Fix rrects that are large enough that we lose/gain a bit when we add the radius to a bounds coordin…

src/core/SkRRect.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRRect.h"
 #include "SkMatrix.h"
 
@@ skipping 79 matching lines @@
 
     fRect = rect;
     fRadii[kUpperLeft_Corner].set(leftRad, topRad);
     fRadii[kUpperRight_Corner].set(rightRad, topRad);
     fRadii[kLowerRight_Corner].set(rightRad, bottomRad);
     fRadii[kLowerLeft_Corner].set(leftRad, bottomRad);
 
     SkDEBUGCODE(this->validate();)
 }
 
+/*
+ *  TODO: clean this guy up and possibly add to SkScalar.h
+ */
+static inline SkScalar SkScalarDecULP(SkScalar value) {
+#if SK_SCALAR_IS_FLOAT
+        return SkBits2Float(SkFloat2Bits(value) - 1);
+#else
+    #error "need impl for doubles"
+#endif
+}
+
+static SkScalar clamp_radius_add(SkScalar rad, SkScalar min, SkScalar max) {
+    SkASSERT(rad <= max - min);
+    if (min + rad > max) {
+        rad = SkScalarDecULP(rad);
+    }
+    return rad;
+}
+
+static SkScalar clamp_radius_sub(SkScalar rad, SkScalar min, SkScalar max) {
+    SkASSERT(rad <= max - min);
+    if (max - rad < min) {
+        rad = SkScalarDecULP(rad);
+    }
+    return rad;
+}
 
 void SkRRect::setRectRadii(const SkRect& rect, const SkVector radii[4]) {
     if (rect.isEmpty()) {
         this->setEmpty();
         return;
     }
 
     fRect = rect;
     memcpy(fRadii, radii, sizeof(fRadii));
 
@@ skipping 42 matching lines @@
         scale = SkMinScalar(scale,
                             SkScalarDiv(rect.width(), fRadii[2].fX + fRadii[3].fX));
     }
     if (fRadii[3].fY + fRadii[0].fY > rect.height()) {
         scale = SkMinScalar(scale,
                             SkScalarDiv(rect.height(), fRadii[3].fY + fRadii[0].fY));
     }
 
     if (scale < SK_Scalar1) {
         for (int i = 0; i < 4; ++i) {
-            fRadii[i].fX = SkScalarMul(fRadii[i].fX, scale);
-            fRadii[i].fY = SkScalarMul(fRadii[i].fY, scale);
+            fRadii[i].fX *= scale;
+            fRadii[i].fY *= scale;
         }
     }
 
+    // skbug.com/3239 -- its possible that we can hit the following inconsistency:
+    //     rad == bounds.bottom - bounds.top
+    //     bounds.bottom - radius < bounds.top
+    //     YIKES
+    // We need to detect and "fix" this now, otherwise we can have the following wackiness:
+    //     path.addRRect(rrect);
+    //     rrect.rect() != path.getBounds()
+    fRadii[0].fX = clamp_radius_add(fRadii[0].fX, rect.fLeft, rect.fRight);
+    fRadii[0].fY = clamp_radius_add(fRadii[0].fY, rect.fTop, rect.fBottom);
+    fRadii[1].fX = clamp_radius_sub(fRadii[1].fX, rect.fLeft, rect.fRight);
+    fRadii[1].fY = clamp_radius_add(fRadii[1].fY, rect.fTop, rect.fBottom);
+    fRadii[2].fX = clamp_radius_sub(fRadii[2].fX, rect.fLeft, rect.fRight);
+    fRadii[2].fY = clamp_radius_sub(fRadii[2].fY, rect.fTop, rect.fBottom);
+    fRadii[3].fX = clamp_radius_add(fRadii[3].fX, rect.fLeft, rect.fRight);
+    fRadii[3].fY = clamp_radius_sub(fRadii[3].fY, rect.fTop, rect.fBottom);
+
     // At this point we're either oval, simple, or complex (not empty or rect)
     // but we lazily resolve the type to avoid the work if the information
     // isn't required.
     fType = (SkRRect::Type) kUnknown_Type;
 
     SkDEBUGCODE(this->validate();)
 }
 
 // This method determines if a point known to be inside the RRect's bounds is
 // inside all the corners.
@@ skipping 346 matching lines @@
             SkASSERT(!patchesOfNine);
             break;
         case kUnknown_Type:
             // no limits on this
             break;
     }
 }
 #endif // SK_DEBUG
 
 ///////////////////////////////////////////////////////////////////////////////