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/* -*- 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
#include "ImageScaling.h"
#include "2D.h"
#include "DataSurfaceHelpers.h"
#include <math.h>
#include <algorithm>
namespace mozilla {
namespace gfx {
inline uint32_t Avg2x2(uint32_t a, uint32_t b, uint32_t c, uint32_t d) {
// Prepare half-adder work
uint32_t sum = a ^ b ^ c;
uint32_t carry = (a & b) | (a & c) | (b & c);
// Before shifting, mask lower order bits of each byte to avoid underflow.
uint32_t mask = 0xfefefefe;
// Add d to sum and divide by 2.
sum = (((sum ^ d) & mask) >> 1) + (sum & d);
// Sum is now shifted into place relative to carry, add them together.
return (((sum ^ carry) & mask) >> 1) + (sum & carry);
}
inline uint32_t Avg2(uint32_t a, uint32_t b) {
// Prepare half-adder work
uint32_t sum = a ^ b;
uint32_t carry = (a & b);
// Before shifting, mask lower order bits of each byte to avoid underflow.
uint32_t mask = 0xfefefefe;
// Add d to sum and divide by 2.
return ((sum & mask) >> 1) + carry;
}
void ImageHalfScaler::ScaleForSize(const IntSize& aSize) {
uint32_t horizontalDownscales = 0;
uint32_t verticalDownscales = 0;
IntSize scaleSize = mOrigSize;
while ((scaleSize.height / 2) > aSize.height) {
verticalDownscales++;
scaleSize.height /= 2;
}
while ((scaleSize.width / 2) > aSize.width) {
horizontalDownscales++;
scaleSize.width /= 2;
}
if (scaleSize == mOrigSize) {
return;
}
delete[] mDataStorage;
IntSize internalSurfSize;
internalSurfSize.width = std::max(scaleSize.width, mOrigSize.width / 2);
internalSurfSize.height = std::max(scaleSize.height, mOrigSize.height / 2);
size_t bufLen = 0;
mStride = GetAlignedStride<16>(internalSurfSize.width, 4);
if (mStride > 0) {
// Allocate 15 bytes extra to make sure we can get 16 byte alignment. We
bufLen =
BufferSizeFromStrideAndHeight(mStride, internalSurfSize.height, 15);
}
if (bufLen == 0) {
mSize.SizeTo(0, 0);
mDataStorage = nullptr;
return;
}
mDataStorage = new uint8_t[bufLen];
if (uintptr_t(mDataStorage) % 16) {
// Our storage does not start at a 16-byte boundary. Make sure mData does!
mData = (uint8_t*)(uintptr_t(mDataStorage) +
(16 - (uintptr_t(mDataStorage) % 16)));
} else {
mData = mDataStorage;
}
mSize = scaleSize;
/* The surface we sample from might not be even sized, if it's not we will
* ignore the last row/column. This means we lose some data but it keeps the
* code very simple. There's also no perfect answer that provides a better
* solution.
*/
IntSize currentSampledSize = mOrigSize;
uint32_t currentSampledStride = mOrigStride;
uint8_t* currentSampledData = mOrigData;
while (verticalDownscales && horizontalDownscales) {
if (currentSampledSize.width % 2) {
currentSampledSize.width -= 1;
}
if (currentSampledSize.height % 2) {
currentSampledSize.height -= 1;
}
HalfImage2D(currentSampledData, currentSampledStride, currentSampledSize,
mData, mStride);
verticalDownscales--;
horizontalDownscales--;
currentSampledSize.width /= 2;
currentSampledSize.height /= 2;
currentSampledData = mData;
currentSampledStride = mStride;
}
while (verticalDownscales) {
if (currentSampledSize.height % 2) {
currentSampledSize.height -= 1;
}
HalfImageVertical(currentSampledData, currentSampledStride,
currentSampledSize, mData, mStride);
verticalDownscales--;
currentSampledSize.height /= 2;
currentSampledData = mData;
currentSampledStride = mStride;
}
while (horizontalDownscales) {
if (currentSampledSize.width % 2) {
currentSampledSize.width -= 1;
}
HalfImageHorizontal(currentSampledData, currentSampledStride,
currentSampledSize, mData, mStride);
horizontalDownscales--;
currentSampledSize.width /= 2;
currentSampledData = mData;
currentSampledStride = mStride;
}
}
void ImageHalfScaler::HalfImage2D(uint8_t* aSource, int32_t aSourceStride,
const IntSize& aSourceSize, uint8_t* aDest,
uint32_t aDestStride) {
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
HalfImage2D_SSE2(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
} else
#endif
{
HalfImage2D_C(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
}
}
void ImageHalfScaler::HalfImageVertical(uint8_t* aSource, int32_t aSourceStride,
const IntSize& aSourceSize,
uint8_t* aDest, uint32_t aDestStride) {
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
HalfImageVertical_SSE2(aSource, aSourceStride, aSourceSize, aDest,
aDestStride);
} else
#endif
{
HalfImageVertical_C(aSource, aSourceStride, aSourceSize, aDest,
aDestStride);
}
}
void ImageHalfScaler::HalfImageHorizontal(uint8_t* aSource,
int32_t aSourceStride,
const IntSize& aSourceSize,
uint8_t* aDest,
uint32_t aDestStride) {
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
HalfImageHorizontal_SSE2(aSource, aSourceStride, aSourceSize, aDest,
aDestStride);
} else
#endif
{
HalfImageHorizontal_C(aSource, aSourceStride, aSourceSize, aDest,
aDestStride);
}
}
void ImageHalfScaler::HalfImage2D_C(uint8_t* aSource, int32_t aSourceStride,
const IntSize& aSourceSize, uint8_t* aDest,
uint32_t aDestStride) {
for (int y = 0; y < aSourceSize.height; y += 2) {
uint32_t* storage = (uint32_t*)(aDest + (y / 2) * aDestStride);
for (int x = 0; x < aSourceSize.width; x += 2) {
uint8_t* upperRow = aSource + (y * aSourceStride + x * 4);
uint8_t* lowerRow = aSource + ((y + 1) * aSourceStride + x * 4);
*storage++ = Avg2x2(*(uint32_t*)upperRow, *((uint32_t*)upperRow + 1),
*(uint32_t*)lowerRow, *((uint32_t*)lowerRow + 1));
}
}
}
void ImageHalfScaler::HalfImageVertical_C(uint8_t* aSource,
int32_t aSourceStride,
const IntSize& aSourceSize,
uint8_t* aDest,
uint32_t aDestStride) {
for (int y = 0; y < aSourceSize.height; y += 2) {
uint32_t* storage = (uint32_t*)(aDest + (y / 2) * aDestStride);
for (int x = 0; x < aSourceSize.width; x++) {
uint32_t* upperRow = (uint32_t*)(aSource + (y * aSourceStride + x * 4));
uint32_t* lowerRow =
(uint32_t*)(aSource + ((y + 1) * aSourceStride + x * 4));
*storage++ = Avg2(*upperRow, *lowerRow);
}
}
}
void ImageHalfScaler::HalfImageHorizontal_C(uint8_t* aSource,
int32_t aSourceStride,
const IntSize& aSourceSize,
uint8_t* aDest,
uint32_t aDestStride) {
for (int y = 0; y < aSourceSize.height; y++) {
uint32_t* storage = (uint32_t*)(aDest + y * aDestStride);
for (int x = 0; x < aSourceSize.width; x += 2) {
uint32_t* pixels = (uint32_t*)(aSource + (y * aSourceStride + x * 4));
*storage++ = Avg2(*pixels, *(pixels + 1));
}
}
}
} // namespace gfx
} // namespace mozilla