[libcamera-devel] [PATCH v2] Add enable_auto_focus option to the GStreamer plugin

[Cedric Nugteren]

Cameras such as the PiCam 3 support auto-focus, but the GStreamer plugin
for libcamera does not enable auto-focus. With this patch auto-focus can
be enabled for cameras that support it. By default it is disabled, which
means default behaviour remains unchanged. For cameras that do not
support auto-focus, an error message shows up if it auto-focus is
enabled.

This was tested on cameras that do not support auto-focus (e.g. PiCam2)
and was tested on a camera that does support auto-focus (PiCam3) by
enabling it, observing auto-focus, and by disabling it or by not setting
the option, both resulting in auto-focus being disabled.

This should close https://bugs.libcamera.org/show_bug.cgi?id=188.

Signed-off-by: Cedric Nugteren <web at cedricnugteren.nl>
---
Changes since v1:
- Now re-using the GParamSpec variables instead of re-creating.
- Use bool instead of gboolean for enable_auto_focus.
- Remove changes from the reconfigure_element functions.
---
 src/gstreamer/gstlibcameraprovider.cpp | 12 +++++++++++
 src/gstreamer/gstlibcamerasrc.cpp      | 29 +++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/gstreamer/gstlibcameraprovider.cpp b/src/gstreamer/gstlibcameraprovider.cpp
index 6eb0a0eb..579cb8c0 100644
--- a/src/gstreamer/gstlibcameraprovider.cpp
+++ b/src/gstreamer/gstlibcameraprovider.cpp
@@ -31,6 +31,7 @@ GST_DEBUG_CATEGORY_STATIC(provider_debug);
 
 enum {
 	PROP_DEVICE_NAME = 1,
+	PROP_ENABLE_AUTO_FOCUS = 2,
 };
 
 #define GST_TYPE_LIBCAMERA_DEVICE gst_libcamera_device_get_type()
@@ -40,6 +41,7 @@ G_DECLARE_FINAL_TYPE(GstLibcameraDevice, gst_libcamera_device,
 struct _GstLibcameraDevice {
 	GstDevice parent;
 	gchar *name;
+	bool enable_auto_focus = false;
 };
 
 G_DEFINE_TYPE(GstLibcameraDevice, gst_libcamera_device, GST_TYPE_DEVICE)
@@ -56,6 +58,7 @@ gst_libcamera_device_create_element(GstDevice *device, const gchar *name)
 	g_assert(source);
 
 	g_object_set(source, "camera-name", GST_LIBCAMERA_DEVICE(device)->name, nullptr);
+	g_object_set(source, "enable-auto-focus", GST_LIBCAMERA_DEVICE(device)->enable_auto_focus, nullptr);
 
 	return source;
 }
@@ -82,6 +85,9 @@ gst_libcamera_device_set_property(GObject *object, guint prop_id,
 	case PROP_DEVICE_NAME:
 		device->name = g_value_dup_string(value);
 		break;
+	case PROP_ENABLE_AUTO_FOCUS:
+		device->enable_auto_focus = g_value_get_boolean(value);
+		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 		break;
@@ -121,6 +127,12 @@ gst_libcamera_device_class_init(GstLibcameraDeviceClass *klass)
 						(GParamFlags)(G_PARAM_STATIC_STRINGS | G_PARAM_WRITABLE |
 							      G_PARAM_CONSTRUCT_ONLY));
 	g_object_class_install_property(object_class, PROP_DEVICE_NAME, pspec);
+	pspec = g_param_spec_boolean("enable-auto-focus",
+	                             "Enable auto-focus",
+	                             "Enable auto-focus if set to true, "
+	                             "disable it if set to false",
+	                              FALSE, G_PARAM_WRITABLE);
+	g_object_class_install_property(object_class, PROP_ENABLE_AUTO_FOCUS, pspec);
 }
 
 static GstDevice *
diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
index a10cbd4f..b2d8456b 100644
--- a/src/gstreamer/gstlibcamerasrc.cpp
+++ b/src/gstreamer/gstlibcamerasrc.cpp
@@ -146,6 +146,7 @@ struct _GstLibcameraSrc {
 	GstTask *task;
 
 	gchar *camera_name;
+	bool enable_auto_focus = false;
 
 	GstLibcameraSrcState *state;
 	GstLibcameraAllocator *allocator;
@@ -154,7 +155,8 @@ struct _GstLibcameraSrc {
 
 enum {
 	PROP_0,
-	PROP_CAMERA_NAME
+	PROP_CAMERA_NAME,
+	PROP_ENABLE_AUTO_FOCUS,
 };
 
 G_DEFINE_TYPE_WITH_CODE(GstLibcameraSrc, gst_libcamera_src, GST_TYPE_ELEMENT,
@@ -577,6 +579,18 @@ gst_libcamera_src_task_enter(GstTask *task, [[maybe_unused]] GThread *thread,
 		gst_flow_combiner_add_pad(self->flow_combiner, srcpad);
 	}
 
+	if (self->enable_auto_focus) {
+		const ControlInfoMap &infoMap = state->cam_->controls();
+		if (infoMap.find(&controls::AfMode) != infoMap.end()) {
+			state->initControls_.set(controls::AfMode, controls::AfModeContinuous);
+		} else {
+			GST_ELEMENT_ERROR(self, RESOURCE, SETTINGS,
+				("Failed to enable auto focus"),
+				("AfMode not found in camera controls, "
+				"please retry with 'enable-auto-focus=false'"));
+		}
+	}
+
 	ret = state->cam_->start(&state->initControls_);
 	if (ret) {
 		GST_ELEMENT_ERROR(self, RESOURCE, SETTINGS,
@@ -659,6 +673,9 @@ gst_libcamera_src_set_property(GObject *object, guint prop_id,
 		g_free(self->camera_name);
 		self->camera_name = g_value_dup_string(value);
 		break;
+	case PROP_ENABLE_AUTO_FOCUS:
+		self->enable_auto_focus = g_value_get_boolean(value);
+		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 		break;
@@ -676,6 +693,9 @@ gst_libcamera_src_get_property(GObject *object, guint prop_id, GValue *value,
 	case PROP_CAMERA_NAME:
 		g_value_set_string(value, self->camera_name);
 		break;
+	case PROP_ENABLE_AUTO_FOCUS:
+		g_value_set_boolean(value, self->enable_auto_focus);
+		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 		break;
@@ -844,4 +864,11 @@ gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
 							     | G_PARAM_READWRITE
 							     | G_PARAM_STATIC_STRINGS));
 	g_object_class_install_property(object_class, PROP_CAMERA_NAME, spec);
+	spec = g_param_spec_boolean("enable-auto-focus",
+	                            "Enable auto-focus",
+	                            "Enable auto-focus if set to true, "
+	                            "disable it if set to false",
+	                             FALSE, G_PARAM_WRITABLE);
+	g_object_class_install_property(object_class, PROP_ENABLE_AUTO_FOCUS, spec);
+
 }
-- 
2.34.1