
     int width = -1, height = -1;
     params.getPictureSize(&width, &height);
     if (width >= 0 && height >= 0) {
         createEntry(exifData, EXIF_IFD_EXIF,
                     EXIF_TAG_PIXEL_X_DIMENSION, width);
         createEntry(exifData, EXIF_IFD_EXIF,
                     EXIF_TAG_PIXEL_Y_DIMENSION, height);
     }
     // Orientation
     if (getCameraParam(params,
                        CameraParameters::KEY_ROTATION,
                        &degrees)) {
         // Exif orientation values, please refer to
         // http://www.exif.org/Exif2-2.PDF, Section 4.6.4-A-Orientation
         // Or these websites:
         // http://sylvana.net/jpegcrop/exif_orientation.html
         // http://www.impulseadventure.com/photo/exif-orientation.html
         enum {
             EXIF_ROTATE_CAMERA_CW0 = 1,
             EXIF_ROTATE_CAMERA_CW90 = 6,
             EXIF_ROTATE_CAMERA_CW180 = 3,
             EXIF_ROTATE_CAMERA_CW270 = 8,
         };
         uint16_t exifOrien = 1;
         switch (degrees) {
             case 0:
                 exifOrien = EXIF_ROTATE_CAMERA_CW0;
                 break;
             case 90:
                 exifOrien = EXIF_ROTATE_CAMERA_CW90;
                 break;
             case 180:
                 exifOrien = EXIF_ROTATE_CAMERA_CW180;
                 break;
             case 270:
                 exifOrien = EXIF_ROTATE_CAMERA_CW270;
                 break;
         }
         createEntry(exifData, EXIF_IFD_0, EXIF_TAG_ORIENTATION, exifOrien);
     }
     // Focal length
     if (getCameraParam(params,
                        CameraParameters::KEY_FOCAL_LENGTH,
                        &floatValue)) {
         createEntry(exifData, EXIF_IFD_EXIF, EXIF_TAG_FOCAL_LENGTH, floatValue);
     }
     // GPS latitude and reference, reference indicates sign, store unsigned
     if (getCameraParam(params,
                        CameraParameters::KEY_GPS_LATITUDE,
                        &floatValue)) {
         convertGpsCoordinate(floatValue, &triplet);
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LATITUDE, triplet);

         const char* ref = floatValue < 0.0f ? "S" : "N";
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LATITUDE_REF, ref);
     }
     // GPS longitude and reference, reference indicates sign, store unsigned
     if (getCameraParam(params,
                        CameraParameters::KEY_GPS_LONGITUDE,
                        &floatValue)) {
         convertGpsCoordinate(floatValue, &triplet);
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LONGITUDE, triplet);

         const char* ref = floatValue < 0.0f ? "W" : "E";
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LONGITUDE_REF, ref);
     }
     // GPS altitude and reference, reference indicates sign, store unsigned
     if (getCameraParam(params,
                        CameraParameters::KEY_GPS_ALTITUDE,
                        &floatValue)) {
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_ALTITUDE,
                     static_cast<float>(fabs(floatValue)));

         // 1 indicated below sea level, 0 indicates above sea level
         uint8_t ref = floatValue < 0.0f ? 1 : 0;
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_ALTITUDE_REF, ref);
     }
     // GPS timestamp and datestamp
     int64_t timestamp = 0;
     if (getCameraParam(params,
                        CameraParameters::KEY_GPS_TIMESTAMP,
                        &timestamp)) {
         std::string date;
         if (convertTimestampToTimeAndDate(timestamp, &triplet, &date)) {
             createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_TIME_STAMP,
                         triplet, 1.0f);
             createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_DATE_STAMP,
                         date.c_str());
         }
     }

     // GPS processing method
     if (getCameraParam(params,
                        CameraParameters::KEY_GPS_PROCESSING_METHOD,
                        &stringValue)) {
         std::vector<unsigned char> data;
         // Because this is a tag with an undefined format it has to be prefixed
         // with the encoding type. Insert an ASCII prefix first, then the
         // actual string. Undefined tags do not have to be null terminated.
         data.insert(data.end(),
                     std::begin(kAsciiPrefix),
                     std::end(kAsciiPrefix));
         data.insert(data.end(), stringValue, stringValue + strlen(stringValue));
         createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_PROCESSING_METHOD,
                     &data[0], data.size());
     }

     return exifData;
 }

 void freeExifData(ExifData* exifData) {
     exif_data_free(exifData);
 }

 }  // namespace android
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* 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
	*
	* http://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.
	*/

	#define LOG_NDEBUG 0
	#define LOG_TAG "EmulatedCamera_Exif"
	#include <log/log.h>

