michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "ImageScaling.h"
michael@0: #include "2D.h"
michael@0: #include "DataSurfaceHelpers.h"
michael@0: 
michael@0: #include <math.h>
michael@0: #include <algorithm>
michael@0: 
michael@0: using namespace std;
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace gfx {
michael@0: 
michael@0: inline uint32_t Avg2x2(uint32_t a, uint32_t b, uint32_t c, uint32_t d)
michael@0: {
michael@0:   // Prepare half-adder work
michael@0:   uint32_t sum = a ^ b ^ c;
michael@0:   uint32_t carry = (a & b) | (a & c) | (b & c);
michael@0: 
michael@0:   // Before shifting, mask lower order bits of each byte to avoid underflow.
michael@0:   uint32_t mask = 0xfefefefe;
michael@0: 
michael@0:   // Add d to sum and divide by 2.
michael@0:   sum = (((sum ^ d) & mask) >> 1) + (sum & d);
michael@0: 
michael@0:   // Sum is now shifted into place relative to carry, add them together.
michael@0:   return (((sum ^ carry) & mask) >> 1) + (sum & carry);
michael@0: }
michael@0: 
michael@0: inline uint32_t Avg2(uint32_t a, uint32_t b)
michael@0: {
michael@0:   // Prepare half-adder work
michael@0:   uint32_t sum = a ^ b;
michael@0:   uint32_t carry = (a & b);
michael@0: 
michael@0:   // Before shifting, mask lower order bits of each byte to avoid underflow.
michael@0:   uint32_t mask = 0xfefefefe;
michael@0: 
michael@0:   // Add d to sum and divide by 2.
michael@0:   return ((sum & mask) >> 1) + carry;
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::ScaleForSize(const IntSize &aSize)
michael@0: {
michael@0:   uint32_t horizontalDownscales = 0;
michael@0:   uint32_t verticalDownscales = 0;
michael@0: 
michael@0:   IntSize scaleSize = mOrigSize;
michael@0:   while ((scaleSize.height / 2) > aSize.height) {
michael@0:     verticalDownscales++;
michael@0:     scaleSize.height /= 2;
michael@0:   }
michael@0: 
michael@0:   while ((scaleSize.width / 2) > aSize.width) {
michael@0:     horizontalDownscales++;
michael@0:     scaleSize.width /= 2;
michael@0:   }
michael@0: 
michael@0:   if (scaleSize == mOrigSize) {
michael@0:     return;
michael@0:   }
michael@0: 
michael@0:   IntSize internalSurfSize;
michael@0: 
michael@0:   internalSurfSize.width = max(scaleSize.width, mOrigSize.width / 2);
michael@0:   internalSurfSize.height = max(scaleSize.height, mOrigSize.height / 2);
michael@0: 
michael@0:   mStride = internalSurfSize.width * 4;
michael@0:   if (mStride % 16) {
michael@0:     mStride += 16 - (mStride % 16);
michael@0:   }
michael@0: 
michael@0:   delete [] mDataStorage;
michael@0:   // Allocate 15 bytes extra to make sure we can get 16 byte alignment. We
michael@0:   // should add tools for this, see bug 751696.
michael@0:   size_t bufLen = BufferSizeFromStrideAndHeight(mStride, internalSurfSize.height, 15);
michael@0:   if (bufLen == 0) {
michael@0:     mSize.SizeTo(0, 0);
michael@0:     mDataStorage = nullptr;
michael@0:     return;
michael@0:   }
michael@0:   mDataStorage = new uint8_t[bufLen];
michael@0: 
michael@0:   if (uintptr_t(mDataStorage) % 16) {
michael@0:     // Our storage does not start at a 16-byte boundary. Make sure mData does!
michael@0:     mData = (uint8_t*)(uintptr_t(mDataStorage) +
michael@0:       (16 - (uintptr_t(mDataStorage) % 16)));
michael@0:   } else {
michael@0:     mData = mDataStorage;
michael@0:   }
michael@0: 
michael@0:   mSize = scaleSize;
michael@0: 
michael@0:   /* The surface we sample from might not be even sized, if it's not we will
michael@0:    * ignore the last row/column. This means we lose some data but it keeps the
michael@0:    * code very simple. There's also no perfect answer that provides a better
michael@0:    * solution.
