Fix bug with very large round rects with large radii

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 154 matching lines @@
 
     // Proportionally scale down all radii to fit. Find the minimum ratio
     // of a side and the radii on that side (for all four sides) and use
     // 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."

[robertphillips, 2015/03/11 18:13:28]

So, if we don't do this math in doubles the code never realizes there is a
problem.

-    SkScalar scale = SK_Scalar1;
+    double scale = 1.0;
 
-    if (fRadii[0].fX + fRadii[1].fX > rect.width()) {
-        scale = SkMinScalar(scale,
-                            SkScalarDiv(rect.width(), fRadii[0].fX + fRadii[1].fX));
+    if (fRadii[0].fX + ((double)fRadii[1].fX) > rect.width()) {

[reed1, 2015/03/13 14:16:21]

can we use a helper function for these, one that takes doubles?

[robertphillips, 2015/03/13 16:32:35]

Done.

+        scale = SkTMin(scale, rect.width() / (fRadii[0].fX + ((double)fRadii[1].fX)));
     }
-    if (fRadii[1].fY + fRadii[2].fY > rect.height()) {
-        scale = SkMinScalar(scale,
-                            SkScalarDiv(rect.height(), fRadii[1].fY + fRadii[2].fY));
+    if (fRadii[1].fY + ((double)fRadii[2].fY) > rect.height()) {
+        scale = SkTMin(scale, rect.height() / (fRadii[1].fY + ((double)fRadii[2].fY)));
     }
-    if (fRadii[2].fX + fRadii[3].fX > rect.width()) {
-        scale = SkMinScalar(scale,
-                            SkScalarDiv(rect.width(), fRadii[2].fX + fRadii[3].fX));
+    if (fRadii[2].fX + ((double)fRadii[3].fX) > rect.width()) {
+        scale = SkTMin(scale, rect.width() / (fRadii[2].fX + ((double)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 (fRadii[3].fY + ((double)fRadii[0].fY) > rect.height()) {
+        scale = SkTMin(scale, rect.height() / (fRadii[3].fY + ((double)fRadii[0].fY)));
     }
 
-    if (scale < SK_Scalar1) {
+    if (scale < 1.0) {
         for (int i = 0; i < 4; ++i) {
             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
@@ skipping 376 matching lines @@
             SkASSERT(!allRadiiZero && !allRadiiSame && !allCornersSquare);
             SkASSERT(patchesOfNine);
             break;
         case kComplex_Type:
             SkASSERT(!fRect.isEmpty());
             SkASSERT(!allRadiiZero && !allRadiiSame && !allCornersSquare);
             SkASSERT(!patchesOfNine);
             break;
     }
 
     for (int i = 0; i < 4; ++i) {

[robertphillips, 2015/03/11 18:13:28]

This only enforces predicates on individual radii. The failure involves both
radii on a side.

         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
 
 ///////////////////////////////////////////////////////////////////////////////