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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2021-07-23 05:08:18 +0300
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>2021-08-17 00:24:16 +0300
commit1815a0290f5136efe7b0b43222c506774e7a8e1a (patch)
tree5701807c75cf672cd03225fc3c3402ca609306e2 /Documentation
parentddd267c348b018dc330665539aa573b32c4f6b6e (diff)
Documentation: guides: pipeline-handler: Migrate to Camera::Private
Update the pipeline handler guide following the migration from the CameraData class to the Camera::Private class. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/guides/pipeline-handler.rst67
1 files changed, 34 insertions, 33 deletions
diff --git a/Documentation/guides/pipeline-handler.rst b/Documentation/guides/pipeline-handler.rst
index 5c5cf5a9..54c8e7f1 100644
--- a/Documentation/guides/pipeline-handler.rst
+++ b/Documentation/guides/pipeline-handler.rst
@@ -106,7 +106,7 @@ functionalities descibed above. Below is a brief overview of each of those:
Abstracts camera sensor handling by hiding the details of the V4L2 subdevice
kernel API and caching sensor information.
-- `CameraData <http://libcamera.org/api-html/classlibcamera_1_1CameraData.html>`_:
+- `Camera::Private <http://libcamera.org/api-html/classlibcamera_1_1Camera_1_1Private.html>`_:
Represents device-specific data a pipeline handler associates to each Camera
instance.
@@ -416,26 +416,26 @@ receivers port output.
The Pipeline Handler is responsible for defining the set of Streams associated
with the Camera.
-Each Camera has instance-specific data represented using the `CameraData`_
+Each Camera has instance-specific data represented using the `Camera::Private`_
class, which can be extended for the specific needs of the pipeline handler.
-.. _CameraData: http://libcamera.org/api-html/classlibcamera_1_1CameraData.html
+.. _Camera::Private: http://libcamera.org/api-html/classlibcamera_1_1Camera_1_1Private.html
-To support the Camera we will later register, we need to create a CameraData
+To support the Camera we will later register, we need to create a Camera::Private
class that we can implement for our specific Pipeline Handler.
-Define a new ``VividCameraData()`` class derived from ``CameraData`` by adding
-the following code before the PipelineHandlerVivid class definition where it
-will be used:
+Define a new ``VividCameraPrivate()`` class derived from ``Camera::Private`` by
+adding the following code before the PipelineHandlerVivid class definition where
+it will be used:
.. code-block:: cpp
- class VividCameraData : public CameraData
+ class VividCameraData : public Camera::Private
{
public:
VividCameraData(PipelineHandler *pipe, MediaDevice *media)
- : CameraData(pipe), media_(media), video_(nullptr)
+ : Camera::Private(pipe), media_(media), video_(nullptr)
{
}
@@ -457,17 +457,17 @@ single stream, represented by the ``VividCameraData`` class members. More
complex pipeline handlers might register cameras composed of several video
devices and sub-devices, or multiple streams per camera that represent the
several components of the image capture pipeline. You should represent all these
-components in the ``CameraData`` derived class when developing a custom
+components in the ``Camera::Private`` derived class when developing a custom
PipelineHandler.
In our example VividCameraData we implement an ``init()`` function to prepare
-the object from our PipelineHandler, however the CameraData class does not
+the object from our PipelineHandler, however the Camera::Private class does not
specify the interface for initialisation and PipelineHandlers can manage this
-based on their own needs. Derived CameraData classes are used only by their
+based on their own needs. Derived Camera::Private classes are used only by their
respective pipeline handlers.
-The CameraData class stores the context required for each camera instance and
-is usually responsible for opening all Devices used in the capture pipeline.
+The Camera::Private class stores the context required for each camera instance
+and is usually responsible for opening all Devices used in the capture pipeline.
We can now implement the ``init`` function for our example Pipeline Handler to
create a new V4L2 video device from the media entity, which we can specify using
@@ -488,11 +488,11 @@ single capture device named 'vivid-000-vid-cap' by the device.
return 0;
}
-The CameraData should be created and initialised before we move on to register a
-new Camera device so we need to construct and initialise our
+The VividCameraData should be created and initialised before we move on to
+register a new Camera device so we need to construct and initialise our
VividCameraData after we have identified our device within
PipelineHandlerVivid::match(). The VividCameraData is wrapped by a
-std::unique_ptr to help manage the lifetime of our CameraData instance.
