1 files changed, 149 insertions, 0 deletions
diff --git a/layout/base/ShapeUtils.cpp b/layout/base/ShapeUtils.cpp
new file mode 100644
index 0000000000..4cdc7b2353
--- /dev/null
+++ b/layout/base/ShapeUtils.cpp
@@ -0,0 +1,149 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ShapeUtils.h"
+
+#include <cstdlib>
+
+#include "nsCSSRendering.h"
+#include "nsMargin.h"
+#include "nsStyleStruct.h"
+#include "mozilla/SVGContentUtils.h"
+
+namespace mozilla {
+
+nscoord ShapeUtils::ComputeShapeRadius(const StyleShapeRadius& aType,
+                                       const nscoord aCenter,
+                                       const nscoord aPosMin,
+                                       const nscoord aPosMax) {
+  MOZ_ASSERT(aType.IsFarthestSide() || aType.IsClosestSide());
+  nscoord dist1 = std::abs(aPosMin - aCenter);
+  nscoord dist2 = std::abs(aPosMax - aCenter);
+  nscoord length = 0;
+  if (aType.IsFarthestSide()) {
+    length = dist1 > dist2 ? dist1 : dist2;
+  } else {
+    length = dist1 > dist2 ? dist2 : dist1;
+  }
+  return length;
+}
+
+nsPoint ShapeUtils::ComputeCircleOrEllipseCenter(
+    const StyleBasicShape& aBasicShape, const nsRect& aRefBox) {
+  MOZ_ASSERT(aBasicShape.IsCircle() || aBasicShape.IsEllipse(),
+             "The basic shape must be circle() or ellipse!");
+
+  const auto& position = aBasicShape.IsCircle()
+                             ? aBasicShape.AsCircle().position
+                             : aBasicShape.AsEllipse().position;
+
+  nsPoint topLeft, anchor;
+  nsSize size(aRefBox.Size());
+  nsImageRenderer::ComputeObjectAnchorPoint(position, size, size, &topLeft,
+                                            &anchor);
+  return anchor + aRefBox.TopLeft();
+}
+
+nscoord ShapeUtils::ComputeCircleRadius(const StyleBasicShape& aBasicShape,
+                                        const nsPoint& aCenter,
+                                        const nsRect& aRefBox) {
+  MOZ_ASSERT(aBasicShape.IsCircle(), "The basic shape must be circle()!");
+  const auto& radius = aBasicShape.AsCircle().radius;
+  if (radius.IsLength()) {
+    return radius.AsLength().Resolve([&] {
+      // We resolve percent <shape-radius> value for circle() as defined here:
+      // https://drafts.csswg.org/css-shapes/#funcdef-circle
+      double referenceLength = SVGContentUtils::ComputeNormalizedHypotenuse(
+          aRefBox.width, aRefBox.height);
+      return NSToCoordRound(referenceLength);
+    });
+  }
+
+  nscoord horizontal =
+      ComputeShapeRadius(radius, aCenter.x, aRefBox.x, aRefBox.XMost());
+  nscoord vertical =
+      ComputeShapeRadius(radius, aCenter.y, aRefBox.y, aRefBox.YMost());
+  return radius.IsFarthestSide() ? std::max(horizontal, vertical)
+                                 : std::min(horizontal, vertical);
+}
+
+nsSize ShapeUtils::ComputeEllipseRadii(const StyleBasicShape& aBasicShape,
+                                       const nsPoint& aCenter,
+                                       const nsRect& aRefBox) {
+  MOZ_ASSERT(aBasicShape.IsEllipse(), "The basic shape must be ellipse()!");
+  const auto& ellipse = aBasicShape.AsEllipse();
+  nsSize radii;
+  if (ellipse.semiaxis_x.IsLength()) {
+    radii.width = ellipse.semiaxis_x.AsLength().Resolve(aRefBox.width);
+  } else {
+    radii.width = ComputeShapeRadius(ellipse.semiaxis_x, aCenter.x, aRefBox.x,
+                                     aRefBox.XMost());
+  }
+
+  if (ellipse.semiaxis_y.IsLength()) {
+    radii.height = ellipse.semiaxis_y.AsLength().Resolve(aRefBox.height);
+  } else {
+    radii.height = ComputeShapeRadius(ellipse.semiaxis_y, aCenter.y, aRefBox.y,
+                                      aRefBox.YMost());
+  }
+
+  return radii;
+}
+
+/* static */
+nsRect ShapeUtils::ComputeInsetRect(const StyleBasicShape& aBasicShape,
+                                    const nsRect& aRefBox) {
+  MOZ_ASSERT(aBasicShape.IsInset(), "The basic shape must be inset()!");
+  const auto& rect = aBasicShape.AsInset().rect;
+  nsMargin inset(
+      rect._0.Resolve(aRefBox.Height()), rect._1.Resolve(aRefBox.Width()),
+      rect._2.Resolve(aRefBox.Height()), rect._3.Resolve(aRefBox.Width()));
+
+  nscoord x = aRefBox.X() + inset.left;
+  nscoord width = aRefBox.Width() - inset.LeftRight();
+  nscoord y = aRefBox.Y() + inset.top;
+  nscoord height = aRefBox.Height() - inset.TopBottom();
+
+  // Invert left and right, if necessary.
+  if (width < 0) {
+    width *= -1;
+    x -= width;
+  }
+
+  // Invert top and bottom, if necessary.
+  if (height < 0) {
+    height *= -1;
+    y -= height;
+  }
+
+  return nsRect(x, y, width, height);
+}
+
+/* static */
+bool ShapeUtils::ComputeInsetRadii(const StyleBasicShape& aBasicShape,
+                                   const nsRect& aInsetRect,
+                                   const nsRect& aRefBox, nscoord aRadii[8]) {
+  const auto& radius = aBasicShape.AsInset().round;
+  return nsIFrame::ComputeBorderRadii(radius, aInsetRect.Size(), aRefBox.Size(),
+                                      Sides(), aRadii);
+}
+
+/* static */
+nsTArray<nsPoint> ShapeUtils::ComputePolygonVertices(
+    const StyleBasicShape& aBasicShape, const nsRect& aRefBox) {
+  MOZ_ASSERT(aBasicShape.IsPolygon(), "The basic shape must be polygon()!");
+
+  auto coords = aBasicShape.AsPolygon().coordinates.AsSpan();
+  nsTArray<nsPoint> vertices(coords.Length());
+  for (const StylePolygonCoord<LengthPercentage>& point : coords) {
+    vertices.AppendElement(nsPoint(point._0.Resolve(aRefBox.width),
+                                   point._1.Resolve(aRefBox.height)) +
+                           aRefBox.TopLeft());
+  }
+  return vertices;
+}
+
+}  // namespace mozilla