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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCoverageDelta.h"
SkCoverageDeltaList::SkCoverageDeltaList(SkArenaAlloc* alloc, const SkIRect& bounds, bool forceRLE) {
fAlloc = alloc;
fBounds = bounds;
fForceRLE = forceRLE;
int top = bounds.fTop;
int bottom = bounds.fBottom;
// Init the anti-rect to be empty
fAntiRect.fY = bottom;
fAntiRect.fHeight = 0;
fSorted = fAlloc->makeArrayDefault<bool>(bottom - top);
fCounts = fAlloc->makeArrayDefault<int>((bottom - top) * 2);
fMaxCounts = fCounts + bottom - top;
fRows = fAlloc->makeArrayDefault<SkCoverageDelta*>(bottom - top) - top;
fRows[top] = fAlloc->makeArrayDefault<SkCoverageDelta>(INIT_ROW_SIZE * (bottom - top));
memset(fSorted, true, bottom - top);
memset(fCounts, 0, sizeof(int) * (bottom - top));
// Minus top so we can directly use fCounts[y] instead of fCounts[y - fTop].
// Same for fMaxCounts, fRows, and fSorted.
fSorted -= top;
fCounts -= top;
fMaxCounts -= top;
for(int y = top; y < bottom; ++y) {
fMaxCounts[y] = INIT_ROW_SIZE;
}
for(int y = top + 1; y < bottom; ++y) {
fRows[y] = fRows[y - 1] + INIT_ROW_SIZE;
}
}
int SkCoverageDeltaMask::ExpandWidth(int width) {
int result = width + PADDING * 2;
return result + (SIMD_WIDTH - result % SIMD_WIDTH) % SIMD_WIDTH;
}
bool SkCoverageDeltaMask::CanHandle(const SkIRect& bounds) {
// Return early if either width or height is very large because width * height might overflow.
if (bounds.width() >= MAX_MASK_SIZE || bounds.height() >= MAX_MASK_SIZE) {
return false;
}
// Expand width so we don't have to worry about the boundary
return ExpandWidth(bounds.width()) * bounds.height() + PADDING * 2 < MAX_MASK_SIZE;
}
bool SkCoverageDeltaMask::Suitable(const SkIRect& bounds) {
return bounds.width() <= SUITABLE_WIDTH && CanHandle(bounds);
}
SkCoverageDeltaMask::SkCoverageDeltaMask(SkArenaAlloc* alloc, const SkIRect& bounds) {
SkASSERT(CanHandle(bounds));
fBounds = bounds;
// Init the anti-rect to be empty
fAntiRect.fY = fBounds.fBottom;
fAntiRect.fHeight = 0;
fExpandedWidth = ExpandWidth(fBounds.width());
int size = fExpandedWidth * bounds.height() + PADDING * 2;
fDeltaStorage = alloc->makeArray<SkFixed>(size);
fMask = alloc->makeArrayDefault<SkAlpha>(size);
// Add PADDING columns so we may access fDeltas[index(-PADDING, 0)]
// Minus index(fBounds.fLeft, fBounds.fTop) so we can directly access fDeltas[index(x, y)]
fDeltas = fDeltaStorage + PADDING - this->index(fBounds.fLeft, fBounds.fTop);
}
// TODO As this function is so performance-critical (and we're thinking so much about SIMD), use
// SkOpts framework to compile multiple versions of this function so we can choose the best one
// available at runtime.
void SkCoverageDeltaMask::convertCoverageToAlpha(bool isEvenOdd, bool isInverse, bool isConvex) {
SkFixed* deltaRow = &this->delta(fBounds.fLeft, fBounds.fTop);
SkAlpha* maskRow = fMask;
for(int iy = 0; iy < fBounds.height(); ++iy) {
// If we're inside fAntiRect, blit it to the mask and advance to its bottom
if (fAntiRect.fHeight && iy == fAntiRect.fY - fBounds.fTop) {
// Blit the mask
int L = fAntiRect.fX - fBounds.fLeft;
for(int i = 0; i < fAntiRect.fHeight; ++i) {
sk_bzero(maskRow, fBounds.width());
SkAlpha* tMask = maskRow + L;
if (fAntiRect.fLeftAlpha) {
tMask[0] = fAntiRect.fLeftAlpha;
}
memset(tMask + 1, 0xff, fAntiRect.fWidth);
if (fAntiRect.fRightAlpha) {
tMask[fAntiRect.fWidth + 1] = fAntiRect.fRightAlpha;
}
maskRow += fBounds.width();
}
// Advance to the bottom (maskRow is already advanced to the bottom).
deltaRow += fExpandedWidth * fAntiRect.fHeight;
iy += fAntiRect.fHeight - 1; // -1 because we'll ++iy after continue
continue;
}
// Otherwise, cumulate deltas into coverages, and convert them into alphas
SkFixed c[SIMD_WIDTH] = {0}; // prepare SIMD_WIDTH coverages at a time
for(int ix = 0; ix < fExpandedWidth; ix += SIMD_WIDTH) {
// Future todo: is it faster to process SIMD_WIDTH rows at a time so we can use SIMD
// for coverage accumulation?
// Cumulate deltas to get SIMD_WIDTH new coverages
c[0] = c[SIMD_WIDTH - 1] + deltaRow[ix];
for(int j = 1; j < SIMD_WIDTH; ++j) {
c[j] = c[j - 1] + deltaRow[ix + j];
}
using SkNi = SkNx<SIMD_WIDTH, int>;
SkNi cn = SkNi::Load(c);
SkNi an = isConvex ? ConvexCoverageToAlpha(cn, isInverse)
: CoverageToAlpha(cn, isEvenOdd, isInverse);
SkNx_cast<SkAlpha>(an).store(maskRow + ix);
}
// Finally, advance to the next row
deltaRow += fExpandedWidth;
maskRow += fBounds.width();
}
}
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