AuroraMiddleware/skia2
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Remove accumulative snapping error

Browse Source 
BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4769

Change-Id: Ie70bdc280c680c82f3b8a186466bf3a0835a9107
Reviewed-on: https://skia-review.googlesource.com/4769
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
This commit is contained in:
Yuqian Li 2016-11-14 11:51:41 -05:00 committed by Skia Commit-Bot
parent efa62e1d5b
commit 0038b7feaa
2 changed files with 16 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
gm/aaa.cpp
View File

@ -61,6 +61,20 @@ protected:
path.lineTo(SkBits2Float(0x429b9d5c), SkBits2Float(0x4367a041)); // 77.8073f, 231.626f
path.close();
canvas->drawPath(path, p);
// The following path reveals a subtle SkAnalyticQuadraticEdge::updateQuadratic bug:
// we should not use any snapped y for the intermediate values whose error may accumulate;
// snapping should only be allowed once before updateLine.
path.reset();
path.moveTo(SkBits2Float(0x434ba71e), SkBits2Float(0x438a06d0)); // 203.653f, 276.053f
path.lineTo(SkBits2Float(0x43492a74), SkBits2Float(0x4396d70d)); // 201.166f, 301.68f
// 200.921f, 304.207f, 196.939f, 303.82f, 0.707107f
path.conicTo(SkBits2Float(0x4348ebaf), SkBits2Float(0x43981a75),
SkBits2Float(0x4344f079), SkBits2Float(0x4397e900), SkBits2Float(0x3f3504f3));
path.close();
// Manually setting convexity is required. Otherwise, this path will be considered concave.
path.setConvexity(SkPath::kConvex_Convexity);
canvas->drawPath(path, p);
}
private:

4
src/core/SkAnalyticEdge.cpp
View File

@ -135,13 +135,13 @@ bool SkAnalyticQuadraticEdge::updateQuadratic() {
if (--count > 0)
{
newx = oldx + (dx >> shift);
newy = snapY(oldy + (dy >> shift));
newy = oldy + (dy >> shift);
slope = dy >> 10 > 0 ? quickSkFDot6Div(dx >> 10, dy >> 10) : SK_MaxS32;
if (SkAbs32(dy) >= SK_Fixed1 * 2) { // only snap when dy is large enough
newSnappedY = SkTMin<SkFixed>(fQEdge.fQLastY, SkFixedRoundToFixed(newy));
newSnappedX = newx + SkFixedMul_lowprec(slope, newSnappedY - newy);
} else {
newSnappedY = newy;
newSnappedY = SkTMin(fQEdge.fQLastY, snapY(newy));
newSnappedX = newx;
}
dx += fQEdge.fQDDx;