Add utility set classes to support getUserMedia constraint proccessing.

content/renderer/media/media_stream_constraints_util_sets.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_sets.h"
+
+#include <cmath>
+
+#include "content/renderer/media/media_stream_constraints_util.h"
+#include "content/renderer/media/media_stream_video_source.h"
+#include "third_party/WebKit/public/platform/WebMediaConstraints.h"
+
+namespace content {
+
+using Point = ResolutionSet::Point;
+
+namespace {
+
+constexpr double kTolerance = 1e-5;
+
+constexpr int kDefaultHeight = MediaStreamVideoSource::kDefaultHeight;
+constexpr int kDefaultWidth = MediaStreamVideoSource::kDefaultWidth;
+constexpr double kDefaultAspectRatio =
+    MediaStreamVideoSource::kDefaultAspectRatio;
+
+// Not perfect, but good enough for this application.
+bool AreApproximatelyEqual(double d1, double d2) {
+  if (std::fabs((d1 - d2)) <= kTolerance)
+    return true;
+
+  return d1 == d2 || (std::fabs((d1 - d2) / d1) <= kTolerance &&
+                      std::fabs((d1 - d2) / d2) <= kTolerance);
+}
+
+bool IsLess(double d1, double d2) {
+  return d1 < d2 && !AreApproximatelyEqual(d1, d2);
+}
+
+bool IsLessOrEqual(double d1, double d2) {
+  return d1 < d2 || AreApproximatelyEqual(d1, d2);
+}
+
+bool IsGreater(double d1, double d2) {
+  return d1 > d2 && !AreApproximatelyEqual(d1, d2);
+}
+
+bool IsGreaterOrEqual(double d1, double d2) {
+  return d1 > d2 || AreApproximatelyEqual(d1, d2);
+}
+
+int ToValidDimension(long dimension) {
+  if (dimension > ResolutionSet::kMaxDimension)
+    return ResolutionSet::kMaxDimension;
+  if (dimension < 0)
+    return 0;
+
+  return static_cast<int>(dimension);
+}
+
+int MinDimensionFromConstraint(const blink::LongConstraint& constraint) {
+  if (!ConstraintHasMin(constraint))
+    return 0;
+
+  return ToValidDimension(ConstraintMin(constraint));
+}
+
+int MaxDimensionFromConstraint(const blink::LongConstraint& constraint) {
+  if (!ConstraintHasMax(constraint))
+    return ResolutionSet::kMaxDimension;
+
+  return ToValidDimension(ConstraintMax(constraint));
+}
+
+double ToValidAspectRatio(double aspect_ratio) {
+  return aspect_ratio < 0.0 ? 0.0 : aspect_ratio;
+}
+
+double MinAspectRatioFromConstraint(const blink::DoubleConstraint& constraint) {
+  if (!ConstraintHasMin(constraint))
+    return 0.0;
+
+  return ToValidAspectRatio(ConstraintMin(constraint));
+}
+
+double MaxAspectRatioFromConstraint(const blink::DoubleConstraint& constraint) {
+  if (!ConstraintHasMax(constraint))
+    return HUGE_VAL;
+
+  return ToValidAspectRatio(ConstraintMax(constraint));
+}
+
+bool IsPositiveFiniteAspectRatio(double aspect_ratio) {
+  return std::isfinite(aspect_ratio) && aspect_ratio > 0.0;
+}
+
+// If |vertices| has a single element, return |vertices[0]|.
+// If |vertices| has two elements, returns the point in the segment defined by
+// |vertices| that is closest to |point|.
+// |vertices| must have 1 or 2 elements. Otherwise, behavior is undefined.
+// This function is called when |point| has already been determined to be
+// outside a polygon and |vertices| is the vertex or side closest to |point|.
+Point GetClosestPointToVertexOrSide(const std::vector<Point> vertices,
+                                    const Point& point) {
+  DCHECK(!vertices.empty());
+  // If only a single vertex closest to |point|, return that vertex.
+  if (vertices.size() == 1U)
+    return vertices[0];
+
+  DCHECK_EQ(vertices.size(), 2U);
+  // If a polygon side is closest to the ideal height, return the
+  // point with aspect ratio closest to the default.
