added example on how to add a queue callback

docs/source/samples/queue_add_callback.rst

@@ -0,0 +1,39 @@
+Queue add callback
+==================
+
+This example shows how to use queue callbacks. It sends both mono frames and color frames from the device to the
+host via one :code:`XLinkOut` node. In the callback function :code:`newFrame()` we decode from which camera did
+the frame come from so we can later show the frame with correct title to the user.
+
+Demo
+####
+
+.. image:: https://user-images.githubusercontent.com/18037362/120119546-309d5200-c190-11eb-932a-8235be7a4aa1.gif
+
+Setup
+#####
+
+.. include::  /includes/install_from_pypi.rst
+
+Source code
+###########
+
+.. tabs::
+
+    .. tab:: Python
+
+        Also `available on GitHub <https://github.com/luxonis/depthai-python/blob/main/examples/queue_add_callback.py>`__
+
+        .. literalinclude:: ../../../examples/queue_add_callback.py
+           :language: python
+           :linenos:
+
+    .. tab:: C++
+
+        Also `available on GitHub <https://github.com/luxonis/depthai-core/blob/main/examples/src/queue_add_callback.cpp>`__
+
+        .. literalinclude:: ../../../depthai-core/examples/src/queue_add_callback.cpp
+           :language: cpp
+           :linenos:
+
+.. include::  /includes/footer-short.rst

docs/source/tutorials/code_samples.rst

@@ -18,7 +18,6 @@ Code samples are used for automated testing. They are also a great starting poin
 - :ref:`RGB video` - Displays high resolution frames of the RGB camera
 - :ref:`Mono Preview` - Displays right/left mono cameras
 - :ref:`Depth Preview` - Displays colorized stereo disparity
-- :ref:`Device Queue Event` - Demonstrates how to use device queue events
 - :ref:`RGB Encoding` - Encodes RGB (1080P, 30FPS) into :code:`.h265` and saves it on the host
 - :ref:`RGB & Mono Encoding`- Encodes RGB (1080P, 30FPS) and both mono streams (720P, 30FPS) into :code:`.h265`/:code:`.h264` and saves them on the host
 - :ref:`Encoding Max Limit` - Encodes RGB (4k 25FPS) and both mono streams (720P, 25FPS) into :code:`.h265`/:code:`.h264` and saves them on the host
@@ -56,4 +55,6 @@ Code samples are used for automated testing. They are also a great starting poin
 .. rubric:: Mixed
 
 - :ref:`System information` - Displays device system information (memory/cpu usage, temperature)
-- :ref:`OpenCV support` - Demonstrates how to retrieve an image frame as an OpenCV frame
+- :ref:`OpenCV support` - Demonstrates how to retrieve an image frame as an OpenCV frame
+- :ref:`Device Queue Event` - Demonstrates how to use device queue events
+- :ref:`Queue add callback` - Demonstrates how to use queue callbacks

docs/source/tutorials/mixed_samples.rst

@@ -8,6 +8,10 @@ Mixed
 
    ../samples/system_information.rst
    ../samples/opencv_support.rst
+   ../samples/device_queue_event.rst
+   ../samples/queue_add_callback.rst
 
 - :ref:`System information` - Displays device system information (memory/cpu usage, temperature)
-- :ref:`OpenCV support` - Demonstrates how to retrieve an image frame as an OpenCV frame
+- :ref:`OpenCV support` - Demonstrates how to retrieve an image frame as an OpenCV frame
+- :ref:`Device Queue Event` - Demonstrates how to use device queue events
+- :ref:`Queue add callback` - Demonstrates how to use queue callbacks

docs/source/tutorials/simple_samples.rst

@@ -10,7 +10,6 @@ Simple
    ../samples/rgb_video.rst
    ../samples/mono_preview.rst
    ../samples/depth_preview.rst
-   ../samples/device_queue_event.rst
    ../samples/rgb_encoding.rst
    ../samples/rgb_mono_encoding.rst
    ../samples/encoding_max_limit.rst
@@ -27,7 +26,6 @@ These samples are great starting point for the gen2 API.
 - :ref:`RGB video` - Displays high resolution frames of the RGB camera
 - :ref:`Mono Preview` - Displays right/left mono cameras
 - :ref:`Depth Preview` - Displays colorized stereo disparity
-- :ref:`Device Queue Event` - Demonstrates how to use device queue events
 - :ref:`RGB Encoding` - Encodes RGB (1080P, 30FPS) into :code:`.h265` and saves it on the host
 - :ref:`RGB & Mono Encoding`- Encodes RGB (1080P, 30FPS) and both mono streams (720P, 30FPS) into :code:`.h265`/:code:`.h264` and saves them on the host
 - :ref:`Encoding Max Limit` - Encodes RGB (4k 25FPS) and both mono streams (720P, 25FPS) into :code:`.h265`/:code:`.h264` and saves them on the host

examples/queue_add_callback.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+import cv2
+import depthai as dai
+import queue
+
+# Create pipeline
+pipeline = dai.Pipeline()
+
+# Add all three cameras
+camRgb = pipeline.createColorCamera()
+left = pipeline.createMonoCamera()
+right = pipeline.createMonoCamera()
+
+# Create XLink output
+xout = pipeline.createXLinkOut()
+xout.setStreamName("frames")
+
+# Properties
+camRgb.setPreviewSize(300, 300)
+left.setBoardSocket(dai.CameraBoardSocket.LEFT)
+left.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
+right.setBoardSocket(dai.CameraBoardSocket.RIGHT)
+right.setResolution(dai.MonoCameraProperties.SensorResolution.THE_400_P)
+
+# Stream all the camera streams through the same XLink node
+camRgb.preview.link(xout.input)
+left.out.link(xout.input)
+right.out.link(xout.input)
+
+q = queue.Queue()
+
+def newFrame(inFrame):
+    global q
+    # Get "stream name" from the instance number
+    num = inFrame.getInstanceNum()
+    name = "color" if num == 0 else "left" if num == 1 else "right"
+    frame = inFrame.getCvFrame()
+    # This is a different thread and you could use it to
+    # run image processing algorithms here
+    q.put({"name": name, "frame": frame})
+
+# Connect to device and start pipeline
+with dai.Device(pipeline) as device:
+
+    # Add callback to the output queue "frames" for all newly arrived frames (color, left, right)
+    device.getOutputQueue(name="frames", maxSize=4, blocking=False).addCallback(newFrame)
+
+    while True:
+        # You could also get the data as non-blocking (block=False)
+        data = q.get(block=True)
+        cv2.imshow(data["name"], data["frame"])
+
+        if cv2.waitKey(1) == ord('q'):
+            break