1 files changed, 246 insertions, 0 deletions
diff --git a/gfx/2d/Tools.h b/gfx/2d/Tools.h
new file mode 100644
index 000000000..585cbbb2c
--- /dev/null
+++ b/gfx/2d/Tools.h
@@ -0,0 +1,246 @@
+/* -*- 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_TOOLS_H_
+#define MOZILLA_GFX_TOOLS_H_
+
+#include "mozilla/CheckedInt.h"
+#include "mozilla/Move.h"
+#include "mozilla/TypeTraits.h"
+#include "Types.h"
+#include "Point.h"
+#include <math.h>
+
+namespace mozilla {
+namespace gfx {
+
+static inline bool
+IsOperatorBoundByMask(CompositionOp aOp) {
+  switch (aOp) {
+  case CompositionOp::OP_IN:
+  case CompositionOp::OP_OUT:
+  case CompositionOp::OP_DEST_IN:
+  case CompositionOp::OP_DEST_ATOP:
+  case CompositionOp::OP_SOURCE:
+    return false;
+  default:
+    return true;
+  }
+}
+
+template <class T>
+struct ClassStorage
+{
+  char bytes[sizeof(T)];
+
+  const T *addr() const { return (const T *)bytes; }
+  T *addr() { return (T *)(void *)bytes; }
+};
+
+static inline bool
+FuzzyEqual(Float aA, Float aB, Float aErr)
+{
+  if ((aA + aErr >= aB) && (aA - aErr <= aB)) {
+    return true;
+  }
+  return false;
+}
+
+static inline void
+NudgeToInteger(float *aVal)
+{
+  float r = floorf(*aVal + 0.5f);
+  // The error threshold should be proportional to the rounded value. This
+  // bounds the relative error introduced by the nudge operation. However,
+  // when the rounded value is 0, the error threshold can't be proportional
+  // to the rounded value (we'd never round), so we just choose the same
+  // threshold as for a rounded value of 1.
+  if (FuzzyEqual(r, *aVal, r == 0.0f ? 1e-6f : fabs(r*1e-6f))) {
+    *aVal = r;
+  }
+}
+
+static inline void
+NudgeToInteger(float *aVal, float aErr)
+{
+  float r = floorf(*aVal + 0.5f);
+  if (FuzzyEqual(r, *aVal, aErr)) {
+    *aVal = r;
+  }
+}
+
+static inline Float
+Distance(Point aA, Point aB)
+{
+  return hypotf(aB.x - aA.x, aB.y - aA.y);
+}
+
+static inline int
+BytesPerPixel(SurfaceFormat aFormat)
+{
+  switch (aFormat) {
+  case SurfaceFormat::A8:
+    return 1;
+  case SurfaceFormat::R5G6B5_UINT16:
+    return 2;
+  case SurfaceFormat::R8G8B8:
+  case SurfaceFormat::B8G8R8:
+    return 3;
+  case SurfaceFormat::HSV:
+  case SurfaceFormat::Lab:
+    return 3 * sizeof(float);
+  case SurfaceFormat::Depth:
+    return sizeof(uint16_t);
+  default:
+    return 4;
+  }
+}
+
+static inline bool
+IsOpaqueFormat(SurfaceFormat aFormat) {
+  switch (aFormat) {
+    case SurfaceFormat::B8G8R8X8:
+    case SurfaceFormat::R8G8B8X8:
+    case SurfaceFormat::X8R8G8B8:
+    case SurfaceFormat::YUV:
+    case SurfaceFormat::NV12:
+    case SurfaceFormat::YUV422:
+    case SurfaceFormat::R5G6B5_UINT16:
+      return true;
+    default:
+      return false;
+  }
+}
+
+template<typename T, int alignment = 16>
+struct AlignedArray
+{
+  typedef T value_type;
+
+  AlignedArray()
+    : mPtr(nullptr)
+    , mStorage(nullptr)
+  {
+  }
+
+  explicit MOZ_ALWAYS_INLINE AlignedArray(size_t aCount, bool aZero = false)
+    : mStorage(nullptr)
+    , mCount(0)
+  {
+    Realloc(aCount, aZero);
+  }
+
+  MOZ_ALWAYS_INLINE ~AlignedArray()
+  {
+    Dealloc();
+  }
+
+  void Dealloc()
+  {
+    // If we fail this assert we'll need to uncomment the loop below to make
+    // sure dtors are properly invoked. If we do that, we should check that the
+    // comment about compiler dead code elimination is in fact true for all the
+    // compilers that we care about.