+  return Point::ClosestPointInSegment(point, vertices[0], vertices[1]);
+}
+
+Point SelectPointWithLargestArea(const Point& p1, const Point& p2) {
+  return p1.width() * p1.height() > p2.width() * p2.height() ? p1 : p2;
+}
+
+}  // namespace
+
+Point::Point(double height, double width) : height_(height), width_(width) {
+  DCHECK(!std::isnan(height_));
+  DCHECK(!std::isnan(width_));
+}
+Point::Point(const Point& other) = default;
+Point& Point::operator=(const Point& other) = default;
+Point::~Point() = default;
+
+bool Point::operator==(const Point& other) const {
+  return height_ == other.height_ && width_ == other.width_;
+}
+
+bool Point::operator!=(const Point& other) const {
+  return !(*this == other);
+}
+
+bool Point::IsApproximatelyEqualTo(const Point& other) const {
+  return AreApproximatelyEqual(height_, other.height_) &&
+         AreApproximatelyEqual(width_, other.width_);
+}
+
+Point Point::operator+(const Point& other) const {
+  return Point(height_ + other.height_, width_ + other.width_);
+}
+
+Point Point::operator-(const Point& other) const {
+  return Point(height_ - other.height_, width_ - other.width_);
+}
+
+Point operator*(double d, const Point& p) {
+  return Point(d * p.height(), d * p.width());
+}
+
+// Returns the dot product between |p1| and |p2|.
+// static
+double Point::Dot(const Point& p1, const Point& p2) {
+  return p1.height_ * p2.height_ + p1.width_ * p2.width_;
+}
+
+// static
+double Point::SquareEuclideanDistance(const Point& p1, const Point& p2) {
+  Point diff = p1 - p2;
+  return Dot(diff, diff);
+}
+
+// static
+Point Point::ClosestPointInSegment(const Point& p,
+                                   const Point& s1,
+                                   const Point& s2) {
+  // If |s1| and |s2| are the same, it is not really a segment. The closest
+  // point to |p| is |s1|=|s2|.
+  if (s1 == s2)
+    return s1;
+
+  // Translate coordinates to a system where the origin is |s1|.
+  Point p_trans = p - s1;
+  Point s2_trans = s2 - s1;
+
+  // On this system, we are interested in the projection of |p_trans| on
+  // |s2_trans|. The projection is m * |s2_trans|, where
+  //       m = Dot(|s2_trans|, |p_trans|) / Dot(|s2_trans|, |s2_trans|).
+  // If 0 <= m <= 1, the projection falls within the segment, and the closest
+  // point is the projection itself.
+  // If m < 0, the closest point is S1.
+  // If m > 1, the closest point is S2.
+  double m = Dot(s2_trans, p_trans) / Dot(s2_trans, s2_trans);
+  if (m < 0)
+    return s1;
+  else if (m > 1)
+    return s2;
+
+  // Return the projection in the original coordinate system.
+  return s1 + m * s2_trans;
+}
+
+ResolutionSet::ResolutionSet(int min_height,
+                             int max_height,
+                             int min_width,
+                             int max_width,
+                             double min_aspect_ratio,
+                             double max_aspect_ratio)
+    : min_height_(min_height),
+      max_height_(max_height),
+      min_width_(min_width),
+      max_width_(max_width),
+      min_aspect_ratio_(min_aspect_ratio),
+      max_aspect_ratio_(max_aspect_ratio) {
+  DCHECK_GE(min_height_, 0);
+  DCHECK_GE(max_height_, 0);
+  DCHECK_LE(max_height_, kMaxDimension);
+  DCHECK_GE(min_width_, 0);
+  DCHECK_GE(max_width_, 0);
+  DCHECK_LE(max_width_, kMaxDimension);
+  DCHECK_GE(min_aspect_ratio_, 0.0);
+  DCHECK_GE(max_aspect_ratio_, 0.0);
+  DCHECK(!std::isnan(min_aspect_ratio_));
+  DCHECK(!std::isnan(max_aspect_ratio_));
+}
+
+ResolutionSet::ResolutionSet()
+    : ResolutionSet(0, kMaxDimension, 0, kMaxDimension, 0.0, HUGE_VAL) {}
+
+ResolutionSet::ResolutionSet(const ResolutionSet& other) = default;
+ResolutionSet::~ResolutionSet() = default;
+ResolutionSet& ResolutionSet::operator=(const ResolutionSet& other) = default;
+
+bool ResolutionSet::IsHeightEmpty() const {
+  return min_height_ > max_height_ || min_height_ >= kMaxDimension ||
+         max_height_ <= 0;
+}
+
+bool ResolutionSet::IsWidthEmpty() const {
+  return min_width_ > max_width_ || min_width_ >= kMaxDimension ||
+         max_width_ <= 0;
+}
+
+bool ResolutionSet::IsAspectRatioEmpty() const {
+  double max_resolution_aspect_ratio =
+      static_cast<double>(max_width_) / static_cast<double>(min_height_);
+  double min_resolution_aspect_ratio =
+      static_cast<double>(min_width_) / static_cast<double>(max_height_);
+
+  return IsGreater(min_aspect_ratio_, max_aspect_ratio_) ||
+         IsLess(max_resolution_aspect_ratio, min_aspect_ratio_) ||
+         IsGreater(min_resolution_aspect_ratio, max_aspect_ratio_) ||
+         !std::isfinite(min_aspect_ratio_) || max_aspect_ratio_ <= 0.0;
+}
+
+bool ResolutionSet::IsEmpty() const {
+  return IsHeightEmpty() || IsWidthEmpty() || IsAspectRatioEmpty();
+}
+
+bool ResolutionSet::ContainsPoint(const Point& point) const {
+  double ratio = point.AspectRatio();
+  return point.height() >= min_height_ && point.height() <= max_height_ &&
+         point.width() >= min_width_ && point.width() <= max_width_ &&
+         ((IsGreaterOrEqual(ratio, min_aspect_ratio_) &&
+           IsLessOrEqual(ratio, max_aspect_ratio_)) ||
+          // (0.0, 0.0) is always included in the aspect-ratio range.