	#include <inttypes.h>
	#include <math.h>
	#include <stdint.h>

	#include <CameraParameters.h>

	using ::android::hardware::camera::common::V1_0::helper::CameraParameters;
	using ::android::hardware::camera::common::V1_0::helper::Size;

	#include "Exif.h"

	#include <libexif/exif-data.h>
	#include <libexif/exif-entry.h>
	#include <libexif/exif-ifd.h>
	#include <libexif/exif-tag.h>

	#include <string>
	#include <vector>

	// For GPS timestamping we want to ensure we use a 64-bit time_t, 32-bit
	// platforms have time64_t but 64-bit platforms do not.
	#if defined(__LP64__)
	#include <time.h>
	using Timestamp = time_t;
	#define TIMESTAMP_TO_TM(timestamp, tm) gmtime_r(timestamp, tm)
	#else
	#include <time64.h>
	using Timestamp = time64_t;
	#define TIMESTAMP_TO_TM(timestamp, tm) gmtime64_r(timestamp, tm)
	#endif

	namespace android {

	// A prefix that is used for tags with the "undefined" format to indicate that
	// the contents are ASCII encoded. See the user comment section of the EXIF spec
	// for more details http://www.exif.org/Exif2-2.PDF
	static const unsigned char kAsciiPrefix[] = {
	0x41, 0x53, 0x43, 0x49, 0x49, 0x00, 0x00, 0x00 // "ASCII\0\0\0"
	};

	// Remove an existing EXIF entry from \|exifData\| if it exists. This is useful
	// when replacing existing data, it's easier to just remove the data and
	// re-allocate it than to adjust the amount of allocated data.
	static void removeExistingEntry(ExifData* exifData, ExifIfd ifd, int tag) {
	ExifEntry* entry = exif_content_get_entry(exifData->ifd[ifd],
	static_cast<ExifTag>(tag));
	if (entry) {
	exif_content_remove_entry(exifData->ifd[ifd], entry);
	}
	}

	static ExifEntry* allocateEntry(int tag,
	ExifFormat format,
	unsigned int numComponents) {
	ExifMem* mem = exif_mem_new_default();
	ExifEntry* entry = exif_entry_new_mem(mem);

	unsigned int size = numComponents * exif_format_get_size(format);
	entry->data = reinterpret_cast<unsigned char*>(exif_mem_alloc(mem, size));
	entry->size = size;
	entry->tag = static_cast<ExifTag>(tag);
	entry->components = numComponents;
	entry->format = format;

	exif_mem_unref(mem);
	return entry;
	}

	// Create an entry and place it in \|exifData\|, the entry is initialized with an
	// array of floats from \|values\|
	template<size_t N>
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	const float (&values)[N],
	float denominator = 1000.0) {
	removeExistingEntry(exifData, ifd, tag);
	ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
	ExifEntry* entry = allocateEntry(tag, EXIF_FORMAT_RATIONAL, N);
	exif_content_add_entry(exifData->ifd[ifd], entry);
	unsigned int rationalSize = exif_format_get_size(EXIF_FORMAT_RATIONAL);
	for (size_t i = 0; i < N; ++i) {
	ExifRational rational = {
	static_cast<uint32_t>(values[i] * denominator),
	static_cast<uint32_t>(denominator)
	};

	exif_set_rational(&entry->data[i * rationalSize], byteOrder, rational);
	}

	// Unref entry after changing owner to the ExifData struct
	exif_entry_unref(entry);
	return true;
	}

	// Create an entry with a single float \|value\| in it and place it in \|exifData\|
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	const float value,
	float denominator = 1000.0) {
	float values[1] = { value };
	// Recycling functions is good for the environment
	return createEntry(exifData, ifd, tag, values, denominator);
	}

	// Create an entry and place it in \|exifData\|, the entry contains the raw data
	// pointed to by \|data\| of length \|size\|.
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	const unsigned char* data,
	size_t size,
	ExifFormat format = EXIF_FORMAT_UNDEFINED) {
	removeExistingEntry(exifData, ifd, tag);
	ExifEntry* entry = allocateEntry(tag, format, size);
	memcpy(entry->data, data, size);
	exif_content_add_entry(exifData->ifd[ifd], entry);
	// Unref entry after changing owner to the ExifData struct
	exif_entry_unref(entry);
	return true;
	}

	// Create an entry and place it in \|exifData\|, the entry is initialized with
	// the string provided in \|value\|
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	const char* value) {
	unsigned int length = strlen(value) + 1;
	const unsigned char* data = reinterpret_cast<const unsigned char*>(value);
	return createEntry(exifData, ifd, tag, data, length, EXIF_FORMAT_ASCII);
	}