michael@0:    */
michael@0:   IntSize currentSampledSize = mOrigSize;
michael@0:   uint32_t currentSampledStride = mOrigStride;
michael@0:   uint8_t *currentSampledData = mOrigData;
michael@0:   
michael@0:   while (verticalDownscales && horizontalDownscales) {
michael@0:     if (currentSampledSize.width % 2) {
michael@0:       currentSampledSize.width -= 1;
michael@0:     }
michael@0:     if (currentSampledSize.height % 2) {
michael@0:       currentSampledSize.height -= 1;
michael@0:     }
michael@0: 
michael@0:     HalfImage2D(currentSampledData, currentSampledStride, currentSampledSize,
michael@0:                 mData, mStride);
michael@0: 
michael@0:     verticalDownscales--;
michael@0:     horizontalDownscales--;
michael@0:     currentSampledSize.width /= 2;
michael@0:     currentSampledSize.height /= 2;
michael@0:     currentSampledData = mData;
michael@0:     currentSampledStride = mStride;
michael@0:   }
michael@0: 
michael@0:   while (verticalDownscales) {
michael@0:     if (currentSampledSize.height % 2) {
michael@0:       currentSampledSize.height -= 1;
michael@0:     }
michael@0: 
michael@0:     HalfImageVertical(currentSampledData, currentSampledStride, currentSampledSize,
michael@0:                       mData, mStride);
michael@0: 
michael@0:     verticalDownscales--;
michael@0:     currentSampledSize.height /= 2;
michael@0:     currentSampledData = mData;
michael@0:     currentSampledStride = mStride;
michael@0:   }
michael@0: 
michael@0: 
michael@0:   while (horizontalDownscales) {
michael@0:     if (currentSampledSize.width % 2) {
michael@0:       currentSampledSize.width -= 1;
michael@0:     }
michael@0: 
michael@0:     HalfImageHorizontal(currentSampledData, currentSampledStride, currentSampledSize,
michael@0:                         mData, mStride);
michael@0: 
michael@0:     horizontalDownscales--;
michael@0:     currentSampledSize.width /= 2;
michael@0:     currentSampledData = mData;
michael@0:     currentSampledStride = mStride;
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImage2D(uint8_t *aSource, int32_t aSourceStride,
michael@0:                              const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                              uint32_t aDestStride)
michael@0: {
michael@0: #ifdef USE_SSE2
michael@0:   if (Factory::HasSSE2()) {
michael@0:     HalfImage2D_SSE2(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   } else
michael@0: #endif
michael@0:   {
michael@0:     HalfImage2D_C(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImageVertical(uint8_t *aSource, int32_t aSourceStride,
michael@0:                                    const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                                    uint32_t aDestStride)
michael@0: {
michael@0: #ifdef USE_SSE2
michael@0:   if (Factory::HasSSE2()) {
michael@0:     HalfImageVertical_SSE2(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   } else
michael@0: #endif
michael@0:   {
michael@0:     HalfImageVertical_C(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImageHorizontal(uint8_t *aSource, int32_t aSourceStride,
michael@0:                                      const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                                      uint32_t aDestStride)
michael@0: {
michael@0: #ifdef USE_SSE2
michael@0:   if (Factory::HasSSE2()) {
michael@0:     HalfImageHorizontal_SSE2(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   } else
michael@0: #endif
michael@0:   {
michael@0:     HalfImageHorizontal_C(aSource, aSourceStride, aSourceSize, aDest, aDestStride);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImage2D_C(uint8_t *aSource, int32_t aSourceStride,
michael@0:                                const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                                uint32_t aDestStride)
michael@0: {
michael@0:   for (int y = 0; y < aSourceSize.height; y += 2) {
michael@0:     uint32_t *storage = (uint32_t*)(aDest + (y / 2) * aDestStride);
michael@0:     for (int x = 0; x < aSourceSize.width; x += 2) {
michael@0:       uint8_t *upperRow = aSource + (y * aSourceStride + x * 4);
michael@0:       uint8_t *lowerRow = aSource + ((y + 1) * aSourceStride + x * 4);
michael@0: 
michael@0:       *storage++ = Avg2x2(*(uint32_t*)upperRow, *((uint32_t*)upperRow + 1),
michael@0:                           *(uint32_t*)lowerRow, *((uint32_t*)lowerRow + 1));
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImageVertical_C(uint8_t *aSource, int32_t aSourceStride,
michael@0:                                      const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                                      uint32_t aDestStride)
michael@0: {
michael@0:   for (int y = 0; y < aSourceSize.height; y += 2) {
michael@0:     uint32_t *storage = (uint32_t*)(aDest + (y / 2) * aDestStride);
michael@0:     for (int x = 0; x < aSourceSize.width; x++) {
michael@0:       uint32_t *upperRow = (uint32_t*)(aSource + (y * aSourceStride + x * 4));
michael@0:       uint32_t *lowerRow = (uint32_t*)(aSource + ((y + 1) * aSourceStride + x * 4));
michael@0: 
michael@0:       *storage++ = Avg2(*upperRow, *lowerRow);
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: ImageHalfScaler::HalfImageHorizontal_C(uint8_t *aSource, int32_t aSourceStride,
michael@0:                                        const IntSize &aSourceSize, uint8_t *aDest,
michael@0:                                        uint32_t aDestStride)
michael@0: {
michael@0:   for (int y = 0; y < aSourceSize.height; y++) {
michael@0:     uint32_t *storage = (uint32_t*)(aDest + y * aDestStride);
michael@0:     for (int x = 0; x < aSourceSize.width;  x+= 2) {
michael@0:       uint32_t *pixels = (uint32_t*)(aSource + (y * aSourceStride + x * 4));
michael@0: 
michael@0:       *storage++ = Avg2(*pixels, *(pixels + 1));
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: }
michael@0: }