Bug 1311244 Part 2 - Create ShapeUtils, and move EnumerationToLength into it. r=dbaron

More functions in nsCSSClipPathInstance will be refactored and moved into
ShapeUtils in subsequent patches.

MozReview-Commit-ID: LmJUevY8YGr

--HG--
extra : rebase_source : 8888fa26fab541d06a3fccad9e4376bb3a66c043

layout/base/ShapeUtils.cpp

@@ -0,0 +1,33 @@
+/* -*- 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>
+
+namespace mozilla {
+
+nscoord
+ShapeUtils::ComputeShapeRadius(const StyleShapeRadius aType,
+                               const nscoord aCenter,
+                               const nscoord aPosMin,
+                               const nscoord aPosMax)
+{
+  nscoord dist1 = std::abs(aPosMin - aCenter);
+  nscoord dist2 = std::abs(aPosMax - aCenter);
+  nscoord length = 0;
+  switch (aType) {
+    case StyleShapeRadius::FarthestSide:
+      length = dist1 > dist2 ? dist1 : dist2;
+      break;
+    case StyleShapeRadius::ClosestSide:
+      length = dist1 > dist2 ? dist2 : dist1;
+      break;
+  }
+  return length;
+}
+
+} // namespace mozilla

layout/base/ShapeUtils.h

@@ -0,0 +1,35 @@
+/* -*- 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/. */
+
+#ifndef mozilla_ShapeUtils_h
+#define mozilla_ShapeUtils_h
+
+#include "nsCoord.h"
+#include "nsStyleConsts.h"
+
+namespace mozilla {
+
+// ShapeUtils is a namespace class containing utility functions related to
+// processing basic shapes in the CSS Shapes Module.
+// https://drafts.csswg.org/css-shapes/#basic-shape-functions
+//
+struct ShapeUtils final
+{
+  // Compute the length of a keyword <shape-radius>, i.e. closest-side or
+  // farthest-side, for a circle or an ellipse on a single dimension. The
+  // caller needs to call for both dimensions and combine the result.
+  // https://drafts.csswg.org/css-shapes/#typedef-shape-radius.
+  //
+  // @return The length of the radius in app units.
+  static nscoord ComputeShapeRadius(const StyleShapeRadius aType,
+                                    const nscoord aCenter,
+                                    const nscoord aPosMin,
+                                    const nscoord aPosMax);
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ShapeUtils_h

layout/base/moz.build

@@ -80,6 +80,7 @@ EXPORTS.mozilla += [
     'RestyleManagerHandleInlines.h',
     'ServoRestyleManager.h',
     'ServoRestyleManagerInlines.h',
+    'ShapeUtils.h',
     'StaticPresData.h',
 ]
 
@@ -114,6 +115,7 @@ UNIFIED_SOURCES += [
     'RestyleTracker.cpp',
     'ScrollbarStyles.cpp',
     'ServoRestyleManager.cpp',
+    'ShapeUtils.cpp',
     'StackArena.cpp',
     'StaticPresData.cpp',
     'TouchManager.cpp',

layout/svg/nsCSSClipPathInstance.cpp

@@ -11,6 +11,7 @@
 #include "mozilla/dom/SVGSVGElement.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/gfx/PathHelpers.h"
+#include "mozilla/ShapeUtils.h"
 #include "nsCSSRendering.h"
 #include "nsIFrame.h"
 #include "nsRenderingContext.h"
@@ -104,22 +105,6 @@ nsCSSClipPathInstance::CreateClipPath(DrawTarget* aDrawTarget)
   return builder->Finish();
 }
 
-static void
-EnumerationToLength(nscoord& aCoord, StyleShapeRadius aType,
-                    nscoord aCenter, nscoord aPosMin, nscoord aPosMax)
-{
-  nscoord dist1 = abs(aPosMin - aCenter);
-  nscoord dist2 = abs(aPosMax - aCenter);
-  switch (aType) {
-    case StyleShapeRadius::FarthestSide:
-      aCoord = dist1 > dist2 ? dist1 : dist2;
-      break;
-    case StyleShapeRadius::ClosestSide:
-      aCoord = dist1 > dist2 ? dist2 : dist1;
-      break;
-  }
-}
-
 already_AddRefed<Path>
 nsCSSClipPathInstance::CreateClipPathCircle(DrawTarget* aDrawTarget,
                                             const nsRect& aRefBox)
@@ -140,11 +125,12 @@ nsCSSClipPathInstance::CreateClipPathCircle(DrawTarget* aDrawTarget,
   nscoord r = 0;
   if (coords[0].GetUnit() == eStyleUnit_Enumerated) {
     const auto styleShapeRadius = coords[0].GetEnumValue<StyleShapeRadius>();
-    nscoord horizontal, vertical;
-    EnumerationToLength(horizontal, styleShapeRadius,
-                        center.x, aRefBox.x, aRefBox.x + aRefBox.width);
-    EnumerationToLength(vertical, styleShapeRadius,
-                        center.y, aRefBox.y, aRefBox.y + aRefBox.height);
+    nscoord horizontal =
+      ShapeUtils::ComputeShapeRadius(styleShapeRadius, center.x, aRefBox.x,
+                                     aRefBox.x + aRefBox.width);
+    nscoord vertical =
+      ShapeUtils::ComputeShapeRadius(styleShapeRadius, center.y, aRefBox.y,
+                                     aRefBox.y + aRefBox.height);
     if (styleShapeRadius == StyleShapeRadius::FarthestSide) {
       r = horizontal > vertical ? horizontal : vertical;
     } else {
@@ -188,14 +174,18 @@ nsCSSClipPathInstance::CreateClipPathEllipse(DrawTarget* aDrawTarget,
   MOZ_ASSERT(coords.Length() == 2, "wrong number of arguments");
   nscoord rx = 0, ry = 0;
   if (coords[0].GetUnit() == eStyleUnit_Enumerated) {
-    EnumerationToLength(rx, coords[0].GetEnumValue<StyleShapeRadius>(),
-                        center.x, aRefBox.x, aRefBox.x + aRefBox.width);
+    rx = ShapeUtils::ComputeShapeRadius(coords[0].GetEnumValue<StyleShapeRadius>(),
+                                        center.x,
+                                        aRefBox.x,
+                                        aRefBox.x + aRefBox.width);
   } else {
     rx = nsRuleNode::ComputeCoordPercentCalc(coords[0], aRefBox.width);
   }
   if (coords[1].GetUnit() == eStyleUnit_Enumerated) {
-    EnumerationToLength(ry, coords[1].GetEnumValue<StyleShapeRadius>(),
-                        center.y, aRefBox.y, aRefBox.y + aRefBox.height);
+    ry = ShapeUtils::ComputeShapeRadius(coords[1].GetEnumValue<StyleShapeRadius>(),
+                                        center.y,
+                                        aRefBox.y,
+                                        aRefBox.y + aRefBox.height);
   } else {
     ry = nsRuleNode::ComputeCoordPercentCalc(coords[1], aRefBox.height);
   }