V4L2: avoid resetting zoom controls

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 166 matching lines @@
 // Determines if |control_id| should be skipped, https://crbug.com/697885.
 #if !defined(V4L2_CID_PAN_SPEED)
 #define V4L2_CID_PAN_SPEED (V4L2_CID_CAMERA_CLASS_BASE + 32)
 #endif
 #if !defined(V4L2_CID_TILT_SPEED)
 #define V4L2_CID_TILT_SPEED (V4L2_CID_CAMERA_CLASS_BASE + 33)
 #endif
 #if !defined(V4L2_CID_PANTILT_CMD)
 #define V4L2_CID_PANTILT_CMD (V4L2_CID_CAMERA_CLASS_BASE + 34)
 #endif
 static bool IsBlacklistedControl(int control_id) {

[Pawel Osciak, 2017/05/25 05:42:43]

Would it perhaps be possible to have this list in a common place to avoid
duplicating it here and in the test?

Or, perhaps better, call the same method in both?

[mcasas, 2017/05/26 14:25:51]

I ruled that out because, for the purpose of 
unittests, we're not supposed to use the class
under test, but instead see it as a black box.
IOW, we can't test
FunctionA() {
  return FunctionB();
}

by comparing the result of calling FunctionA()
with the result of calling FunctionB(), that's not
testing anything :-)
Instead, we test the result of calling FunctionA()
against some expectations, that are only defined
for the purpose of the test.

[Pawel Osciak, 2017/05/29 03:54:43]

Acknowledged.

   switch (control_id) {
     case V4L2_CID_PAN_RELATIVE:
     case V4L2_CID_TILT_RELATIVE:
     case V4L2_CID_PAN_RESET:
     case V4L2_CID_TILT_RESET:
     case V4L2_CID_PAN_ABSOLUTE:
     case V4L2_CID_TILT_ABSOLUTE:
+    case V4L2_CID_ZOOM_ABSOLUTE:
+    case V4L2_CID_ZOOM_RELATIVE:
+    case V4L2_CID_ZOOM_CONTINUOUS:
     case V4L2_CID_PAN_SPEED:
     case V4L2_CID_TILT_SPEED:
     case V4L2_CID_PANTILT_CMD:
       return true;
   }
   return false;
 }
 
 // Sets all user control to their default. Some controls are enabled by another
 // flag, usually having the word "auto" in the name, see IsSpecialControl().
@@ skipping 682 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