check bounds of each cubic segment against clip

src/core/SkEdgeClipper.cpp

 
 /*
  * Copyright 2009 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkEdgeClipper.h"
@@ skipping 340 matching lines @@
         tmp[3].fX = clip.fRight;
         clamp_le(tmp[2].fX, clip.fRight);
 
         this->appendCubic(tmp, reverse);
         this->appendVLine(clip.fRight, tmp[3].fY, tmp[6].fY, reverse);
     } else {    // wholly inside the clip
         this->appendCubic(pts, reverse);
     }
 }
 
+static bool quick_reject_in_y(const SkPoint pts[4], const SkRect& clip) {

[mtklein, 2015/12/17 14:58:15]

Just for fun, let's compare speed with

  SkScalar min = SkTMin(SkTMin(pts[0].fY, pts[1].fY), SkTMin(pts[2].fY,
pts[3].fY));
  SkScalar max = SkTMax(SkTMax(pts[0].fY, pts[1].fY), SkTMax(pts[2].fY,
pts[3].fY));
  return min > clip.bottom() || max < clip.top();

?

If it's roughly the same speed on your desktop, I'd go with that.  Hopping back
and forth between scalar and vector code isn't cheap on ARM, nor is allTrue().

+    Sk4s ys(pts[0].fY, pts[1].fY, pts[2].fY, pts[3].fY);
+    Sk4s t(clip.top());
+    Sk4s b(clip.bottom());
+
+    return (ys < t).allTrue() || (ys > b).allTrue();
+}
+
 bool SkEdgeClipper::clipCubic(const SkPoint srcPts[4], const SkRect& clip) {
     fCurrPoint = fPoints;
     fCurrVerb = fVerbs;
 
-    SkRect  bounds;
-    bounds.set(srcPts, 4);
-
-    if (!quick_reject(bounds, clip)) {
+    if (!quick_reject_in_y(srcPts, clip)) {
         SkPoint monoY[10];
         int countY = SkChopCubicAtYExtrema(srcPts, monoY);
         for (int y = 0; y <= countY; y++) {
             SkPoint monoX[10];
             int countX = SkChopCubicAtXExtrema(&monoY[y * 3], monoX);
             for (int x = 0; x <= countX; x++) {
                 this->clipMonoCubic(&monoX[x * 3], clip);
                 SkASSERT(fCurrVerb - fVerbs < kMaxVerbs);
                 SkASSERT(fCurrPoint - fPoints <= kMaxPoints);
             }
@@ skipping 99 matching lines @@
         assert_monotonic(&pts[0].fY, count);
     }
 }
 
 void sk_assert_monotonic_x(const SkPoint pts[], int count) {
     if (count > 1) {
         assert_monotonic(&pts[0].fX, count);
     }
 }
 #endif