+          (point.width() == 0.0 && point.height() == 0.0));
+}
+
+bool ResolutionSet::ContainsPoint(int height, int width) const {
+  return ContainsPoint(Point(height, width));
+}
+
+ResolutionSet ResolutionSet::Intersection(const ResolutionSet& other) const {
+  return ResolutionSet(std::max(min_height_, other.min_height_),
+                       std::min(max_height_, other.max_height_),
+                       std::max(min_width_, other.min_width_),
+                       std::min(max_width_, other.max_width_),
+                       std::max(min_aspect_ratio_, other.min_aspect_ratio_),
+                       std::min(max_aspect_ratio_, other.max_aspect_ratio_));
+}
+
+Point ResolutionSet::SelectClosestPointToIdeal(
+    const blink::WebMediaTrackConstraintSet& constraint_set) const {
+  DCHECK(!IsEmpty());
+  int num_ideals = 0;
+  if (constraint_set.height.hasIdeal())
+    ++num_ideals;
+  if (constraint_set.width.hasIdeal())
+    ++num_ideals;
+  if (constraint_set.aspectRatio.hasIdeal())
+    ++num_ideals;
+
+  switch (num_ideals) {
+    case 0:
+      return SelectClosestPointToIdealAspectRatio(kDefaultAspectRatio);
+
+    case 1:
+      // This case requires a point closest to a line.
+      // In all variants, if the ideal line intersects the polygon, select the
+      // point in the intersection that is closest to preserving the default
+      // aspect ratio or a default dimension.
+      // If the ideal line is outside the polygon, there is either a single
+      // vertex or a polygon side closest to the ideal line. If a single vertex,
+      // select that vertex. If a polygon side, select the point on that side
+      // that is closest to preserving the default aspect ratio or a default
+      // dimension.
+      if (constraint_set.height.hasIdeal()) {
+        int ideal_height = ToValidDimension(constraint_set.height.ideal());
+        ResolutionSet ideal_line = ResolutionSet::FromExactHeight(ideal_height);
+        ResolutionSet intersection = Intersection(ideal_line);
+        if (!intersection.IsEmpty()) {
+          return intersection.ClosestPointTo(
+              Point(ideal_height, ideal_height * kDefaultAspectRatio));
+        }
+        std::vector<Point> closest_vertices =
+            GetClosestVertices(&Point::height, ideal_height);
+        Point ideal_point(closest_vertices[0].height(),
+                          closest_vertices[0].height() * kDefaultAspectRatio);
+        return GetClosestPointToVertexOrSide(closest_vertices, ideal_point);
+      } else if (constraint_set.width.hasIdeal()) {
+        int ideal_width = ToValidDimension(constraint_set.width.ideal());
+        ResolutionSet ideal_line = ResolutionSet::FromExactWidth(ideal_width);
+        ResolutionSet intersection = Intersection(ideal_line);
+        if (!intersection.IsEmpty()) {
+          return intersection.ClosestPointTo(
+              Point(ideal_width / kDefaultAspectRatio, ideal_width));
+        }
+        std::vector<Point> closest_vertices =
+            GetClosestVertices(&Point::width, ideal_width);
+        Point ideal_point(closest_vertices[0].width() / kDefaultAspectRatio,
+                          closest_vertices[0].width());
+        return GetClosestPointToVertexOrSide(closest_vertices, ideal_point);
+      } else {
+        DCHECK(constraint_set.aspectRatio.hasIdeal());
+        double ideal_aspect_ratio =
+            ToValidAspectRatio(constraint_set.aspectRatio.ideal());
+        return SelectClosestPointToIdealAspectRatio(ideal_aspect_ratio);
+      }
+
+    case 2:
+    case 3:
+      double ideal_height;
+      double ideal_width;
+      if (constraint_set.height.hasIdeal()) {
