Update constraints algorithm for video content capture.

content/renderer/media/media_stream_constraints_util_video_content.cc

 // Copyright 2017 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 "content/renderer/media/media_stream_constraints_util_video_content.h"
 
 #include <cmath>
 #include <utility>
 #include <vector>
 
 #include "content/renderer/media/media_stream_constraints_util_sets.h"
 #include "content/renderer/media/media_stream_video_source.h"
 #include "media/base/limits.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace content {
 
-// TODO(guidou): Change default width and height to larger values. See
-// http://crbug.com/257097.
-const int kDefaultScreenCastWidth = MediaStreamVideoSource::kDefaultWidth;
-const int kDefaultScreenCastHeight = MediaStreamVideoSource::kDefaultHeight;
+const int kDefaultScreenCastWidth = 2880;
+const int kDefaultScreenCastHeight = 1800;
+const double kDefaultScreenCastAspectRatio =
+    static_cast<double>(kDefaultScreenCastWidth) / kDefaultScreenCastHeight;
 const double kDefaultScreenCastFrameRate =
     MediaStreamVideoSource::kDefaultFrameRate;
 const int kMinScreenCastDimension = 1;
 const int kMaxScreenCastDimension = media::limits::kMaxDimension - 1;
 
 namespace {
 
 using Point = ResolutionSet::Point;
 using StringSet = DiscreteSet<std::string>;
 using BoolSet = DiscreteSet<bool>;
@@ skipping 184 matching lines @@
 
   // A non-universal BoolSet can have at most one element.
   return base::Optional<bool>(candidates.FirstElement());
 }
 
 VideoCaptureSettings SelectResultFromCandidates(
     const VideoContentCaptureCandidates& candidates,
     const blink::WebMediaTrackConstraintSet& basic_constraint_set) {
   std::string device_id = SelectDeviceIDFromCandidates(candidates.device_id_set,
                                                        basic_constraint_set);
+  // If a maximum width or height is explicitly given, use them as default.
+  // If only one of them is given, use the default aspect ratio to determine the
+  // other default value.
   // TODO(guidou): Use native screen-capture resolution as default.
   // http://crbug.com/257097
+  int default_height = kDefaultScreenCastHeight;
+  int default_width = kDefaultScreenCastWidth;
+  bool has_explicit_max_height =
+      candidates.resolution_set.max_height() < kMaxScreenCastDimension;
+  bool has_explicit_max_width =
+      candidates.resolution_set.max_width() < kMaxScreenCastDimension;
+  if (has_explicit_max_height && has_explicit_max_width) {
+    default_height = candidates.resolution_set.max_height();
+    default_width = candidates.resolution_set.max_width();
+  } else if (has_explicit_max_height) {
+    default_height = candidates.resolution_set.max_height();
+    default_width = static_cast<int>(
+        std::round(default_height * kDefaultScreenCastAspectRatio));
+  } else if (has_explicit_max_width) {
+    default_width = candidates.resolution_set.max_width();
+    default_height = static_cast<int>(
+        std::round(default_width / kDefaultScreenCastAspectRatio));
+  }
   media::VideoCaptureParams capture_params =
-      SelectVideoCaptureParamsFromCandidates(
-          candidates, basic_constraint_set, kDefaultScreenCastHeight,
-          kDefaultScreenCastWidth, kDefaultScreenCastFrameRate);
+      SelectVideoCaptureParamsFromCandidates(candidates, basic_constraint_set,
+                                             default_height, default_width,
+                                             kDefaultScreenCastFrameRate);
 
   base::Optional<bool> noise_reduction = SelectNoiseReductionFromCandidates(
       candidates.noise_reduction_set, basic_constraint_set);
 
   auto track_adapter_settings = SelectVideoTrackAdapterSettings(
       basic_constraint_set, candidates.resolution_set,
       candidates.frame_rate_set, capture_params.requested_format);
 
   return VideoCaptureSettings(std::move(device_id), capture_params,
                               noise_reduction, track_adapter_settings,
@@ skipping 42 matching lines @@
         candidates.Intersection(advanced_candidates);
     if (!intersection.IsEmpty())
       candidates = std::move(intersection);
   }
 
   DCHECK(!candidates.IsEmpty());
   return SelectResultFromCandidates(candidates, constraints.basic());
 }
 
 }  // namespace content