Send commands from webcamPrivate API to the webcam via V4L2 ioctls

chrome/browser/extensions/api/webcam_private/webcam_private_api.cc

 // Copyright 2014 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 "chrome/browser/extensions/api/webcam_private/webcam_private_api.h"
 
+#include <fcntl.h>
+#include <linux/videodev2.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include "base/files/scoped_file.h"
+#include "base/posix/eintr_wrapper.h"
 #include "chrome/common/extensions/api/webcam_private.h"
 
+namespace content {
+class BrowserContext;
+} // namespace content

[tommi (sloooow) - chröme, 2014/04/23 14:40:00]

nit: 2 spaces before //
(here and throughout)

[Zachary Kuznia, 2014/04/24 00:22:13]

Done.

+
+namespace {
+
+base::ScopedFD OpenWebcam(const std::string& extension_id,

[tommi (sloooow) - chröme, 2014/04/23 14:40:00]

this seems like linux specific code.  is it supposed to work on other platforms?

Maybe this file should have a _posix postfix.

[Zachary Kuznia, 2014/04/24 00:22:13]

Changed to webcam_private_api_chromeos.cc

+                          content::BrowserContext* browser_context,
+                          const std::string& webcam_id) {
+  // TODO(zork): Get device_id from content::MediaStreamManager.
+  std::string device_id = "/dev/video0";
+
+  return base::ScopedFD(HANDLE_EINTR(open(device_id.c_str(), 0)));
+}
+
+void SetWebcamParameter(int fd, int control_id, int value) {
+  struct v4l2_control v4l2_ctrl = {control_id, value};
+  HANDLE_EINTR(ioctl(fd, VIDIOC_S_CTRL, &v4l2_ctrl));
+}
+
+bool GetWebcamParameter(int fd, int control_id, int* value) {
+  struct v4l2_control v4l2_ctrl = {control_id};
+
+  if (HANDLE_EINTR(ioctl(fd, VIDIOC_G_CTRL, &v4l2_ctrl)))
+    return false;
+
+  *value = v4l2_ctrl.value;
+  return true;
+}
+

[tommi (sloooow) - chröme, 2014/04/23 14:40:00]

only one empty line

[Zachary Kuznia, 2014/04/24 00:22:13]

Done.

+
+const char kUnknownWebcam[] = "Unknown webcam id";
+} // namespace
+
 namespace extensions {
 
 WebcamPrivateSetFunction::WebcamPrivateSetFunction() {
 }
 
 WebcamPrivateSetFunction::~WebcamPrivateSetFunction() {
 }
 
 bool WebcamPrivateSetFunction::RunImpl() {
   // Get parameters
   scoped_ptr<api::webcam_private::Set::Params> params(
       api::webcam_private::Set::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  // TODO(zork): Send the value to the webcam.
+  base::ScopedFD fd =
+      OpenWebcam(extension_id(), browser_context(), params->webcam_id);
+  if (!fd.is_valid()) {
+    SetError(kUnknownWebcam);
+    return false;
+  }
+
+  if (params->config.pan) {
+    SetWebcamParameter(fd.get(), V4L2_CID_PAN_ABSOLUTE,
+                       *(params->config.pan));
+  }
+
+  if (params->config.tilt) {
+    SetWebcamParameter(fd.get(), V4L2_CID_TILT_ABSOLUTE,
+                       *(params->config.tilt));
+  }
+
+  if (params->config.zoom) {
+    SetWebcamParameter(fd.get(), V4L2_CID_ZOOM_ABSOLUTE,
+                       *(params->config.zoom));
+  }
 
   return true;
 }
 
 WebcamPrivateGetFunction::WebcamPrivateGetFunction() {
 }
 
 WebcamPrivateGetFunction::~WebcamPrivateGetFunction() {
 }
 
 bool WebcamPrivateGetFunction::RunImpl() {
   // Get parameters
   scoped_ptr<api::webcam_private::Get::Params> params(
       api::webcam_private::Get::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  // TODO(zork): Get the value from the webcam.
+  base::ScopedFD fd =
+      OpenWebcam(extension_id(), browser_context(), params->webcam_id);
+  if (!fd.is_valid()) {
+    SetError(kUnknownWebcam);
+    return false;
+  }
 
-  return false;
+  api::webcam_private::WebcamConfiguration result;
+
+  int pan;
+  if (GetWebcamParameter(fd.get(), V4L2_CID_PAN_ABSOLUTE, &pan))
+    result.pan.reset(new double(pan));
+
+  int tilt;
+  if (GetWebcamParameter(fd.get(), V4L2_CID_TILT_ABSOLUTE, &tilt))
+    result.tilt.reset(new double(tilt));
+
+  int zoom;
+  if (GetWebcamParameter(fd.get(), V4L2_CID_ZOOM_ABSOLUTE, &zoom))
+    result.zoom.reset(new double(zoom));
+
+  SetResult(result.ToValue().release());
+
+  return true;
 }
 
 WebcamPrivateResetFunction::WebcamPrivateResetFunction() {
 }
 
 WebcamPrivateResetFunction::~WebcamPrivateResetFunction() {
 }
 
 bool WebcamPrivateResetFunction::RunImpl() {
   // Get parameters
   scoped_ptr<api::webcam_private::Reset::Params> params(
       api::webcam_private::Reset::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  // TODO(zork): Reset the webcam state.
+  base::ScopedFD fd =
+      OpenWebcam(extension_id(), browser_context(), params->webcam_id);
+  if (!fd.is_valid()) {
+    SetError(kUnknownWebcam);
+    return false;
+  }
+
+  if (params->config.pan) {
+    struct v4l2_control v4l2_ctrl = {V4L2_CID_PAN_RESET};
+    HANDLE_EINTR(ioctl(fd.get(), VIDIOC_S_CTRL, &v4l2_ctrl));
+  }
+
+  if (params->config.tilt) {
+    struct v4l2_control v4l2_ctrl = {V4L2_CID_TILT_RESET};
+    HANDLE_EINTR(ioctl(fd.get(), VIDIOC_S_CTRL, &v4l2_ctrl));
+  }
+
+  if (params->config.zoom) {
+    const int kDefaultZoom = 100;
+    SetWebcamParameter(fd.get(), V4L2_CID_ZOOM_ABSOLUTE, kDefaultZoom);
+  }
 
   return true;
 }
 
 }  // namespace extensions