[libcamera-devel] [RFC PATCH v4 02/21] android: metadata: Add hasEntry and entryContains

[Jacopo Mondi]

Hi Paul,

On Fri, Jul 16, 2021 at 07:56:12PM +0900, Paul Elder wrote:
> Add convenience functions for checking if the an entry is present in a

s/if the an/if an/

> CameraMetadata instance, and to check if an array entry includes a
> specific value.
>
Nice

> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
>
> ---
> New in v4
> ---
>  src/android/camera_metadata.cpp | 21 +++++++++++++++++++++
>  src/android/camera_metadata.h   |  4 ++++
>  2 files changed, 25 insertions(+)
>
> diff --git a/src/android/camera_metadata.cpp b/src/android/camera_metadata.cpp
> index 3fc7cf27..47199b68 100644
> --- a/src/android/camera_metadata.cpp
> +++ b/src/android/camera_metadata.cpp
> @@ -121,6 +121,27 @@ bool CameraMetadata::resize(size_t count, size_t size)
>  	return true;
>  }
>
> +template<> bool CameraMetadata::entryContains<uint8_t>(uint32_t tag, uint8_t value) const
> +{
> +	camera_metadata_ro_entry_t entry;
> +
> +	if (!getEntry(tag, &entry))
> +		return false;
> +

I would specialize only the part here below with spcializations of

private
        template<typename T>
        bool entryContainsOne(const camera_metadata_ro_entry_t &entry, T value) const;

To be specialized in the C++ file as
        template<>
        bool entryContainsOne<uint8_t>(const camera_metadata_ro_entry_t &entry,
                                       uint8_t value) const
        {
                for (unsigned int i = 0; i < entry.count; i++) {
                        if (entry.data.u8[i] == value)
                                return true;
                 }

                 return false;
        }

        template<>
        bool entryContainsOne<int32_t>(const camera_metadata_ro_entry_t &entry,
                                       int32_t value) const
        {
                for (unsigned int i = 0; i < entry.count; i++) {
                        if (entry.data.i32[i] == value)
                                return true;
                 }

                 return false;
        }
        ...

And keep the main function in-line as
        template<typename T>
        bool entryContains(uint32_t tag, T value) const
        {
                camera_metadata_ro_entry_t entry;
                if (!getEntry(tag, &entry))
                        return false;

                return entryContainsOne<T>(entry, value);
        }

Disclaimer: not compiled
Is it worth it  in your opinion ?


> +	for (unsigned int i = 0; i < entry.count; i++)
> +		if (entry.data.u8[i] == value)
> +			return true;

braces please if the block is two levels nested

> +
> +	return false;
> +}
> +
> +

Double empy line

> +bool CameraMetadata::hasEntry(uint32_t tag) const
> +{
> +	camera_metadata_ro_entry_t entry;
> +	return getEntry(tag, &entry);
> +}
> +
>  bool CameraMetadata::addEntry(uint32_t tag, const void *data, size_t count,
>  			      size_t elementSize)
>  {
> diff --git a/src/android/camera_metadata.h b/src/android/camera_metadata.h
> index 3b7c9e24..03b3e701 100644
> --- a/src/android/camera_metadata.h
> +++ b/src/android/camera_metadata.h
> @@ -29,6 +29,10 @@ public:
>  	bool isValid() const { return valid_; }
>  	bool getEntry(uint32_t tag, camera_metadata_ro_entry_t *entry) const;
>
> +	template<typename T> bool entryContains(uint32_t tag, T value) const;
> +
> +	bool hasEntry(uint32_t tag) const;
> +
>  	template<typename T,
>  		 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
>  	bool addEntry(uint32_t tag, const T &data)
> --
> 2.27.0
>