libcamera: stream: Expose stride value

Expose the image stride  which may be retrieved after a video device
has been configured. It may only be retrieved at that point as the
assignment of video devices takes place at this point.

In the future video devices should be assigned at configuration
validation time and the stride value retrieved at that point.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/stream.cpp

@@ -301,6 +301,19 @@ StreamConfiguration::StreamConfiguration(const StreamFormats &formats)
  * \brief Stream pixel format
  */
 
+/**
+ * \var StreamConfiguration::stride
+ * \brief Image stride for the stream, in bytes
+ *
+ * The stride value reports the number of bytes between the beginning of
+ * successive lines in an image buffer for this stream. The value is
+ * valid after successfully configuring the camera with this
+ * configuration with a call to Camera::Configure().
+ *
+ * \todo Update this value when configuration is validated instead of when
+ * the camera is configured.
+ */
+
 /**
  * \var StreamConfiguration::bufferCount
  * \brief Requested number of buffers to allocate for the stream