gfx/2d/ImageScaling.cpp
 author Birunthan Mohanathas Mon, 13 Jul 2015 08:25:42 -0700 changeset 284279 91d6e262b662a0b4e47358665e222d3927337af9 parent 209519 b6e15020d2d79a53d6f60c85129ee3d04ceec89b child 353763 53dc795121e100ca900642f0ba0ce295d69bd903 permissions -rw-r--r--
Bug 1182996 - Fix and add missing namespace comments. rs=ehsan The bulk of this commit was generated by running: run-clang-tidy.py \ -checks='-*,llvm-namespace-comment' \ -header-filter=^/.../mozilla-central/.* \ -fix
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/* -*- 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/. */

#include "ImageScaling.h"
#include "2D.h"
#include "DataSurfaceHelpers.h"

#include <math.h>
#include <algorithm>

using namespace std;

namespace mozilla {
namespace gfx {

inline uint32_t Avg2x2(uint32_t a, uint32_t b, uint32_t c, uint32_t d)
{
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.

// 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)
{
uint32_t sum = a ^ b;
uint32_t carry = (a & b);

// Before shifting, mask lower order bits of each byte to avoid underflow.

// 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;
}

IntSize internalSurfSize;

internalSurfSize.width = max(scaleSize.width, mOrigSize.width / 2);
internalSurfSize.height = max(scaleSize.height, mOrigSize.height / 2);

mStride = internalSurfSize.width * 4;
if (mStride % 16) {
mStride += 16 - (mStride % 16);
}

delete [] mDataStorage;
// Allocate 15 bytes extra to make sure we can get 16 byte alignment. We
// should add tools for this, see bug 751696.
size_t 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,
{
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
} else
#endif
{
}
}

void
ImageHalfScaler::HalfImageVertical(uint8_t *aSource, int32_t aSourceStride,
{
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
} else
#endif
{
}
}

void
ImageHalfScaler::HalfImageHorizontal(uint8_t *aSource, int32_t aSourceStride,
{
#ifdef USE_SSE2
if (Factory::HasSSE2()) {
} else
#endif
{
}
}

void
ImageHalfScaler::HalfImage2D_C(uint8_t *aSource, int32_t aSourceStride,
{
for (int y = 0; y < aSourceSize.height; y += 2) {
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,
{
for (int y = 0; y < aSourceSize.height; y += 2) {
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,
{
for (int y = 0; y < aSourceSize.height; y++) {