Bug 1259248. Add an ArrayView class. r=botond

gfx/src/ArrayView.h

@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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_GFX_ARRAY_VIEW_H_
+#define MOZILLA_GFX_ARRAY_VIEW_H_
+
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace gfx {
+
+template<typename T>
+class ArrayView
+{
+    public:
+        ArrayView(const nsTArray<T>& aData) :
+            mData(aData.Elements()), mLength(aData.Length())
+        {
+        }
+        ArrayView(const T* aData, const size_t aLength) :
+            mData(aData), mLength(aLength)
+        {
+        }
+        const T& operator[](const size_t aIdx) const
+        {
+            return mData[aIdx];
+        }
+        size_t Length() const
+        {
+            return mLength;
+        }
+        const T* Data() const
+        {
+            return mData;
+        }
+    private:
+        const T* mData;
+        const size_t mLength;
+};
+
+} // namespace gfx
+} // namespace mozilla
+
+#endif /* MOZILLA_GFX_ARRAY_VIEW_H_ */

gfx/src/moz.build

@@ -43,6 +43,7 @@ EXPORTS += [
 
 EXPORTS.mozilla += [
     'AppUnits.h',
+    'ArrayView.h',
 ]
 
 if CONFIG['MOZ_X11']:

gfx/src/nsRegion.h

@@ -19,8 +19,8 @@
 #include "nsMargin.h"                   // for nsIntMargin
 #include "nsRegionFwd.h"                // for nsIntRegion
 #include "nsStringGlue.h"               // for nsCString
-#include "nsTArray.h"                   // for nsTArray, nsTArray_Impl
 #include "xpcom-config.h"               // for CPP_THROW_NEW
+#include "mozilla/ArrayView.h"          // for ArrayView
 #include "mozilla/Move.h"               // for mozilla::Move
 #include "mozilla/gfx/MatrixFwd.h"      // for mozilla::gfx::Matrix4x4
 
@@ -60,9 +60,9 @@ public:
                                                                           aRect.y,
                                                                           aRect.width,
                                                                           aRect.height); }
-  explicit nsRegion (const nsTArray<pixman_box32_t>& aRects)
+  explicit nsRegion (mozilla::gfx::ArrayView<pixman_box32_t> aRects)
   {
-    pixman_region32_init_rects(&mImpl, aRects.Elements(), aRects.Length());
+    pixman_region32_init_rects(&mImpl, aRects.Data(), aRects.Length());
   }
   nsRegion (const nsRegion& aRegion) { pixman_region32_init(&mImpl); pixman_region32_copy(&mImpl,aRegion.Impl()); }
   nsRegion (nsRegion&& aRegion) { mImpl = aRegion.mImpl; pixman_region32_init(&aRegion.mImpl); }
@@ -480,7 +480,7 @@ public:
 
   BaseIntRegion () {}
   MOZ_IMPLICIT BaseIntRegion (const Rect& aRect) : mImpl (ToRect(aRect)) {}
-  explicit BaseIntRegion (const nsTArray<pixman_box32_t>& aRects) : mImpl (aRects) {}
+  explicit BaseIntRegion (mozilla::gfx::ArrayView<pixman_box32_t> aRects) : mImpl (aRects) {}
   BaseIntRegion (const BaseIntRegion& aRegion) : mImpl (aRegion.mImpl) {}
   BaseIntRegion (BaseIntRegion&& aRegion) : mImpl (mozilla::Move(aRegion.mImpl)) {}
   Derived& operator = (const Rect& aRect) { mImpl = ToRect (aRect); return This(); }
@@ -832,7 +832,7 @@ public:
   IntRegionTyped() {}
   MOZ_IMPLICIT IntRegionTyped(const IntRectTyped<units>& aRect) : Super(aRect) {}
   IntRegionTyped(const IntRegionTyped& aRegion) : Super(aRegion) {}
-  explicit IntRegionTyped(const nsTArray<pixman_box32_t>& aRects) : Super(aRects) {}
+  explicit IntRegionTyped(mozilla::gfx::ArrayView<pixman_box32_t> aRects) : Super(aRects) {}
   IntRegionTyped(IntRegionTyped&& aRegion) : Super(mozilla::Move(aRegion)) {}
 
   // Assignment operators need to be forwarded as well, otherwise the compiler

gfx/tests/gtest/TestArrayView.cpp

@@ -0,0 +1,18 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 <limits>
+
+#include "gtest/gtest.h"
+
+#include "mozilla/ArrayView.h"
+
+using namespace mozilla::gfx;
+
+TEST(Gfx, ArrayView) {
+    nsTArray<int> p = {5, 6};
+    ArrayView<int> pv(p);
+    ASSERT_EQ(pv[1], 6);
+    ASSERT_EQ(*pv.Data(), 5);
+}

gfx/tests/gtest/moz.build

@@ -9,6 +9,7 @@ UNIFIED_SOURCES += [
     # Disabled on suspicion of causing bug 904227
     #'gfxWordCacheTest.cpp',
     'TestArena.cpp',
+    'TestArrayView.cpp',
     'TestBufferRotation.cpp',
     'TestColorNames.cpp',
     'TestCompositor.cpp',