camera: Support exposure compensation control

This CL adds exposureCompensation MediaTrackCapabilities.

Bug: b:151048287
Test: Tested on kukui.
Change-Id: I3e80d4d953d32f2fe123d02df1383206c964a1e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2392190
Commit-Queue: Hsu Wei-Cheng <mojahsu@chromium.org>
Reviewed-by: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839094}

media/capture/video/chromeos/camera_device_delegate.cc

@@ -292,6 +292,7 @@ void CameraDeviceDelegate::AllocateAndStart(
   is_set_awb_mode_ = false;
   is_set_brightness_ = false;
   is_set_contrast_ = false;
+  is_set_exposure_compensation_ = false;
   is_set_exposure_time_ = false;
   is_set_focus_distance_ = false;
   is_set_iso_ = false;
@@ -557,6 +558,22 @@ void CameraDeviceDelegate::SetPhotoOptions(
     is_set_iso_ = false;
   }
 
+  if (settings->has_exposure_compensation) {
+    int metadata_exposure_compensation =
+        std::round(settings->exposure_compensation / ae_compensation_step_);
+    request_manager_->SetRepeatingCaptureMetadata(
+        cros::mojom::CameraMetadataTag::
+            ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION,
+        cros::mojom::EntryType::TYPE_INT32, 1,
+        to_uint8_vector(metadata_exposure_compensation));
+    is_set_exposure_compensation_ = true;
+  } else if (is_set_exposure_compensation_) {
+    request_manager_->UnsetRepeatingCaptureMetadata(
+        cros::mojom::CameraMetadataTag::
+            ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION);
+    is_set_exposure_compensation_ = false;
+  }
+
   // If there is callback of SetPhotoOptions(), the streams might being
   // reconfigured and we should notify them once the reconfiguration is done.
   auto on_reconfigured_callback = base::BindOnce(
@@ -1354,6 +1371,13 @@ void CameraDeviceDelegate::OnResultMetadataAvailable(
   if (sensitivity.size() == 1)
     result_metadata_.sensitivity = sensitivity[0];
 
+  result_metadata_.ae_compensation.reset();
+  auto ae_compensation = GetMetadataEntryAsSpan<int32_t>(
+      result_metadata,
+      cros::mojom::CameraMetadataTag::ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION);
+  if (ae_compensation.size() == 1)
+    result_metadata_.ae_compensation = ae_compensation[0];
+
   result_metadata_frame_number_ = frame_number;
   // We need to wait the new result metadata for new settings.
   if (result_metadata_frame_number_ >
@@ -1580,6 +1604,38 @@ void CameraDeviceDelegate::DoGetPhotoState(
     photo_state->iso->current = result_metadata_.sensitivity.value();
   }
 
+  auto ae_compensation_step = GetMetadataEntryAsSpan<Rational>(
+      static_metadata_,
+      cros::mojom::CameraMetadataTag::ANDROID_CONTROL_AE_COMPENSATION_STEP);
+  ae_compensation_step_ = 0.0;
+  if (ae_compensation_step.size() == 1) {
+    if (ae_compensation_step[0].numerator == 0 ||
+        ae_compensation_step[0].denominator == 0) {
+      LOG(WARNING) << "AE_COMPENSATION_STEP: numerator:"
+                   << ae_compensation_step[0].numerator
+                   << "denominator:" << ae_compensation_step[0].denominator;
+    } else {
+      ae_compensation_step_ =
+          static_cast<float>(ae_compensation_step[0].numerator) /
+          static_cast<float>(ae_compensation_step[0].denominator);
+    }
+  }
+  auto ae_compensation_range = GetMetadataEntryAsSpan<int32_t>(
+      static_metadata_,
+      cros::mojom::CameraMetadataTag::ANDROID_CONTROL_AE_COMPENSATION_RANGE);
+  if (ae_compensation_step_ != 0.0 && ae_compensation_range.size() == 2) {
+    photo_state->exposure_compensation->min =
+        ae_compensation_range[0] * ae_compensation_step_;
+    photo_state->exposure_compensation->max =
+        ae_compensation_range[1] * ae_compensation_step_;
+    photo_state->exposure_compensation->step = ae_compensation_step_;
+    if (result_metadata_.ae_compensation)
+      photo_state->exposure_compensation->current =
+          result_metadata_.ae_compensation.value() * ae_compensation_step_;
+    else
+      photo_state->exposure_compensation->current = 0;
+  }
+
   std::move(callback).Run(std::move(photo_state));
 }
 

media/capture/video/chromeos/camera_device_delegate.h

@@ -44,6 +44,7 @@ struct ResultMetadata {
   ~ResultMetadata();
 
   base::Optional<uint8_t> ae_mode;
+  base::Optional<int32_t> ae_compensation;
   base::Optional<uint8_t> af_mode;
   base::Optional<uint8_t> awb_mode;
   base::Optional<int32_t> brightness;
@@ -255,6 +256,7 @@ class CAPTURE_EXPORT CameraDeviceDelegate final
   bool is_set_awb_mode_;
   bool is_set_brightness_;
   bool is_set_contrast_;
+  bool is_set_exposure_compensation_;
   bool is_set_exposure_time_;
   bool is_set_focus_distance_;
   bool is_set_iso_;
@@ -266,6 +268,8 @@ class CAPTURE_EXPORT CameraDeviceDelegate final
 
   std::vector<base::OnceClosure> get_photo_state_queue_;
   bool use_digital_zoom_;
+  float ae_compensation_step_;
+
   // We reply GetPhotoState when |result_metadata_frame_number_| >
   // |result_metadata_frame_number_for_photo_state_|. Otherwise javascript API
   // getSettings() will get non-updated settings.

media/capture/video/chromeos/camera_metadata_utils.cc

@@ -35,6 +35,10 @@ template <>
 const cros::mojom::EntryType entry_type_of<double>::value =
     cros::mojom::EntryType::TYPE_DOUBLE;
 
+template <>
+const cros::mojom::EntryType entry_type_of<Rational>::value =
+    cros::mojom::EntryType::TYPE_RATIONAL;
+
 // TODO(shik): support TYPE_RATIONAL
 
 cros::mojom::CameraMetadataEntryPtr* GetMetadataEntry(

media/capture/video/chromeos/camera_metadata_utils.h

@@ -12,6 +12,11 @@
 
 namespace media {
 
+struct Rational {
+  int32_t numerator;
+  int32_t denominator;
+};
+
 // Helper traits for converting native types to cros::mojom::EntryType.
 template <typename T, typename Enable = void>
 struct entry_type_of {