[libcamera-devel,v2,2/2] android: jpeg: exif: Set timezone information

Message ID 20200924183642.7674-3-email@uajain.com
State Accepted
Commit de20d00455fbd87815a0946eaf957a9368e72a6a
Headers show
Series
  • android: jpeg: exif: Set timezone information
Related show

Commit Message

Umang Jain Sept. 24, 2020, 6:36 p.m. UTC
The EXIF specification defines three timezone related tags namely,
OffsetTime, OffsetTimeOriginal and OffsetTimeDigitized. However,
these are not supported by libexif (as of v0.6.21) hence, carry
the tags' positional values in our implementation until we get
this support from libexif itself.

Since these tags were introduced in EXIF specification v2.31, set
the exif version number explicitly too.

Signed-off-by: Umang Jain <email@uajain.com>
---
 src/android/jpeg/exif.cpp | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Comments

Laurent Pinchart Sept. 29, 2020, 2:54 a.m. UTC | #1
Hi Umang,

Thank you for the patch.

On Fri, Sep 25, 2020 at 12:06:42AM +0530, Umang Jain wrote:
> The EXIF specification defines three timezone related tags namely,

s/timezone related/timezone-related/
s/ namely,/, namely/

> OffsetTime, OffsetTimeOriginal and OffsetTimeDigitized. However,
> these are not supported by libexif (as of v0.6.21) hence, carry
> the tags' positional values in our implementation until we get
> this support from libexif itself.
> 
> Since these tags were introduced in EXIF specification v2.31, set
> the exif version number explicitly too.
> 
> Signed-off-by: Umang Jain <email@uajain.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  src/android/jpeg/exif.cpp | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
> index a5674b3..32cf897 100644
> --- a/src/android/jpeg/exif.cpp
> +++ b/src/android/jpeg/exif.cpp
> @@ -13,6 +13,16 @@ using namespace libcamera;
>  
>  LOG_DEFINE_CATEGORY(EXIF)
>  
> +/*
> + * List of EXIF tags that we set directly because they are not supported
> + * by libexif version 0.6.21.
> + */
> +enum class _ExifTag {
> +	OFFSET_TIME              = 0x9010,
> +	OFFSET_TIME_ORIGINAL     = 0x9011,
> +	OFFSET_TIME_DIGITIZED    = 0x9012,
> +};
> +
>  /*
>   * The Exif class should be instantiated and specific properties set
>   * through the exposed public API.
> @@ -51,6 +61,9 @@ Exif::Exif()
>  	 */
>  	exif_data_set_byte_order(data_, EXIF_BYTE_ORDER_INTEL);
>  
> +	setString(EXIF_IFD_EXIF, EXIF_TAG_EXIF_VERSION,
> +		  EXIF_FORMAT_UNDEFINED, "0231");
> +
>  	/* Create the mandatory EXIF fields with default data. */
>  	exif_data_fix(data_);
>  }
> @@ -197,6 +210,22 @@ void Exif::setTimestamp(time_t timestamp)
>  	setString(EXIF_IFD_0, EXIF_TAG_DATE_TIME, EXIF_FORMAT_ASCII, ts);
>  	setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_ORIGINAL, EXIF_FORMAT_ASCII, ts);
>  	setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_DIGITIZED, EXIF_FORMAT_ASCII, ts);
> +
> +	/* Query and set timezone information if available. */
> +	int r = strftime(str, sizeof(str), "%z", &tm);
> +	if (r > 0) {
> +		std::string tz(str);
> +		tz.insert(3, 1, ':');
> +		setString(EXIF_IFD_EXIF,
> +			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME),
> +			  EXIF_FORMAT_ASCII, tz);
> +		setString(EXIF_IFD_EXIF,
> +			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME_ORIGINAL),
> +			  EXIF_FORMAT_ASCII, tz);
> +		setString(EXIF_IFD_EXIF,
> +			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME_DIGITIZED),
> +			  EXIF_FORMAT_ASCII, tz);
> +	}
>  }
>  
>  void Exif::setOrientation(int orientation)

Patch

diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
index a5674b3..32cf897 100644
--- a/src/android/jpeg/exif.cpp
+++ b/src/android/jpeg/exif.cpp
@@ -13,6 +13,16 @@  using namespace libcamera;
 
 LOG_DEFINE_CATEGORY(EXIF)
 
+/*
+ * List of EXIF tags that we set directly because they are not supported
+ * by libexif version 0.6.21.
+ */
+enum class _ExifTag {
+	OFFSET_TIME              = 0x9010,
+	OFFSET_TIME_ORIGINAL     = 0x9011,
+	OFFSET_TIME_DIGITIZED    = 0x9012,
+};
+
 /*
  * The Exif class should be instantiated and specific properties set
  * through the exposed public API.
@@ -51,6 +61,9 @@  Exif::Exif()
 	 */
 	exif_data_set_byte_order(data_, EXIF_BYTE_ORDER_INTEL);
 
+	setString(EXIF_IFD_EXIF, EXIF_TAG_EXIF_VERSION,
+		  EXIF_FORMAT_UNDEFINED, "0231");
+
 	/* Create the mandatory EXIF fields with default data. */
 	exif_data_fix(data_);
 }
@@ -197,6 +210,22 @@  void Exif::setTimestamp(time_t timestamp)
 	setString(EXIF_IFD_0, EXIF_TAG_DATE_TIME, EXIF_FORMAT_ASCII, ts);
 	setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_ORIGINAL, EXIF_FORMAT_ASCII, ts);
 	setString(EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME_DIGITIZED, EXIF_FORMAT_ASCII, ts);
+
+	/* Query and set timezone information if available. */
+	int r = strftime(str, sizeof(str), "%z", &tm);
+	if (r > 0) {
+		std::string tz(str);
+		tz.insert(3, 1, ':');
+		setString(EXIF_IFD_EXIF,
+			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME),
+			  EXIF_FORMAT_ASCII, tz);
+		setString(EXIF_IFD_EXIF,
+			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME_ORIGINAL),
+			  EXIF_FORMAT_ASCII, tz);
+		setString(EXIF_IFD_EXIF,
+			  static_cast<ExifTag>(_ExifTag::OFFSET_TIME_DIGITIZED),
+			  EXIF_FORMAT_ASCII, tz);
+	}
 }
 
 void Exif::setOrientation(int orientation)