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

88 lines
1.8 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 "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 OP_IN:
case OP_OUT:
case OP_DEST_IN:
case OP_DEST_ATOP:
case 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 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 FORMAT_A8:
return 1;
case FORMAT_R5G6B5:
return 2;
default:
return 4;
}
}
}
}
#endif /* MOZILLA_GFX_TOOLS_H_ */