Convert drawPaint to drawRRect in simple cases

src/core/SkClipStack.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkAtomics.h"
 #include "SkCanvas.h"
 #include "SkClipStack.h"
@@ skipping 844 matching lines @@
     }
 
     // but is converted to device space here
     temp.offset(SkIntToScalar(offsetX), SkIntToScalar(offsetY));
 
     if (!devBounds->intersect(temp)) {
         devBounds->setEmpty();
     }
 }
 
+bool SkClipStack::isRRect(const SkRect& bounds, SkRRect* rrect, bool* aa) const {
+    // We limit to 5 elements. This means the back element will be bounds checked at most 4 times if
+    // it is an rrect.
+    int cnt = fDeque.count();
+    if (!cnt || cnt > 5) {
+        return false;
+    }
+    const Element* back = static_cast<const Element*>(fDeque.back());
+    if (back->getType() != SkClipStack::Element::kRect_Type &&
+        back->getType() != SkClipStack::Element::kRRect_Type) {
+        return false;
+    }
+    if (back->getOp() == SkRegion::kReplace_Op) {
+        *rrect = back->asRRect();
+        *aa = back->isAA();
+        return true;
+    }
+
+    if (back->getOp() == SkRegion::kIntersect_Op) {
+        SkRect backBounds;

[robertphillips, 2016/08/26 14:00:44]

Why isn't backBounds just back's rect? Shouldn't the quick reject test be if
bounds doesn't contain back's rect?

+        if (!backBounds.intersect(bounds, back->asRRect().rect())) {
+            return false;
+        }
+        if (cnt > 1) {
+            SkDeque::Iter iter(fDeque, SkDeque::Iter::kBack_IterStart);
+            SkAssertResult(static_cast<const Element*>(iter.prev()) == back);
+            while (const Element* prior = (const Element*)iter.prev()) {
+                if ((prior->getOp() != SkRegion::kIntersect_Op &&
+                     prior->getOp() != SkRegion::kReplace_Op) ||
+                    !prior->contains(backBounds)) {
+                    return false;
+                }
+                if (prior->getOp() == SkRegion::kReplace_Op) {
+                    break;
+                }
+            }
+        }
+        *rrect = back->asRRect();
+        *aa = back->isAA();
+        return true;
+    }
+    return false;
+}
+
 int32_t SkClipStack::GetNextGenID() {
     // TODO: handle overflow.
     return sk_atomic_inc(&gGenID);
 }
 
 int32_t SkClipStack::getTopmostGenID() const {
     if (fDeque.empty()) {
         return kWideOpenGenID;
     }
 
@@ skipping 57 matching lines @@
 
 void SkClipStack::dump() const {
     B2TIter iter(*this);
     const Element* e;
     while ((e = iter.next())) {
         e->dump();
         SkDebugf("\n");
     }
 }
 #endif