layout/base/ShapeUtils.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/ShapeUtils.h"
   8
   9 #include <cstdlib>
  10
  11 #include "nsCSSRendering.h"
  12 #include "nsMargin.h"
  13 #include "nsStyleStruct.h"
  14 #include "mozilla/SVGContentUtils.h"
  15
  16 namespace mozilla {
  17
  18 nscoord ShapeUtils::ComputeShapeRadius(const StyleShapeRadius& aType,
  19                                        const nscoord aCenter,
  20                                        const nscoord aPosMin,
  21                                        const nscoord aPosMax) {
  22   MOZ_ASSERT(aType.IsFarthestSide() || aType.IsClosestSide());
  23   nscoord dist1 = std::abs(aPosMin - aCenter);
  24   nscoord dist2 = std::abs(aPosMax - aCenter);
  25   nscoord length = 0;
  26   if (aType.IsFarthestSide()) {
  27     length = dist1 > dist2 ? dist1 : dist2;
  28   } else {
  29     length = dist1 > dist2 ? dist2 : dist1;
  30   }
  31   return length;
  32 }
  33
  34 nsPoint ShapeUtils::ComputeCircleOrEllipseCenter(
  35     const StyleBasicShape& aBasicShape, const nsRect& aRefBox) {
  36   MOZ_ASSERT(aBasicShape.IsCircle() || aBasicShape.IsEllipse(),
  37              "The basic shape must be circle() or ellipse!");
  38
  39   const auto& position = aBasicShape.IsCircle()
  40                              ? aBasicShape.AsCircle().position
  41                              : aBasicShape.AsEllipse().position;
  42
  43   nsPoint topLeft, anchor;
  44   nsSize size(aRefBox.Size());
  45   nsImageRenderer::ComputeObjectAnchorPoint(position, size, size, &topLeft,
  46                                             &anchor);
  47   return anchor + aRefBox.TopLeft();
  48 }
  49
  50 nscoord ShapeUtils::ComputeCircleRadius(const StyleBasicShape& aBasicShape,
  51                                         const nsPoint& aCenter,
  52                                         const nsRect& aRefBox) {
  53   MOZ_ASSERT(aBasicShape.IsCircle(), "The basic shape must be circle()!");
  54   const auto& radius = aBasicShape.AsCircle().radius;
  55   if (radius.IsLength()) {
  56     return radius.AsLength().Resolve([&] {
  57       // We resolve percent <shape-radius> value for circle() as defined here:
  58       // https://drafts.csswg.org/css-shapes/#funcdef-circle
  59       double referenceLength = SVGContentUtils::ComputeNormalizedHypotenuse(
  60           aRefBox.width, aRefBox.height);
  61       return NSToCoordRound(referenceLength);
  62     });
  63   }
  64
  65   nscoord horizontal =
  66       ComputeShapeRadius(radius, aCenter.x, aRefBox.x, aRefBox.XMost());
  67   nscoord vertical =
  68       ComputeShapeRadius(radius, aCenter.y, aRefBox.y, aRefBox.YMost());
  69   return radius.IsFarthestSide() ? std::max(horizontal, vertical)
  70                                  : std::min(horizontal, vertical);
  71 }
  72
  73 nsSize ShapeUtils::ComputeEllipseRadii(const StyleBasicShape& aBasicShape,
  74                                        const nsPoint& aCenter,
  75                                        const nsRect& aRefBox) {
  76   MOZ_ASSERT(aBasicShape.IsEllipse(), "The basic shape must be ellipse()!");
  77   const auto& ellipse = aBasicShape.AsEllipse();
  78   nsSize radii;
  79   if (ellipse.semiaxis_x.IsLength()) {
  80     radii.width = ellipse.semiaxis_x.AsLength().Resolve(aRefBox.width);
  81   } else {
  82     radii.width = ComputeShapeRadius(ellipse.semiaxis_x, aCenter.x, aRefBox.x,
  83                                      aRefBox.XMost());
  84   }
  85
  86   if (ellipse.semiaxis_y.IsLength()) {
  87     radii.height = ellipse.semiaxis_y.AsLength().Resolve(aRefBox.height);
  88   } else {
  89     radii.height = ComputeShapeRadius(ellipse.semiaxis_y, aCenter.y, aRefBox.y,
  90                                       aRefBox.YMost());
  91   }
  92
  93   return radii;
  94 }
  95
  96 /* static */
  97 nsRect ShapeUtils::ComputeInsetRect(const StyleBasicShape& aBasicShape,
  98                                     const nsRect& aRefBox) {
  99   MOZ_ASSERT(aBasicShape.IsInset(), "The basic shape must be inset()!");
 100   const auto& rect = aBasicShape.AsInset().rect;
 101   nsMargin inset(
 102       rect._0.Resolve(aRefBox.Height()), rect._1.Resolve(aRefBox.Width()),
 103       rect._2.Resolve(aRefBox.Height()), rect._3.Resolve(aRefBox.Width()));
 104
 105   nscoord x = aRefBox.X() + inset.left;
 106   nscoord width = aRefBox.Width() - inset.LeftRight();
 107   nscoord y = aRefBox.Y() + inset.top;
 108   nscoord height = aRefBox.Height() - inset.TopBottom();
 109
 110   // Invert left and right, if necessary.
 111   if (width < 0) {
 112     width *= -1;
 113     x -= width;
 114   }
 115
 116   // Invert top and bottom, if necessary.
 117   if (height < 0) {
 118     height *= -1;
 119     y -= height;
 120   }
 121
 122   return nsRect(x, y, width, height);
 123 }
 124
 125 /* static */
 126 bool ShapeUtils::ComputeInsetRadii(const StyleBasicShape& aBasicShape,
 127                                    const nsRect& aRefBox,
 128                                    const nsRect& aInsetRect,
 129                                    nscoord aRadii[8]) {
 130   const auto& radius = aBasicShape.AsInset().round;
 131   return nsIFrame::ComputeBorderRadii(radius, aRefBox.Size(), aInsetRect.Size(),
 132                                       Sides(), aRadii);
 133 }
 134
 135 /* static */
 136 nsTArray<nsPoint> ShapeUtils::ComputePolygonVertices(
 137     const StyleBasicShape& aBasicShape, const nsRect& aRefBox) {
 138   MOZ_ASSERT(aBasicShape.IsPolygon(), "The basic shape must be polygon()!");
 139
 140   auto coords = aBasicShape.AsPolygon().coordinates.AsSpan();
 141   nsTArray<nsPoint> vertices(coords.Length());
 142   for (const StylePolygonCoord<LengthPercentage>& point : coords) {
 143     vertices.AppendElement(nsPoint(point._0.Resolve(aRefBox.width),
 144                                    point._1.Resolve(aRefBox.height)) +
 145                            aRefBox.TopLeft());
 146   }
 147   return vertices;
 148 }
 149
 150 }  // namespace mozilla