[RFC,v3,15/22] guides: application: Document Camera::metadataAvailable
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Message ID 20251030165816.1095180-16-barnabas.pocze@ideasonboard.com
State New
Headers show
Series
  • libcamera: Add `MetadataList`
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Commit Message

Barnabás Pőcze Oct. 30, 2025, 4:58 p.m. UTC 
From: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

Document the Camera::metadataAvailable signal in the application
developer guide as an opt-in feature to receive early metadata
notifications.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
---
Original: https://patchwork.libcamera.org/patch/22228/

changes in v3:
  * adjust previous paragraph about signals
---
 Documentation/guides/application-developer.rst | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

Patch
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diff --git a/Documentation/guides/application-developer.rst b/Documentation/guides/application-developer.rst
index 06c07d1e94..166919cf62 100644
--- a/Documentation/guides/application-developer.rst
+++ b/Documentation/guides/application-developer.rst
@@ -350,8 +350,17 @@  them.
 
 .. _Qt Signals and Slots: https://doc.qt.io/qt-6/signalsandslots.html
 
-The ``Camera`` device emits two signals that applications can connect to in
-order to execute callbacks on frame completion events.
+During request processing, the ``Camera`` device emits certain signals
+to notify the application about events regarding each and every request.
+These signals are described below.
+
+The ``Camera::metadataAvailable`` signal notifies applications of the
+availability of metadata results before a request completes. Receiving
+notification about metadata availability allows application to fast-track
+handling of metadata results before all the image buffers in a request are
+ready. The full list of metadata results associated with a Request is also
+available at request complete time, and receiving notifications for early
+metadata availability is an optional feature for applications.
 
 The ``Camera::bufferCompleted`` signal notifies applications that a buffer with
 image data is available. Receiving notifications about the single buffer