Revert "Improve quad edges' smoothness in non-AA cases"

This reverts commit d4ed326d6f3704995b0e91292bf2c87e9d36bb14.

Reason for revert: reverting temporarily to get us rolling into Chrome again.

Must be this CL right?
https://storage.googleapis.com/chromium-layout-test-archives/linux_trusty_blink_rel/3364/layout-test-results/results.html

Original change's description:
> Improve quad edges' smoothness in non-AA cases
> 
> Previously, non-AA quad edges only have an accuracy about 1/2 pixel
> (while the AA quad edges have an accuracy about 1/8 pixel).  Now, we
> increase non-AA quad edges' accuracy to 1/8 pixel as well.
> 
> The difference is very significant for rotating non-AA filled circles.
> For example, run `./out/Debug/SampleApp --slide GM:fillcircle` with AA
> turned off (by pressing b).
> 
> The benchmark added reveals that increasing quad accuracy from 1/2 to
> 1/8 doesn't affect the performance significantly. The following is the
> 1/2-accuracy performance versus 1/8-accuracy performance:
> 
> curr/maxrss     loops   min     median  mean    max     stddev  samples
> config  bench
> 7/17  MB        19      2.43µs  2.57µs  2.81µs  10.5µs  22%     16119
> 8888    path_fill_big_nonaacircle
> 7/17  MB        17      1.38µs  1.42µs  1.52µs  13µs    20%     21409
> 8888    path_fill_small_nonaacircle
> 
> curr/maxrss     loops   min     median  mean    max     stddev  samples
> config  bench
> 7/17  MB        71      2.52µs  2.59µs  2.79µs  7.67µs  19%     7557
> 8888    path_fill_big_nonaacircle
> 7/17  MB        64      1.45µs  1.49µs  1.51µs  2.39µs  5%      12704
> 8888    path_fill_small_nonaacircle
> 
> 
> BUG=skia:
> 
> Change-Id: I3482098aeafcc6f2ec9aa3382977c0dc1b650964
> Reviewed-on: https://skia-review.googlesource.com/6699
> Reviewed-by: Mike Reed <reed@google.com>
> Commit-Queue: Yuqian Li <liyuqian@google.com>
> 

TBR=caryclark@google.com,liyuqian@google.com,reed@google.com,djsollen@google.com,bungeman@google.com,reviews@skia.org,fmalita@chromium.org
BUG=skia:
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I5bc4596ab506f6f61ac2da91a07cf51d61114f31
Reviewed-on: https://skia-review.googlesource.com/6829
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>

2 files changed, 3 insertions, 32 deletions

diff --git a/bench/PathBench.cpp b/bench/PathBench.cpp
index 449d30558e..4ca4401163 100644
--- a/bench/PathBench.cpp
+++ b/bench/PathBench.cpp
@@ -173,23 +173,6 @@ private:
     typedef PathBench INHERITED;
 };
 
-class NonAACirclePathBench: public CirclePathBench {
-public:
-    NonAACirclePathBench(Flags flags) : INHERITED(flags) {}
-
-    void appendName(SkString* name) override {
-        name->append("nonaacircle");
-    }
-
-    void setupPaint(SkPaint* paint) override {
-        CirclePathBench::setupPaint(paint);
-        paint->setAntiAlias(false);
-    }
-
-private:
-    typedef CirclePathBench INHERITED;
-};
-
 // Test max speedup of Analytic AA for concave paths
 class AAAConcavePathBench : public PathBench {
 public:
@@ -1107,9 +1090,6 @@ DEF_BENCH( return new CirclePathBench(FLAGS01); )
 DEF_BENCH( return new CirclePathBench(FLAGS10); )
 DEF_BENCH( return new CirclePathBench(FLAGS11); )
 
-DEF_BENCH( return new NonAACirclePathBench(FLAGS00); )
-DEF_BENCH( return new NonAACirclePathBench(FLAGS10); )
-
 DEF_BENCH( return new AAAConcavePathBench(FLAGS00); )
 DEF_BENCH( return new AAAConcavePathBench(FLAGS10); )
 DEF_BENCH( return new AAAConvexPathBench(FLAGS00); )
diff --git a/src/core/SkEdge.cpp b/src/core/SkEdge.cpp
index f8e8d98b5d..216604b551 100644
--- a/src/core/SkEdge.cpp
+++ b/src/core/SkEdge.cpp
@@ -157,22 +157,16 @@ static inline SkFDot6 cheap_distance(SkFDot6 dx, SkFDot6 dy)
     return dx;
 }
 
-static inline int diff_to_shift(SkFDot6 dx, SkFDot6 dy, int shiftAA = 2)
+static inline int diff_to_shift(SkFDot6 dx, SkFDot6 dy)
 {
     // cheap calc of distance from center of p0-p2 to the center of the curve
     SkFDot6 dist = cheap_distance(dx, dy);
 
     // shift down dist (it is currently in dot6)
-    // down by 3 should give us 1/8 pixel accuracy (assuming our dist is accurate...)
+    // down by 5 should give us 1/2 pixel accuracy (assuming our dist is accurate...)
     // this is chosen by heuristic: make it as big as possible (to minimize segments)
     // ... but small enough so that our curves still look smooth
-    // When shift > 0, we're using AA and everything is scaled up so we can
-    // lower the accuracy.
-#ifdef SK_SUPPORT_LEGACY_QUAD_SHIFT
     dist = (dist + (1 << 4)) >> 5;
-#else
-    dist = (dist + (1 << 4)) >> (3 + shiftAA);
-#endif
 
     // each subdivision (shift value) cuts this dist (error) by 1/4
     return (32 - SkCLZ(dist)) >> 1;
@@ -220,10 +214,7 @@ bool SkQuadraticEdge::setQuadraticWithoutUpdate(const SkPoint pts[3], int shift)
     {
         SkFDot6 dx = (SkLeftShift(x1, 1) - x0 - x2) >> 2;
         SkFDot6 dy = (SkLeftShift(y1, 1) - y0 - y2) >> 2;
-        // This is a little confusing:
-        // before this line, shift is the scale up factor for AA;
-        // after this line, shift is the fCurveShift.
-        shift = diff_to_shift(dx, dy, shift);
+        shift = diff_to_shift(dx, dy);
         SkASSERT(shift >= 0);
     }
     // need at least 1 subdivision for our bias trick