+    static_assert(mozilla::IsPod<T>::value,
+                  "Destructors must be invoked for this type");
+#if 0
+    for (size_t i = 0; i < mCount; ++i) {
+      // Since we used the placement |operator new| function to construct the
+      // elements of this array we need to invoke their destructors manually.
+      // For types where the destructor does nothing the compiler's dead code
+      // elimination step should optimize this loop away.
+      mPtr[i].~T();
+    }
+#endif
+
+    free(mStorage);
+    mStorage = nullptr;
+    mPtr = nullptr;
+  }
+
+  MOZ_ALWAYS_INLINE void Realloc(size_t aCount, bool aZero = false)
+  {
+    free(mStorage);
+    CheckedInt32 storageByteCount =
+      CheckedInt32(sizeof(T)) * aCount + (alignment - 1);
+    if (!storageByteCount.isValid()) {
+      mStorage = nullptr;
+      mPtr = nullptr;
+      mCount = 0;
+      return;
+    }
+    // We don't create an array of T here, since we don't want ctors to be
+    // invoked at the wrong places if we realign below.
+    if (aZero) {
+      // calloc can be more efficient than new[] for large chunks,
+      // so we use calloc/malloc/free for everything.
+      mStorage = static_cast<uint8_t *>(calloc(1, storageByteCount.value()));
+    } else {
+      mStorage = static_cast<uint8_t *>(malloc(storageByteCount.value()));
+    }
+    if (!mStorage) {
+      mStorage = nullptr;
+      mPtr = nullptr;
+      mCount = 0;
+      return;
+    }
+    if (uintptr_t(mStorage) % alignment) {
+      // Our storage does not start at a <alignment>-byte boundary. Make sure mPtr does!
+      mPtr = (T*)(uintptr_t(mStorage) + alignment - (uintptr_t(mStorage) % alignment));
+    } else {
+      mPtr = (T*)(mStorage);
+    }
+    // Now that mPtr is pointing to the aligned position we can use placement
+    // |operator new| to invoke any ctors at the correct positions. For types
+    // that have a no-op default constructor the compiler's dead code
+    // elimination step should optimize this away.
+    mPtr = new (mPtr) T[aCount];
+    mCount = aCount;
+  }
+
+  void Swap(AlignedArray<T, alignment>& aOther)
+  {
+    mozilla::Swap(mPtr, aOther.mPtr);
+    mozilla::Swap(mStorage, aOther.mStorage);
+    mozilla::Swap(mCount, aOther.mCount);
+  }
+
+  MOZ_ALWAYS_INLINE operator T*()
+  {
+    return mPtr;
+  }
+
+  T *mPtr;
+
+private:
+  uint8_t *mStorage;
+  size_t mCount;
+};
+
+/**
+ * Returns aWidth * aBytesPerPixel increased, if necessary, so that it divides
+ * exactly into |alignment|.
+ *
+ * Note that currently |alignment| must be a power-of-2. If for some reason we
+ * want to support NPOT alignment we can revert back to this functions old
+ * implementation.
+ */
+template<int alignment>
+int32_t GetAlignedStride(int32_t aWidth, int32_t aBytesPerPixel)
+{
+  static_assert(alignment > 0 && (alignment & (alignment-1)) == 0,
+                "This implementation currently require power-of-two alignment");
+  const int32_t mask = alignment - 1;
+  CheckedInt32 stride = CheckedInt32(aWidth) * CheckedInt32(aBytesPerPixel) + CheckedInt32(mask);
+  if (stride.isValid()) {
+    return stride.value() & ~mask;
+  }
+  return 0;
+}
+
+} // namespace gfx
+} // namespace mozilla
+
+#endif /* MOZILLA_GFX_TOOLS_H_ */