+        ideal_height = ToValidDimension(constraint_set.height.ideal());
+        ideal_width =
+            constraint_set.width.hasIdeal()
+                ? ToValidDimension(constraint_set.width.ideal())
+                : ideal_height *
+                      ToValidAspectRatio(constraint_set.aspectRatio.ideal());
+      } else {
+        DCHECK(constraint_set.width.hasIdeal());
+        DCHECK(constraint_set.aspectRatio.hasIdeal());
+        ideal_width = ToValidDimension(constraint_set.width.ideal());
+        ideal_height = ideal_width /
+                       ToValidAspectRatio(constraint_set.aspectRatio.ideal());
+      }
+      return ClosestPointTo(Point(ideal_height, ideal_width));
+
+    default:
+      NOTREACHED();
+  }
+  NOTREACHED();
+  return Point(-1, -1);
+}
+
+Point ResolutionSet::SelectClosestPointToIdealAspectRatio(
+    double ideal_aspect_ratio) const {
+  ResolutionSet intersection =
+      Intersection(ResolutionSet::FromExactAspectRatio(ideal_aspect_ratio));
+  if (!intersection.IsEmpty()) {
+    Point default_height_point(kDefaultHeight,
+                               kDefaultHeight * ideal_aspect_ratio);
+    Point default_width_point(kDefaultWidth / ideal_aspect_ratio,
+                              kDefaultWidth);
+    return SelectPointWithLargestArea(
+        intersection.ClosestPointTo(default_height_point),
+        intersection.ClosestPointTo(default_width_point));
+  }
+  std::vector<Point> closest_vertices =
+      GetClosestVertices(&Point::AspectRatio, ideal_aspect_ratio);
+  double actual_aspect_ratio = closest_vertices[0].AspectRatio();
+  Point default_height_point(kDefaultHeight,
+                             kDefaultHeight * actual_aspect_ratio);
+  Point default_width_point(kDefaultWidth / actual_aspect_ratio, kDefaultWidth);
+  return SelectPointWithLargestArea(
+      GetClosestPointToVertexOrSide(closest_vertices, default_height_point),
+      GetClosestPointToVertexOrSide(closest_vertices, default_width_point));
+}
+
+Point ResolutionSet::ClosestPointTo(const Point& point) const {
+  DCHECK(std::numeric_limits<double>::has_infinity);
+
+  if (ContainsPoint(point))
+    return point;
+
+  auto vertices = ComputeVertices();
+  DCHECK_GE(vertices.size(), 1U);
+  Point best_candidate(0, 0);
+  double best_distance = HUGE_VAL;
+  for (size_t i = 0; i < vertices.size(); ++i) {
+    Point candidate = Point::ClosestPointInSegment(
+        point, vertices[i], vertices[(i + 1) % vertices.size()]);
+    double distance = Point::SquareEuclideanDistance(point, candidate);
+    if (distance < best_distance) {
+      best_candidate = candidate;
+      best_distance = distance;
+    }
+  }
+
+  DCHECK(std::isfinite(best_distance));
+  return best_candidate;
+}
+
+std::vector<Point> ResolutionSet::GetClosestVertices(double (Point::*accessor)()
+                                                         const,
+                                                     double value) const {
+  DCHECK(!IsEmpty());
+  std::vector<Point> vertices = ComputeVertices();
+  std::vector<Point> closest_vertices;
+  double best_diff = HUGE_VAL;
+  for (const auto& vertex : vertices) {
+    double diff;
+    if (std::isfinite(value))
+      diff = std::fabs((vertex.*accessor)() - value);
+    else
+      diff = (vertex.*accessor)() == value ? 0.0 : HUGE_VAL;
+    if (diff <= best_diff) {
+      if (diff < best_diff) {
+        best_diff = diff;
+        closest_vertices.clear();
+      }
+      closest_vertices.push_back(vertex);
+    }
+  }
+  DCHECK(!closest_vertices.empty());
+  DCHECK_LE(closest_vertices.size(), 2U);
+  return closest_vertices;
+}
+
+// static
