[PATCH v1] gstreamer: Use `Control<>` objects when setting controls

[Laurent Pinchart]

Hi Barnabás,

Thank you for the patch.

On Fri, Mar 28, 2025 at 05:07:36PM +0100, Barnabás Pőcze wrote:
> `g_value_get_boolean()` returns `gboolean`, which is actually `int`. Thus
> 
>   // ControlValue x;
>   auto val = g_value_get_boolean(...);
>   x.set(val);
> 
> will cause `ControlValue::set<int, ...>(const int&)` to be called, which
> will save the value as `ControlTypeInteger32`, not `ControlTypeBoolean`.

Oops... good catch !

> Then, if something tries to retrieve the boolean value, it will run into an
> assertion failure:
> 
>   Assertion `type_ == details::control_type<std::remove_cv_t<T>>::value' failed.
> 
> in `ControlValue::set()`.
> 
> Fix this by using the appropriately typed `Control<>` object when setting
> the value in the `ControlList` as this ensures that the value will be
> converted to the actual type of the control.
> 
> Bug: https://bugs.libcamera.org/show_bug.cgi?id=261
> Signed-off-by: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>
> ---
> There is a simpler fix to this issue as well:
> 
> 	diff --git a/src/gstreamer/gstlibcamera-controls.cpp.in b/src/gstreamer/gstlibcamera-controls.cpp.in
> 	index d937b19e6..8378b5fd0 100644
> 	--- a/src/gstreamer/gstlibcamera-controls.cpp.in
> 	+++ b/src/gstreamer/gstlibcamera-controls.cpp.in
> 	@@ -271,7 +271,7 @@ bool GstCameraControls::setProperty(guint propId, const GValue *value,
> 			}
> 			Rectangle val = value_get_rectangle(value);
> 	{%- else %}
> 	-               auto val = g_value_get_{{ ctrl.gtype }}(value);
> 	+               {{ ctrl.element_type }} val = g_value_get_{{ ctrl.gtype }}(value);

I knew auto was bad :-D

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

You fixed the bug even before I had a chance to look at the bug report.
Kudos !

> 	{%- endif %}
> 			control.set(val);
> 	{%- endif %}
> 
> ---
>  src/gstreamer/gstlibcamera-controls.cpp.in | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/src/gstreamer/gstlibcamera-controls.cpp.in b/src/gstreamer/gstlibcamera-controls.cpp.in
> index d937b19e6..89c530da0 100644
> --- a/src/gstreamer/gstlibcamera-controls.cpp.in
> +++ b/src/gstreamer/gstlibcamera-controls.cpp.in
> @@ -223,7 +223,6 @@ bool GstCameraControls::setProperty(guint propId, const GValue *value,
>  {%- for ctrl in ctrls %}
> 
>  	case controls::{{ ctrl.namespace }}{{ ctrl.name|snake_case|upper }}: {
> -		ControlValue control;
>  {%- if ctrl.is_array %}
>  		size_t size = gst_value_array_get_size(value);
>  {%- if ctrl.size != 0 %}
> @@ -254,12 +253,9 @@ bool GstCameraControls::setProperty(guint propId, const GValue *value,
>  		}
> 
>  {%- if ctrl.size == 0 %}
> -		control.set(Span<const {{ ctrl.element_type }}>(values.data(),
> -								size));
> +		Span<const {{ ctrl.element_type }}> val(values.data(), size);
>  {%- else %}
> -		control.set(Span<const {{ ctrl.element_type }},
> -			         {{ ctrl.size }}>(values.data(),
> -						  {{ ctrl.size }}));
> +		Span<const {{ ctrl.element_type }}, {{ ctrl.size }}> val(values.data(), size);
>  {%- endif %}
>  {%- else %}
>  {%- if ctrl.is_rectangle %}
> @@ -273,10 +269,9 @@ bool GstCameraControls::setProperty(guint propId, const GValue *value,
>  {%- else %}
>  		auto val = g_value_get_{{ ctrl.gtype }}(value);
>  {%- endif %}
> -		control.set(val);
>  {%- endif %}
> -		controls_.set(propId, control);
> -		controls_acc_.set(propId, control);
> +		controls_.set(controls::{{ ctrl.namespace }}{{ ctrl.name }}, val);
> +		controls_acc_.set(controls::{{ ctrl.namespace }}{{ ctrl.name }}, val);
>  		return true;
>  	}
>  {%- endfor %}

-- 
Regards,

Laurent Pinchart