Image Capture Linux/CrOs: wire some capabilities set/get

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 <poll.h>
 #include <sys/fcntl.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
@@ skipping 312 matching lines @@
   is_capturing_ = false;
   client_.reset();
 }
 
 void V4L2CaptureDelegate::TakePhoto(
     VideoCaptureDevice::TakePhotoCallback callback) {
   DCHECK(v4l2_task_runner_->BelongsToCurrentThread());
   take_photo_callbacks_.push(std::move(callback));
 }
 
+void V4L2CaptureDelegate::GetPhotoCapabilities(
+    VideoCaptureDevice::GetPhotoCapabilitiesCallback callback) {
+  DCHECK(v4l2_task_runner_->BelongsToCurrentThread());
+
+  mojom::PhotoCapabilitiesPtr photo_capabilities =
+      mojom::PhotoCapabilities::New();
+
+  photo_capabilities->zoom = mojom::Range::New();
+  v4l2_queryctrl zoom_range = {};
+  zoom_range.id = V4L2_CID_ZOOM_ABSOLUTE;
+  zoom_range.type = V4L2_CTRL_TYPE_INTEGER;
+  if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_QUERYCTRL, &zoom_range)) >=
+      0) {
+    photo_capabilities->zoom->max = zoom_range.maximum * 100;
+    photo_capabilities->zoom->min = zoom_range.minimum * 100;
+  }

[xianglu, 2016/09/20 22:18:40]

What should be done if there is an error reading these control values?

[mcasas, 2016/09/21 22:04:58]

Nothing, l.340 initializes zoom_range.{minimum, 
maximum, current} all to zero, they'll only be updated
if the QUERYCTRL (l.344) and G_CTRL (l.351) succeed.

We could add a DLOG(ERROR), but we'd know 
anyway that the reading went wrong when seeing
(in JS or elsewhere) that the zoom min/max values
are 0.

+  v4l2_control zoom_current = {};
+  zoom_current.id = V4L2_CID_ZOOM_ABSOLUTE;
+  if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_G_CTRL, &zoom_current)) >= 0)
+    photo_capabilities->zoom->current = zoom_current.value * 100;
+
+  photo_capabilities->focus_mode = mojom::MeteringMode::NONE;
+  v4l2_control auto_focus_current = {};
+  auto_focus_current.id = V4L2_CID_FOCUS_AUTO;
+  if (HANDLE_EINTR(
+          ioctl(device_fd_.get(), VIDIOC_G_CTRL, &auto_focus_current)) >= 0) {
+    photo_capabilities->focus_mode = auto_focus_current.value
+                                         ? mojom::MeteringMode::CONTINUOUS
+                                         : mojom::MeteringMode::MANUAL;
+  }
+
+  photo_capabilities->exposure_mode = mojom::MeteringMode::NONE;
+  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->exposure_mode =
+        exposure_current.value == V4L2_EXPOSURE_MANUAL
+            ? mojom::MeteringMode::MANUAL
+            : mojom::MeteringMode::CONTINUOUS;
+  }
+
+  photo_capabilities->white_balance_mode = mojom::MeteringMode::NONE;
+  v4l2_control white_balance_current = {};
+  white_balance_current.id = V4L2_CID_AUTO_WHITE_BALANCE;
+  if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_G_CTRL,
+                         &white_balance_current)) >= 0) {
+    photo_capabilities->white_balance_mode =
+        white_balance_current.value ? mojom::MeteringMode::CONTINUOUS
+                                    : mojom::MeteringMode::MANUAL;
+  }
+
+  photo_capabilities->iso = mojom::Range::New();
+  photo_capabilities->height = mojom::Range::New();
+  photo_capabilities->width = mojom::Range::New();
+  photo_capabilities->exposure_compensation = mojom::Range::New();
+  photo_capabilities->fill_light_mode = mojom::FillLightMode::NONE;
+  photo_capabilities->red_eye_reduction = false;
+  callback.Run(std::move(photo_capabilities));
+}
+
+void V4L2CaptureDelegate::SetPhotoOptions(
+    mojom::PhotoSettingsPtr settings,
+    VideoCaptureDevice::SetPhotoOptionsCallback callback) {
+  if (settings->has_zoom) {
+    v4l2_control zoom_current = {};
+    zoom_current.id = V4L2_CID_ZOOM_ABSOLUTE;
+    zoom_current.value = settings->zoom / 100;
+    if (HANDLE_EINTR(ioctl(device_fd_.get(), VIDIOC_S_CTRL, &zoom_current)) < 0)
+      DLOG(ERROR) << "Error setting zoom value to " << settings->zoom;

[xianglu, 2016/09/20 22:18:40]

Should it be settings->zoom / 100?

[mcasas, 2016/09/21 22:04:58]

Done.

+  }
+  callback.Run(true);
+}
+
 void V4L2CaptureDelegate::SetRotation(int rotation) {
   DCHECK(v4l2_task_runner_->BelongsToCurrentThread());
   DCHECK(rotation >= 0 && rotation < 360 && rotation % 90 == 0);
   rotation_ = rotation;
 }
 
 V4L2CaptureDelegate::~V4L2CaptureDelegate() {}
 
 bool V4L2CaptureDelegate::MapAndQueueBuffer(int index) {
   v4l2_buffer buffer;
@@ skipping 167 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