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-rw-r--r--gfx/2d/ImageScaling.cpp245
1 files changed, 245 insertions, 0 deletions
diff --git a/gfx/2d/ImageScaling.cpp b/gfx/2d/ImageScaling.cpp
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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
+ * 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>
+
+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
+ // should add tools for this, see bug 751696.
+ 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
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