1 files changed, 62 insertions, 0 deletions
diff --git a/gfx/layers/DirectionUtils.h b/gfx/layers/DirectionUtils.h
new file mode 100644
index 0000000000..84d9cb6969
--- /dev/null
+++ b/gfx/layers/DirectionUtils.h
@@ -0,0 +1,62 @@
+/* -*- 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 GFX_DIRECTIONUTILS_H
+#define GFX_DIRECTIONUTILS_H
+
+#include "LayersTypes.h"  // for ScrollDirection
+#include "Units.h"        // for Coord, Point, and Rect types
+
+namespace mozilla {
+namespace layers {
+
+template <typename PointOrRect>
+CoordOf<PointOrRect> GetAxisStart(ScrollDirection aDir,
+                                  const PointOrRect& aValue) {
+  if (aDir == ScrollDirection::eHorizontal) {
+    return aValue.X();
+  } else {
+    return aValue.Y();
+  }
+}
+
+template <typename Rect>
+CoordOf<Rect> GetAxisEnd(ScrollDirection aDir, const Rect& aValue) {
+  if (aDir == ScrollDirection::eHorizontal) {
+    return aValue.XMost();
+  } else {
+    return aValue.YMost();
+  }
+}
+
+template <typename Rect>
+CoordOf<Rect> GetAxisLength(ScrollDirection aDir, const Rect& aValue) {
+  if (aDir == ScrollDirection::eHorizontal) {
+    return aValue.Width();
+  } else {
+    return aValue.Height();
+  }
+}
+
+template <typename FromUnits, typename ToUnits>
+float GetAxisScale(ScrollDirection aDir,
+                   const gfx::ScaleFactors2D<FromUnits, ToUnits>& aValue) {
+  if (aDir == ScrollDirection::eHorizontal) {
+    return aValue.xScale;
+  } else {
+    return aValue.yScale;
+  }
+}
+
+inline ScrollDirection GetPerpendicularDirection(ScrollDirection aDir) {
+  return aDir == ScrollDirection::eHorizontal ? ScrollDirection::eVertical
+                                              : ScrollDirection::eHorizontal;
+}
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif /* GFX_DIRECTIONUTILS_H */