[PATCH v3 2/3] libcamera: Add face detection controls

[Harvey Yang]

From: Yudhistira Erlandinata <yerlandinata at chromium.org>

Add FaceDetectMode, FaceDetectFaceRectangles, FaceDetectFaceScores,
and FaceDetectFaceLandmark. Also add ControlTypePoint for supporting
FaceDetectFaceLandmark.

Signed-off-by: Yudhistira Erlandinata <yerlandinata at chromium.org>
Co-developed-by: becker hsieh <beckerh at chromium.org>
Co-developed-by: Harvey Yang <chenghaoyang at chromium.org>
---
 include/libcamera/controls.h         |  6 +++
 src/libcamera/control_ids_draft.yaml | 63 ++++++++++++++++++++++++++++
 src/libcamera/controls.cpp           |  6 +++
 3 files changed, 75 insertions(+)

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index 7c2bb2872..bf1b8609c 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -34,6 +34,7 @@ enum ControlType {
 	ControlTypeString,
 	ControlTypeRectangle,
 	ControlTypeSize,
+	ControlTypePoint,
 };
 
 namespace details {
@@ -87,6 +88,11 @@ struct control_type<Size> {
 	static constexpr ControlType value = ControlTypeSize;
 };
 
+template<>
+struct control_type<Point> {
+	static constexpr ControlType value = ControlTypePoint;
+};
+
 template<typename T, std::size_t N>
 struct control_type<Span<T, N>> : public control_type<std::remove_cv_t<T>> {
 };
diff --git a/src/libcamera/control_ids_draft.yaml b/src/libcamera/control_ids_draft.yaml
index 9bef5bf15..23e09bff8 100644
--- a/src/libcamera/control_ids_draft.yaml
+++ b/src/libcamera/control_ids_draft.yaml
@@ -227,4 +227,67 @@ controls:
             value. All of the custom test patterns will be static (that is the
             raw image must not vary from frame to frame).
 
+  - FaceDetectMode:
+      type: uint8_t
+      description: |
+        Reporting mode of face detection.
+
+      enum:
+        - name: FaceDetectModeOff
+          value: 0
+          description: |
+            Pipeline should not report face detection result.
+        - name: FaceDetectModeSimple
+          value: 1
+          description: |
+            Pipeline should at least report faces boundary rectangles, in
+            metadata FaceDetectFaceRectangles, and confidence score,
+            in metadata FaceDetectFaceScores, for each of them.
+            FaceDetectFaceLandmark is optional.
+
+            The number of faces in each list must be the same.
+
+            \sa FaceDetectFaceRectangles
+            \sa FaceDetectFaceScores
+            \sa FaceDetectFaceLandmark
+
+  - FaceDetectFaceRectangles:
+      type: Rectangle
+      description: |
+        Boundary rectangle of the detected faces in format:
+        [..., xmin_i, ymin_i, xmax_i, ymax_i, ...], where (0,0) is top-left
+        of active pixel area.
+        The number of values should be 3 * the number of faces.
+
+        The FaceDetectFaceRectangles control can only be returned in metadata.
+
+      size: [n]
+
+  - FaceDetectFaceScores:
+      type: uint8_t
+      description: |
+        Confidence score of each of the detected faces by face detector.
+        The range of score is [0, 100].
+        The FaceDetectFaceScores control can only be returned in metadata.
+        The number of values should be the number of faces.
+
+        Currently identical to ANDROID_STATISTICS_FACE_SCORES.
+
+      size: [n]
+
+  - FaceDetectFaceLandmark:
+      type: Point
+      description: |
+        Array of human face landmark coordinates in format:
+        [..., left_eye_i, right_eye_i, mouth_i, left_eye_i+1, ...],
+        with i = index of face.
+        The number of values should be 6 * the number of faces.
+
+        The FaceDetectFaceLandmark control can only be returned in metadata.
+
+        Currently identical to ANDROID_STATISTICS_FACE_LANDMARKS.
+
+      size: [n]
+
+
 ...
diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
index 11d35321c..ce73ae9d7 100644
--- a/src/libcamera/controls.cpp
+++ b/src/libcamera/controls.cpp
@@ -61,6 +61,7 @@ static constexpr size_t ControlValueSize[] = {
 	[ControlTypeString]		= sizeof(char),
 	[ControlTypeRectangle]		= sizeof(Rectangle),
 	[ControlTypeSize]		= sizeof(Size),
+	[ControlTypePoint]		= sizeof(Point),
 };
 
 } /* namespace */
@@ -255,6 +256,11 @@ std::string ControlValue::toString() const
 			str += value->toString();
 			break;
 		}
+		case ControlTypePoint: {
+			const Point *value = reinterpret_cast<const Point *>(data);
+			str += value->toString();
+			break;
+		}
 		case ControlTypeNone:
 		case ControlTypeString:
 			break;
-- 
2.46.0.469.g59c65b2a67-goog