[libcamera-devel] [PATCH 2/4] android: jpeg: exif: Simplify setGPSDateTimestamp and setGPSDMS

[Kieran Bingham]

On 08/03/2021 10:13, Paul Elder wrote:
> Now that setRational() supports setting multiple rational values, use
> that in setGPSDateTimestamp and setGPSDMS which previously set every
> rational manually.

This feels better to me ;-)

> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>  src/android/jpeg/exif.cpp | 24 ++----------------------
>  1 file changed, 2 insertions(+), 22 deletions(-)
> 
> diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
> index e5a3e448..c8b2f072 100644
> --- a/src/android/jpeg/exif.cpp
> +++ b/src/android/jpeg/exif.cpp
> @@ -345,24 +345,13 @@ void Exif::setGPSDateTimestamp(time_t timestamp)
>  		  EXIF_FORMAT_ASCII, tsStr);
>  
>  	/* Set GPS_TIME_STAMP */
> -	ExifEntry *entry =
> -		createEntry(EXIF_IFD_GPS,
> -			    static_cast<ExifTag>(EXIF_TAG_GPS_TIME_STAMP),
> -			    EXIF_FORMAT_RATIONAL, 3, 3 * sizeof(ExifRational));
> -	if (!entry)
> -		return;
> -
>  	ExifRational ts[] = {
>  		{ static_cast<ExifLong>(tm.tm_hour), 1 },
>  		{ static_cast<ExifLong>(tm.tm_min),  1 },
>  		{ static_cast<ExifLong>(tm.tm_sec),  1 },
>  	};
>  
> -	for (int i = 0; i < 3; i++)
> -		exif_set_rational(entry->data + i * sizeof(ExifRational),
> -				  order_, ts[i]);
> -
> -	exif_entry_unref(entry);
> +	setRational(EXIF_IFD_GPS, static_cast<ExifTag>(EXIF_TAG_GPS_TIME_STAMP), 3, ts);

We're now encoding the size of these tags (EXIF_TAG_GPS_TIME_STAMP) in
our layer, where for most other tags are defined by libexif.

Given that libexif doesn't support those tags correctly it would seem,
this is fine - but perhaps we should send a patch to libexif as well.

Even if we patch libexif, we will still have to do this ourselves so no
blocker.


Also rather than hardcoding '3' should we use std::size(coords) ?

5cfbbcd20731 ("libcamera: Replace ARRAY_SIZE() with std::size()")
suggests it should be possible.


>  }
>  
>  std::tuple<int, int, int> Exif::degreesToDMS(double decimalDegrees)
> @@ -376,22 +365,13 @@ std::tuple<int, int, int> Exif::degreesToDMS(double decimalDegrees)
>  
>  void Exif::setGPSDMS(ExifIfd ifd, ExifTag tag, int deg, int min, int sec)
>  {
> -	ExifEntry *entry = createEntry(ifd, tag, EXIF_FORMAT_RATIONAL, 3,
> -				       3 * sizeof(ExifRational));
> -	if (!entry)
> -		return;
> -
>  	ExifRational coords[] = {
>  		{ static_cast<ExifLong>(deg), 1 },
>  		{ static_cast<ExifLong>(min), 1 },
>  		{ static_cast<ExifLong>(sec), 1 },
>  	};
>  
> -	for (int i = 0; i < 3; i++)
> -		exif_set_rational(entry->data + i * sizeof(ExifRational),
> -				  order_, coords[i]);
> -
> -	exif_entry_unref(entry);
> +	setRational(ifd, tag, 3, coords);


And here with std::size()

With that

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>



>  }
>  
>  /*
> 

-- 
Regards
--
Kieran