[PATCH] libcamera: controls: Add overwriteExisting parameter to ControlList::merge

[Umang Jain]

Hi Stefan,

Thank you for the patch.

On 29/02/24 10:27 pm, Stefan Klug wrote:
> This is useful in many cases although not included in the stl.
>
> A typical usecase would be:
> ContolList controls = getDefaults()
> controls.merge(someSpecialValues, true)
> ...
>
>
> Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> ---
>
> Hey,
>
> this is my first email patch - hurray :-)

Great !
> Cheers,
> Stefan
>
>   include/libcamera/controls.h | 2 +-
>   src/libcamera/controls.cpp   | 9 ++++++---
>   2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index cf942055..0bf778d8 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -368,7 +368,7 @@ public:
>   	std::size_t size() const { return controls_.size(); }
>   
>   	void clear() { controls_.clear(); }
> -	void merge(const ControlList &source);
> +	void merge(const ControlList &source, bool overwriteExisting = false);
>   
>   	bool contains(unsigned int id) const;
>   
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index b808116c..8ef29a96 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -910,10 +910,13 @@ ControlList::ControlList(const ControlInfoMap &infoMap,
>   /**
>    * \brief Merge the \a source into the ControlList
>    * \param[in] source The ControlList to merge into this object
> + * \param[in] overwriteExisting Control if existing elements in *this shall be
> + * overwritten
>    *
>    * Merging two control lists copies elements from the \a source and inserts
>    * them in *this. If the \a source contains elements whose key is already
> - * present in *this, then those elements are not overwritten.
> + * present in *this, then those elements are only overwritten if
> + * overwriteExisting is true.

s/overwriteExisting/\a overwriteExisting/
>    *
>    * Only control lists created from the same ControlIdMap or ControlInfoMap may
>    * be merged. Attempting to do otherwise results in undefined behaviour.
> @@ -921,7 +924,7 @@ ControlList::ControlList(const ControlInfoMap &infoMap,
>    * \todo Reimplement or implement an overloaded version which internally uses
>    * std::unordered_map::merge() and accepts a non-const argument.
>    */
> -void ControlList::merge(const ControlList &source)
> +void ControlList::merge(const ControlList &source, bool overwriteExisting)
>   {
>   	/**
>   	 * \todo ASSERT that the current and source ControlList are derived
> @@ -936,7 +939,7 @@ void ControlList::merge(const ControlList &source)
>   	 */
>   
>   	for (const auto &ctrl : source) {
> -		if (contains(ctrl.first)) {
> +		if (!overwriteExisting && contains(ctrl.first)) {

Looks good to me.

Stefan, can a small unit test can cover this as well? I see,

                 /*
                  * Create a new list with a new control and merge it 
with the
                  * existing one, verifying that the existing controls
                  * values don't get overwritten.
                  */

in test/controls/control_list.cpp, so probably worth adding this new 
behaviour as well, to that test.
>   			const ControlId *id = idmap_->at(ctrl.first);
>   			LOG(Controls, Warning)
>   				<< "Control " << id->name() << " not overwritten";