Image Capture: wire |exposureCompensation| in Linux/CrOs

media/capture/video/linux/v4l2_capture_delegate.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/capture/video/linux/v4l2_capture_delegate.h"
 
 #include <linux/version.h>
 #include <linux/videodev2.h>
 #include <poll.h>
 #include <sys/fcntl.h>
@@ skipping 576 matching lines @@
   v4l2_control exposure_current = {};
   exposure_current.id = V4L2_CID_EXPOSURE_AUTO;
   if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_G_CTRL, &exposure_current)) >=
       0) {
     photo_capabilities->current_exposure_mode =
         exposure_current.value == V4L2_EXPOSURE_MANUAL
             ? MeteringMode::MANUAL
             : MeteringMode::CONTINUOUS;
   }
 
+  photo_capabilities->exposure_compensation =
+      RetrieveUserControlRange(device_fd_.get(), V4L2_CID_EXPOSURE_ABSOLUTE);
+
   photo_capabilities->color_temperature = RetrieveUserControlRange(
       device_fd_.get(), V4L2_CID_WHITE_BALANCE_TEMPERATURE);
   if (photo_capabilities->color_temperature) {
     photo_capabilities->supported_white_balance_modes.push_back(
         MeteringMode::MANUAL);
   }
 
   v4l2_queryctrl white_balance_ctrl = {};
   white_balance_ctrl.id = V4L2_CID_AUTO_WHITE_BALANCE;
   if (RunIoctl(device_fd_.get(), VIDIOC_QUERYCTRL, &white_balance_ctrl)) {
@@ skipping 11 matching lines @@
                                     : MeteringMode::MANUAL;
   }
 
   photo_capabilities->iso = mojom::Range::New();
   photo_capabilities->height = mojom::Range::New(
       capture_format_.frame_size.height(), capture_format_.frame_size.height(),
       capture_format_.frame_size.height(), 0 /* step */);
   photo_capabilities->width = mojom::Range::New(
       capture_format_.frame_size.width(), capture_format_.frame_size.width(),
       capture_format_.frame_size.width(), 0 /* step */);
-  photo_capabilities->exposure_compensation = mojom::Range::New();
   photo_capabilities->red_eye_reduction = mojom::RedEyeReduction::NEVER;
   photo_capabilities->torch = false;
 
   photo_capabilities->brightness =
       RetrieveUserControlRange(device_fd_.get(), V4L2_CID_BRIGHTNESS);
   photo_capabilities->contrast =
       RetrieveUserControlRange(device_fd_.get(), V4L2_CID_CONTRAST);
   photo_capabilities->saturation =
       RetrieveUserControlRange(device_fd_.get(), V4L2_CID_SATURATION);
   photo_capabilities->sharpness =
@@ skipping 20 matching lines @@
   if (settings->has_white_balance_mode &&
       (settings->white_balance_mode == mojom::MeteringMode::CONTINUOUS ||
        settings->white_balance_mode == mojom::MeteringMode::MANUAL)) {
     v4l2_control white_balance_set = {};
     white_balance_set.id = V4L2_CID_AUTO_WHITE_BALANCE;
     white_balance_set.value =
         settings->white_balance_mode == mojom::MeteringMode::CONTINUOUS;
     HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &white_balance_set));
   }
 
-  // Color temperature can only be applied if Auto White Balance is off.
   if (settings->has_color_temperature) {
     v4l2_control auto_white_balance_current = {};
     auto_white_balance_current.id = V4L2_CID_AUTO_WHITE_BALANCE;
     const int result = HANDLE_EINTR(
         ioctl(device_fd_.get(), VIDIOC_G_CTRL, &auto_white_balance_current));
+    // Color temperature can only be applied if Auto White Balance is off.
     if (result >= 0 && !auto_white_balance_current.value) {
       v4l2_control set_temperature = {};
       set_temperature.id = V4L2_CID_WHITE_BALANCE_TEMPERATURE;
       set_temperature.value = settings->color_temperature;
       HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &set_temperature));
     }
   }
 
+  if (settings->has_exposure_mode &&
+      (settings->exposure_mode == mojom::MeteringMode::CONTINUOUS ||
+       settings->exposure_mode == mojom::MeteringMode::MANUAL)) {
+    v4l2_control exposure_mode_set = {};
+    exposure_mode_set.id = V4L2_CID_EXPOSURE_AUTO;
+    exposure_mode_set.value =
+        settings->exposure_mode == mojom::MeteringMode::CONTINUOUS
+            ? V4L2_EXPOSURE_APERTURE_PRIORITY
+            : V4L2_EXPOSURE_MANUAL;
+    HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &exposure_mode_set));
+  }
+
+  if (settings->has_exposure_compensation) {
+    v4l2_control auto_exposure_current = {};
+    auto_exposure_current.id = V4L2_CID_EXPOSURE_AUTO;
+    const int result = HANDLE_EINTR(
+        ioctl(device_fd_.get(), VIDIOC_G_CTRL, &auto_exposure_current));
+    // Exposure Compensation can only be applied if Auto Exposure is off.
+    if (result >= 0 && auto_exposure_current.value == V4L2_EXPOSURE_MANUAL) {
+      v4l2_control set_exposure = {};
+      set_exposure.id = V4L2_CID_EXPOSURE_ABSOLUTE;
+      set_exposure.value = settings->exposure_compensation;
+      HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &set_exposure));
+    }
+  }
+
   if (settings->has_brightness) {
     v4l2_control current = {};
     current.id = V4L2_CID_BRIGHTNESS;
     current.value = settings->brightness;
     if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &current)) < 0)
       DPLOG(ERROR) << "setting brightness to " << settings->brightness;
   }
   if (settings->has_contrast) {
     v4l2_control current = {};
     current.id = V4L2_CID_CONTRAST;
@@ skipping 161 matching lines @@
     DLOG(ERROR) << "Error mmap()ing a V4L2 buffer into userspace";
     return false;
   }
   start_ = static_cast<uint8_t*>(start);
   length_ = buffer.length;
   payload_size_ = 0;
   return true;
 }
 
 }  // namespace media