gecko-dev/gfx/2d/Tools.h

214 lines
5.4 KiB
C++

/* -*- 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/TypeTraits.h"
#include "Types.h"
#include "Point.h"
#include <math.h>
#if defined(_MSC_VER) && (_MSC_VER < 1600)
#define hypotf _hypotf
#endif
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:
return 2;
default:
return 4;
}
}
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
moz_free(mStorage);
mStorage = nullptr;
mPtr = nullptr;
}
MOZ_ALWAYS_INLINE void Realloc(size_t aCount, bool aZero = false)
{
moz_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 *>(moz_calloc(1, storageByteCount.value()));
} else {
mStorage = static_cast<uint8_t *>(moz_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;
}
MOZ_ALWAYS_INLINE operator T*()
{
return mPtr;
}
T *mPtr;
private:
uint8_t *mStorage;
size_t mCount;
};
/**
* Returns aStride 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 aStride)
{
static_assert(alignment > 0 && (alignment & (alignment-1)) == 0,
"This implementation currently require power-of-two alignment");
const int32_t mask = alignment - 1;
return (aStride + mask) & ~mask;
}
}
}
#endif /* MOZILLA_GFX_TOOLS_H_ */