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

[Laurent Pinchart]

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 at uajain.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at 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)

-- 
Regards,

Laurent Pinchart