Fix radii calculation

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 <cmath>
 #include "SkRRect.h"
 #include "SkMatrix.h"
+#include "SkScaleToSides.h"
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkRRect::setRectXY(const SkRect& rect, SkScalar xRad, SkScalar yRad) {
     fRect = rect;
     fRect.sort();
 
     if (fRect.isEmpty() || !fRect.isFinite()) {
         this->setEmpty();
         return;
@@ skipping 82 matching lines @@
     }
 
     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
-}
-
- /**
- *  We need all combinations of predicates to be true to have a "safe" radius value.
- */
-static SkScalar clamp_radius_check_predicates(SkScalar rad, SkScalar min, SkScalar max) {
-    SkASSERT(min < max);
-    if (rad > max - min || min + rad > max || max - rad < min) {
-        rad = SkScalarDecULP(rad);
-    }
-    return rad;
-}
-
 // These parameters intentionally double. Apropos crbug.com/463920, if one of the
 // radii is huge while the other is small, single precision math can completely
 // miss the fact that a scale is required.
 static double compute_min_scale(double rad1, double rad2, double limit, double curMin) {
     if ((rad1 + rad2) > limit) {
         return SkTMin(curMin, limit / (rad1 + rad2));
     }
     return curMin;
 }
 
@@ skipping 39 matching lines @@
     // that to scale down _all_ the radii. This algorithm is from the
     // W3 spec (http://www.w3.org/TR/css3-background/) section 5.5 - Overlapping
     // Curves:
     // "Let f = min(Li/Si), where i is one of { top, right, bottom, left },
     //   Si is the sum of the two corresponding radii of the corners on side i,
     //   and Ltop = Lbottom = the width of the box,
     //   and Lleft = Lright = the height of the box.
     // If f < 1, then all corner radii are reduced by multiplying them by f."
     double scale = 1.0;
 
-    scale = compute_min_scale(fRadii[0].fX, fRadii[1].fX, fRect.width(),  scale);
-    scale = compute_min_scale(fRadii[1].fY, fRadii[2].fY, fRect.height(), scale);
-    scale = compute_min_scale(fRadii[2].fX, fRadii[3].fX, fRect.width(),  scale);
-    scale = compute_min_scale(fRadii[3].fY, fRadii[0].fY, fRect.height(), scale);
+    // The sides of the rectangle may be larger than a float.
+    double width = (double)fRect.fRight - (double)fRect.fLeft;
+    double height = (double)fRect.fBottom - (double)fRect.fTop;
+    scale = compute_min_scale(fRadii[0].fX, fRadii[1].fX, width,  scale);
+    scale = compute_min_scale(fRadii[1].fY, fRadii[2].fY, height, scale);
+    scale = compute_min_scale(fRadii[2].fX, fRadii[3].fX, width,  scale);
+    scale = compute_min_scale(fRadii[3].fY, fRadii[0].fY, height, scale);
 
     if (scale < 1.0) {
-        for (int i = 0; i < 4; ++i) {
-            fRadii[i].fX *= scale;
-            fRadii[i].fY *= scale;
-        }
+        ScaleToSides::AdjustRadii(width,  scale, &fRadii[0].fX, &fRadii[1].fX);
+        ScaleToSides::AdjustRadii(height, scale, &fRadii[1].fY, &fRadii[2].fY);
+        ScaleToSides::AdjustRadii(width,  scale, &fRadii[2].fX, &fRadii[3].fX);
+        ScaleToSides::AdjustRadii(height, scale, &fRadii[3].fY, &fRadii[0].fY);
     }
 
-    // https://bug.skia.org/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()
-    for (int i = 0; i < 4; ++i) {
-        fRadii[i].fX = clamp_radius_check_predicates(fRadii[i].fX, fRect.fLeft, fRect.fRight);
-        fRadii[i].fY = clamp_radius_check_predicates(fRadii[i].fY, fRect.fTop, fRect.fBottom);
-    }
     // At this point we're either oval, simple, or complex (not empty or rect).
     this->computeType();
 
     SkDEBUGCODE(this->validate();)
 }
 
 // This method determines if a point known to be inside the RRect's bounds is
 // inside all the corners.
 bool SkRRect::checkCornerContainment(SkScalar x, SkScalar y) const {
     SkPoint canonicalPt; // (x,y) translated to one of the quadrants
@@ skipping 366 matching lines @@
     }
 
     for (int i = 0; i < 4; ++i) {
         validate_radius_check_predicates(fRadii[i].fX, fRect.fLeft, fRect.fRight);
         validate_radius_check_predicates(fRadii[i].fY, fRect.fTop, fRect.fBottom);
     }
 }
 #endif // SK_DEBUG
 
 ///////////////////////////////////////////////////////////////////////////////