[libcamera-devel] [PATCH] 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.

Signed-off-by: Cedric Nugteren <web at cedricnugteren.nl>
---
 src/gstreamer/gstlibcameraprovider.cpp | 13 ++++++++++++
 src/gstreamer/gstlibcamerasrc.cpp      | 29 +++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/gstreamer/gstlibcameraprovider.cpp
b/src/gstreamer/gstlibcameraprovider.cpp
index 6eb0a0eb..86fa2542 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;
+ gboolean 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;
 }
@@ -68,6 +71,7 @@ gst_libcamera_device_reconfigure_element(GstDevice
*device,
  return FALSE;

  g_object_set(element, "camera-name", GST_LIBCAMERA_DEVICE(device)->name,
nullptr);
+ g_object_set(element, "enable-auto-focus",
GST_LIBCAMERA_DEVICE(device)->enable_auto_focus, nullptr);

  return TRUE;
 }
@@ -82,6 +86,9 @@ 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 +128,12 @@
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);
+ GParamSpec *spec2 = 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,
spec2);
 }

 static GstDevice *
diff --git a/src/gstreamer/gstlibcamerasrc.cpp
b/src/gstreamer/gstlibcamerasrc.cpp
index a10cbd4f..672ea38a 100644
--- a/src/gstreamer/gstlibcamerasrc.cpp
+++ b/src/gstreamer/gstlibcamerasrc.cpp
@@ -146,6 +146,7 @@ struct _GstLibcameraSrc {
  GstTask *task;

  gchar *camera_name;
+ gboolean 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);
+ GParamSpec *spec2 = 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,
spec2);
+
 }
-- 
2.34.1
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