	// Create an entry and place it in \|exifData\|, the entry is initialized with a
	// single byte in \|value\|
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	uint8_t value) {
	return createEntry(exifData, ifd, tag, &value, 1, EXIF_FORMAT_BYTE);
	}

	// Create an entry and place it in \|exifData\|, the entry is default initialized
	// by the exif library based on \|tag\|
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag) {
	removeExistingEntry(exifData, ifd, tag);
	ExifEntry* entry = exif_entry_new();
	exif_content_add_entry(exifData->ifd[ifd], entry);
	exif_entry_initialize(entry, static_cast<ExifTag>(tag));
	// Unref entry after changing owner to the ExifData struct
	exif_entry_unref(entry);
	return true;
	}

	// Create an entry with a single EXIF LONG (32-bit value) and place it in
	// \|exifData\|.
	static bool createEntry(ExifData* exifData,
	ExifIfd ifd,
	int tag,
	int value) {
	removeExistingEntry(exifData, ifd, tag);
	ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
	ExifEntry* entry = allocateEntry(tag, EXIF_FORMAT_LONG, 1);
	exif_content_add_entry(exifData->ifd[ifd], entry);
	exif_set_long(entry->data, byteOrder, value);

	// Unref entry after changing owner to the ExifData struct
	exif_entry_unref(entry);
	return true;
	}

	static bool getCameraParam(const CameraParameters& parameters,
	const char* parameterKey,
	const char** outValue) {
	const char* value = parameters.get(parameterKey);
	if (value) {
	*outValue = value;
	return true;
	}
	return false;
	}

	static bool getCameraParam(const CameraParameters& parameters,
	const char* parameterKey,
	float* outValue) {
	const char* value = parameters.get(parameterKey);
	if (value) {
	*outValue = parameters.getFloat(parameterKey);
	return true;
	}
	return false;
	}

	static bool getCameraParam(const CameraParameters& parameters,
	const char* parameterKey,
	int64_t* outValue) {
	const char* value = parameters.get(parameterKey);
	if (value) {
	char dummy = 0;
	// Attempt to scan an extra character and then make sure it was not
	// scanned by checking that the return value indicates only one item.
	// This way we fail on any trailing characters
	if (sscanf(value, "%" SCNd64 "%c", outValue, &dummy) == 1) {
	return true;
	}
	}
	return false;
	}

	// Convert a GPS coordinate represented as a decimal degree value to sexagesimal
	// GPS coordinates comprised of <degrees> <minutes>' <seconds>"
	static void convertGpsCoordinate(float degrees, float (*result)[3]) {
	float absDegrees = fabs(degrees);
	// First value is degrees without any decimal digits
	(*result)[0] = floor(absDegrees);

	// Subtract degrees so we only have the fraction left, then multiply by
	// 60 to get the minutes
	float minutes = (absDegrees - (result)[0]) 60.0f;
	(*result)[1] = floor(minutes);

	// Same thing for seconds but here we store seconds with the fraction
	float seconds = (minutes - (result)[1]) 60.0f;
	(*result)[2] = seconds;
	}

	// Convert a UNIX epoch timestamp to a timestamp comprised of three floats for
	// hour, minute and second, and a date part that is represented as a string.
	static bool convertTimestampToTimeAndDate(int64_t timestamp,
	float (*timeValues)[3],
	std::string* date) {
	Timestamp time = timestamp;
	struct tm utcTime;
	if (TIMESTAMP_TO_TM(&time, &utcTime) == nullptr) {
	ALOGE("Could not decompose timestamp into components");
	return false;
	}
	(*timeValues)[0] = utcTime.tm_hour;
	(*timeValues)[1] = utcTime.tm_min;
	(*timeValues)[2] = utcTime.tm_sec;

	char buffer[64] = {};
	if (strftime(buffer, sizeof(buffer), "%Y:%m:%d", &utcTime) == 0) {
	ALOGE("Could not construct date string from timestamp");
	return false;
	}
	*date = buffer;
	return true;
	}

	ExifData* createExifData(const CameraParameters& params) {
	ExifData* exifData = exif_data_new();

	exif_data_set_option(exifData, EXIF_DATA_OPTION_FOLLOW_SPECIFICATION);
	exif_data_set_data_type(exifData, EXIF_DATA_TYPE_COMPRESSED);
	exif_data_set_byte_order(exifData, EXIF_BYTE_ORDER_INTEL);

	// Create mandatory exif fields and set their default values
	exif_data_fix(exifData);

	float triplet[3];
	float floatValue = 0.0f;
	const char* stringValue;
	int64_t degrees;

	// Datetime, creating and initializing a datetime tag will automatically
	// set the current date and time in the tag so just do that.
	createEntry(exifData, EXIF_IFD_0, EXIF_TAG_DATE_TIME);