+ResolutionSet ResolutionSet::FromHeight(int min, int max) {
+  return ResolutionSet(min, max, 0, kMaxDimension, 0.0, HUGE_VAL);
+}
+
+// static
+ResolutionSet ResolutionSet::FromExactHeight(int value) {
+  return ResolutionSet(value, value, 0, kMaxDimension, 0.0, HUGE_VAL);
+}
+
+// static
+ResolutionSet ResolutionSet::FromWidth(int min, int max) {
+  return ResolutionSet(0, kMaxDimension, min, max, 0.0, HUGE_VAL);
+}
+
+// static
+ResolutionSet ResolutionSet::FromExactWidth(int value) {
+  return ResolutionSet(0, kMaxDimension, value, value, 0.0, HUGE_VAL);
+}
+
+// static
+ResolutionSet ResolutionSet::FromAspectRatio(double min, double max) {
+  return ResolutionSet(0, kMaxDimension, 0, kMaxDimension, min, max);
+}
+
+// static
+ResolutionSet ResolutionSet::FromExactAspectRatio(double value) {
+  return ResolutionSet(0, kMaxDimension, 0, kMaxDimension, value, value);
+}
+
+std::vector<Point> ResolutionSet::ComputeVertices() const {
+  std::vector<Point> vertices;
+  // Add vertices in counterclockwise order
+  // Start with (min_height, min_width) and continue along min_width.
+  TryAddVertex(&vertices, Point(min_height_, min_width_));
+  if (IsPositiveFiniteAspectRatio(max_aspect_ratio_))
+    TryAddVertex(&vertices, Point(min_width_ / max_aspect_ratio_, min_width_));
+  if (IsPositiveFiniteAspectRatio(min_aspect_ratio_))
+    TryAddVertex(&vertices, Point(min_width_ / min_aspect_ratio_, min_width_));
+  TryAddVertex(&vertices, Point(max_height_, min_width_));
+  // Continue along max_height.
+  if (IsPositiveFiniteAspectRatio(min_aspect_ratio_)) {
+    TryAddVertex(&vertices,
+                 Point(max_height_, max_height_ * min_aspect_ratio_));
+  }
+  if (IsPositiveFiniteAspectRatio(max_aspect_ratio_))
+    TryAddVertex(&vertices,
+                 Point(max_height_, max_height_ * max_aspect_ratio_));
+  TryAddVertex(&vertices, Point(max_height_, max_width_));
+  // Continue along max_width.
+  if (IsPositiveFiniteAspectRatio(min_aspect_ratio_))
+    TryAddVertex(&vertices, Point(max_width_ / min_aspect_ratio_, max_width_));
+  if (IsPositiveFiniteAspectRatio(max_aspect_ratio_))
+    TryAddVertex(&vertices, Point(max_width_ / max_aspect_ratio_, max_width_));
+  TryAddVertex(&vertices, Point(min_height_, max_width_));
+  // Finish along min_height.
+  if (IsPositiveFiniteAspectRatio(max_aspect_ratio_)) {
+    TryAddVertex(&vertices,
+                 Point(min_height_, min_height_ * max_aspect_ratio_));
+  }
+  if (IsPositiveFiniteAspectRatio(min_aspect_ratio_)) {
+    TryAddVertex(&vertices,
+                 Point(min_height_, min_height_ * min_aspect_ratio_));
+  }
+
+  DCHECK_LE(vertices.size(), 6U);
+  return vertices;
+}
+
+void ResolutionSet::TryAddVertex(std::vector<Point>* vertices,
+                                 const Point& point) const {
+  if (!ContainsPoint(point))
+    return;
+
+  // Add the point to the |vertices| if not already added.
+  // This is to prevent duplicates in case an aspect ratio intersects a width
+  // or height right on a vertex.
+  if (vertices->empty() ||
+      (*(vertices->end() - 1) != point && *vertices->begin() != point)) {
+    vertices->push_back(point);
+  }
+}
+
+ResolutionSet ResolutionSet::FromConstraintSet(
+    const blink::WebMediaTrackConstraintSet& constraint_set) {
+  return ResolutionSet(
+      MinDimensionFromConstraint(constraint_set.height),
+      MaxDimensionFromConstraint(constraint_set.height),
+      MinDimensionFromConstraint(constraint_set.width),
+      MaxDimensionFromConstraint(constraint_set.width),
+      MinAspectRatioFromConstraint(constraint_set.aspectRatio),
+      MaxAspectRatioFromConstraint(constraint_set.aspectRatio));
+}
+
+}  // namespace content