+std::unique_ptr to help manage the lifetime of the instance.
If the camera data initialization fails, return ``false`` to indicate the
failure to the ``match()`` function and prevent retrying of the pipeline
@@ -509,9 +509,9 @@ handler.
Once the camera data has been initialized, the Camera device instances and the
associated streams have to be registered. Create a set of streams for the
camera, which for this device is only one. You create a camera using the static
-`Camera::create`_ function, passing the pipeline handler, the id of the camera,
-and the streams available. Then register the camera and its data with the
-pipeline handler and camera manager using `registerCamera`_.
+`Camera::create`_ function, passing the Camera::Private instance, the id of the
+camera, and the streams available. Then register the camera with the pipeline
+handler and camera manager using `registerCamera`_.
Finally with a successful construction, we return 'true' indicating that the
PipelineHandler successfully matched and constructed a device.
@@ -549,23 +549,24 @@ Our match function should now look like the following:
/* Create and register the camera. */
std::set<Stream *> streams{ &data->stream_ };
- std::shared_ptr<Camera> camera = Camera::create(this, data->video_->deviceName(), streams);
- registerCamera(std::move(camera), std::move(data));
+ const std::string &id = data->video_->deviceName();
+ std::shared_ptr<Camera> camera = Camera::create(data.release(), id, streams);
+ registerCamera(std::move(camera));
return true;
}
-We will need to use our custom CameraData class frequently throughout the
+We will need to use our custom VividCameraData class frequently throughout the
pipeline handler, so we add a private convenience helper to our Pipeline handler
-to obtain and cast the custom CameraData instance from a Camera instance.
+to obtain and cast the custom VividCameraData instance from a Camera::Private
+instance.
.. code-block:: cpp
private:
- VividCameraData *cameraData(const Camera *camera)
+ VividCameraData *cameraData(Camera *camera)
{
- return static_cast<VividCameraData *>(
- PipelineHandler::cameraData(camera));
+ return static_cast<VividCameraData *>(camera->_d());
}
At this point, you need to add the following new includes to provide the Camera
@@ -595,12 +596,12 @@ are defined by src/libcamera/`properties_ids.yaml`_.
Pipeline handlers can optionally register the list of controls an application
can set as well as a list of immutable camera properties. Being both
-Camera-specific values, they are represented in the ``CameraData`` base class,
-which provides two members for this purpose: the `CameraData::controlInfo_`_ and
-the `CameraData::properties_`_ fields.
+Camera-specific values, they are represented in the ``Camera::Private`` base
+class, which provides two members for this purpose: the
+`Camera::Private::controlInfo_`_ and the `Camera::Private::properties_`_ fields.
-.. _CameraData::controlInfo_: http://libcamera.org/api-html/classlibcamera_1_1CameraData.html#ab9fecd05c655df6084a2233872144a52
-.. _CameraData::properties_: http://libcamera.org/api-html/classlibcamera_1_1CameraData.html#a84002c29f45bd35566c172bb65e7ec0b
+.. _Camera::Private::controlInfo_: http://libcamera.org/api-html/classlibcamera_1_1Camera_1_1Private.html#ab4e183eb4dabe929d1b2bbbb519b969f
+.. _Camera::Private::properties_: http://libcamera.org/api-html/classlibcamera_1_1Camera_1_1Private.html#ad31f12f5ed9c1fbe25750902f4791064
The ``controlInfo_`` field represents a map of ``ControlId`` instances
associated with the limits of valid values supported for the control. More
@@ -618,7 +619,7 @@ Complete the initialization of the ``VividCameraData`` class by adding the
following code to the ``VividCameraData::init()`` function to initialise the
controls. For more complex control configurations, this could of course be
broken out to a separate function, but for now we just initialise the small set
-inline in our CameraData init:
+inline in our VividCameraData init:
.. code-block:: cpp