	// Make and model
	createEntry(exifData, EXIF_IFD_0, EXIF_TAG_MAKE, "Emulator-Cuttlefish");
	createEntry(exifData, EXIF_IFD_0, EXIF_TAG_MODEL, "Emulator-Cuttlefish");

	// Picture size
	int width = -1, height = -1;
	params.getPictureSize(&width, &height);
	if (width >= 0 && height >= 0) {
	createEntry(exifData, EXIF_IFD_EXIF,
	EXIF_TAG_PIXEL_X_DIMENSION, width);
	createEntry(exifData, EXIF_IFD_EXIF,
	EXIF_TAG_PIXEL_Y_DIMENSION, height);
	}
	// Orientation
	if (getCameraParam(params,
	CameraParameters::KEY_ROTATION,
	&degrees)) {
	// Exif orientation values, please refer to
	// http://www.exif.org/Exif2-2.PDF, Section 4.6.4-A-Orientation
	// Or these websites:
	// http://sylvana.net/jpegcrop/exif_orientation.html
	// http://www.impulseadventure.com/photo/exif-orientation.html
	enum {
	EXIF_ROTATE_CAMERA_CW0 = 1,
	EXIF_ROTATE_CAMERA_CW90 = 6,
	EXIF_ROTATE_CAMERA_CW180 = 3,
	EXIF_ROTATE_CAMERA_CW270 = 8,
	};
	uint16_t exifOrien = 1;
	switch (degrees) {
	case 0:
	exifOrien = EXIF_ROTATE_CAMERA_CW0;
	break;
	case 90:
	exifOrien = EXIF_ROTATE_CAMERA_CW90;
	break;
	case 180:
	exifOrien = EXIF_ROTATE_CAMERA_CW180;
	break;
	case 270:
	exifOrien = EXIF_ROTATE_CAMERA_CW270;
	break;
	}
	createEntry(exifData, EXIF_IFD_0, EXIF_TAG_ORIENTATION, exifOrien);
	}
	// Focal length
	if (getCameraParam(params,
	CameraParameters::KEY_FOCAL_LENGTH,
	&floatValue)) {
	createEntry(exifData, EXIF_IFD_EXIF, EXIF_TAG_FOCAL_LENGTH, floatValue);
	}
	// GPS latitude and reference, reference indicates sign, store unsigned
	if (getCameraParam(params,
	CameraParameters::KEY_GPS_LATITUDE,
	&floatValue)) {
	convertGpsCoordinate(floatValue, &triplet);
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LATITUDE, triplet);

	const char* ref = floatValue < 0.0f ? "S" : "N";
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LATITUDE_REF, ref);
	}
	// GPS longitude and reference, reference indicates sign, store unsigned
	if (getCameraParam(params,
	CameraParameters::KEY_GPS_LONGITUDE,
	&floatValue)) {
	convertGpsCoordinate(floatValue, &triplet);
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LONGITUDE, triplet);

	const char* ref = floatValue < 0.0f ? "W" : "E";
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_LONGITUDE_REF, ref);
	}
	// GPS altitude and reference, reference indicates sign, store unsigned
	if (getCameraParam(params,
	CameraParameters::KEY_GPS_ALTITUDE,
	&floatValue)) {
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_ALTITUDE,
	static_cast<float>(fabs(floatValue)));

	// 1 indicated below sea level, 0 indicates above sea level
	uint8_t ref = floatValue < 0.0f ? 1 : 0;
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_ALTITUDE_REF, ref);
	}
	// GPS timestamp and datestamp
	int64_t timestamp = 0;
	if (getCameraParam(params,
	CameraParameters::KEY_GPS_TIMESTAMP,
	&timestamp)) {
	std::string date;
	if (convertTimestampToTimeAndDate(timestamp, &triplet, &date)) {
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_TIME_STAMP,
	triplet, 1.0f);
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_DATE_STAMP,
	date.c_str());
	}
	}

	// GPS processing method
	if (getCameraParam(params,
	CameraParameters::KEY_GPS_PROCESSING_METHOD,
	&stringValue)) {
	std::vector<unsigned char> data;
	// Because this is a tag with an undefined format it has to be prefixed
	// with the encoding type. Insert an ASCII prefix first, then the
	// actual string. Undefined tags do not have to be null terminated.
	data.insert(data.end(),
	std::begin(kAsciiPrefix),
	std::end(kAsciiPrefix));
	data.insert(data.end(), stringValue, stringValue + strlen(stringValue));
	createEntry(exifData, EXIF_IFD_GPS, EXIF_TAG_GPS_PROCESSING_METHOD,
	&data[0], data.size());
	}

	return exifData;
	}

	void freeExifData(ExifData* exifData) {
	exif_data_free(exifData);
	}

	} // namespace android