From 39fb6f7d83b2a3def07304e63f9f914a18815a01 Mon Sep 17 00:00:00 2001
From: William Vinnicombe <william.vinnicombe@raspberrypi.com>
Date: Tue, 12 Dec 2023 18:24:59 +0000
Subject: [PATCH 1/2] Add stereo preview example

Add an example demonstrating the use of stride, where the stride is set
to twice the image width to allow an image from a second camera to be
copied into the empty space, creating a stereo image

Signed-off-by: William Vinnicombe <william.vinnicombe@raspberrypi.com>
---
 examples/stereo_preview.py | 69 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100755 examples/stereo_preview.py

diff --git a/examples/stereo_preview.py b/examples/stereo_preview.py
new file mode 100755
index 00000000..31243f9f
--- /dev/null
+++ b/examples/stereo_preview.py
@@ -0,0 +1,69 @@
+#!/usr/bin/python3
+
+import time
+
+from picamera2 import MappedArray, Picamera2, libcamera
+
+cam2_request = None
+
+
+def pre_callback(request):
+    # Set the size, to make preview window and MappedArray remapping work
+    request.config["main"]["size"] = full_size
+    request.stream_map["main"].configuration.size = libcamera.Size(*full_size)
+
+
+def copy_image(request):
+    global cam2_request
+    request_2 = cam2_request
+    if request_2 is None:
+        return
+    request_2.acquire()
+    # Copy second image into right hand side of main image
+    with MappedArray(request, "main") as m1, MappedArray(request_2, "main") as m2:
+        a1 = m1.array
+        a2 = m2.array
+        a1[:, -a2.shape[1]:] = a2
+    request_2.release()
+
+
+def save_request(request):
+    # Store most recent request for use by other camera
+    global cam2_request
+    if cam2_request is not None:
+        cam2_request.release()
+    request.acquire()
+    cam2_request = request
+
+
+picam2a = Picamera2(0)
+
+full_size = (1920, 1080)
+half_size = (full_size[0] // 2, full_size[1])
+# Calculate stride for full frame
+full_config = picam2a.create_preview_configuration({"size": full_size})
+picam2a.configure(full_config)
+stride = picam2a.camera_config["main"]["stride"]
+
+# Configure as half frame, with full frame stride so right side is blank
+picam2a.pre_callback = pre_callback
+picam2a.post_callback = copy_image
+main_config = picam2a.create_preview_configuration(
+    main={"size": half_size, "stride": stride},
+    controls={"ScalerCrop": (0, 0, picam2a.sensor_resolution[0], picam2a.sensor_resolution[1])}
+)
+picam2a.configure(main_config)
+picam2a.start_preview(True)
+
+# Configure as half frame normally
+picam2b = Picamera2(1)
+picam2b.post_callback = save_request
+half_config = picam2a.create_preview_configuration(
+    main={"size": half_size},
+    controls={"ScalerCrop": (0, 0, picam2a.sensor_resolution[0], picam2a.sensor_resolution[1])}
+)
+picam2b.configure(half_config)
+
+picam2a.start()
+picam2b.start()
+time.sleep(10)

From 50b4ed15e17b9d08266497bffbfb9679bc7c5e32 Mon Sep 17 00:00:00 2001
From: William Vinnicombe <william.vinnicombe@raspberrypi.com>
Date: Wed, 13 Dec 2023 17:14:28 +0000
Subject: [PATCH 2/2] Add stride test

Add a test to check the stride is being set correctly when provided in
the stream configuration

Signed-off-by: William Vinnicombe <william.vinnicombe@raspberrypi.com>
---
 tests/stride_test.py | 41 +++++++++++++++++++++++++++++++++++++++++
 tests/test_list.txt  |  1 +
 2 files changed, 42 insertions(+)
 create mode 100755 tests/stride_test.py

diff --git a/tests/stride_test.py b/tests/stride_test.py
new file mode 100755
index 00000000..b1b7e4ea
--- /dev/null
+++ b/tests/stride_test.py
@@ -0,0 +1,41 @@
+#!/usr/bin/python3
+
+import time
+
+from picamera2 import MappedArray, Picamera2, libcamera
+
+
+def pre_callback(request):
+    # Set the size, to make preview window and MappedArray remapping work
+    assert request.config["main"]["stride"] == stride
+    request.config["main"]["size"] = full_size
+    request.stream_map["main"].configuration.size = libcamera.Size(*full_size)
+
+
+def post_callback(request):
+    # Make right side grey
+    with MappedArray(request, "main") as m1:
+        a1 = m1.array
+        a1[:, -a1.shape[1] // 2:] = 70
+
+
+picam2 = Picamera2(0)
+
+full_size = (1920, 1080)
+half_size = (full_size[0] // 2, full_size[1])
+# Calculate stride for full frame
+full_config = picam2.create_preview_configuration({"size": full_size})
+picam2.configure(full_config)
+stride = picam2.camera_config["main"]["stride"]
+
+# Configure as half frame, with full frame stride so right side is blank
+picam2.pre_callback = pre_callback
+picam2.post_callback = post_callback
+main_config = picam2.create_preview_configuration(
+    main={"size": half_size, "stride": stride}
+)
+picam2.configure(main_config)
+picam2.start_preview(True)
+
+picam2.start()
+time.sleep(2)
diff --git a/tests/test_list.txt b/tests/test_list.txt
index 49f72cc2..556c4ef4 100644
--- a/tests/test_list.txt
+++ b/tests/test_list.txt
@@ -77,3 +77,4 @@ tests/qt_gl_preview_test.py
 tests/stop_slow_framerate.py
 tests/allocator_test.py
 tests/allocator_leak_test.py
+tests/stride_test.py