From 2a679ae8f5b80a337f67783dbc0a447a9f4312c7 Mon Sep 17 00:00:00 2001
From: robertphillips <robertphillips@google.com>
Date: Fri, 13 Mar 2015 09:53:01 -0700
Subject: [PATCH] Fix bug with very large round rects with large radii

BUG=463920

Review URL: https://codereview.chromium.org/998903003
---
 src/core/SkRRect.cpp    | 34 ++++++++++++++++------------------
 tests/RoundRectTest.cpp | 31 ++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/src/core/SkRRect.cpp b/src/core/SkRRect.cpp
index d8b4a20d88..e54256009a 100644
--- a/src/core/SkRRect.cpp
+++ b/src/core/SkRRect.cpp
@@ -128,6 +128,16 @@ static SkScalar clamp_radius_check_predicates(SkScalar rad, SkScalar min, SkScal
     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;
+}
+
 void SkRRect::setRectRadii(const SkRect& rect, const SkVector radii[4]) {
     if (rect.isEmpty() || !rect.isFinite()) {
         this->setEmpty();
@@ -173,26 +183,14 @@ void SkRRect::setRectRadii(const SkRect& rect, const SkVector radii[4]) {
     //   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."
-    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[1].fY + fRadii[2].fY > rect.height()) {
-        scale = SkMinScalar(scale,
-                            SkScalarDiv(rect.height(), fRadii[1].fY + 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[3].fY + fRadii[0].fY > rect.height()) {
-        scale = SkMinScalar(scale,
-                            SkScalarDiv(rect.height(), fRadii[3].fY + fRadii[0].fY));
-    }
+    scale = compute_min_scale(fRadii[0].fX, fRadii[1].fX, rect.width(),  scale);
+    scale = compute_min_scale(fRadii[1].fY, fRadii[2].fY, rect.height(), scale);
+    scale = compute_min_scale(fRadii[2].fX, fRadii[3].fX, rect.width(),  scale);
+    scale = compute_min_scale(fRadii[3].fY, fRadii[0].fY, rect.height(), scale);
 
-    if (scale < SK_Scalar1) {
+    if (scale < 1.0) {
         for (int i = 0; i < 4; ++i) {
             fRadii[i].fX *= scale;
             fRadii[i].fY *= scale;
diff --git a/tests/RoundRectTest.cpp b/tests/RoundRectTest.cpp
index 9920d1013b..8d8f76fbf0 100644
--- a/tests/RoundRectTest.cpp
+++ b/tests/RoundRectTest.cpp
@@ -9,12 +9,29 @@
 #include "SkRRect.h"
 #include "Test.h"
 
-static void test_tricky_radii_crbug_458522(skiatest::Reporter* reporter) {
-    SkRRect rr;
-    const SkRect bounds = { 3709, 3709, 3709 + 7402, 3709 + 29825 };
-    const SkScalar rad = 12814;
-    const SkVector vec[] = { { rad, rad }, { 0, rad }, { rad, rad }, { 0, rad } };
-    rr.setRectRadii(bounds, vec);
+static void test_tricky_radii(skiatest::Reporter* reporter) {
+    {
+        // crbug.com/458522
+        SkRRect rr;
+        const SkRect bounds = { 3709, 3709, 3709 + 7402, 3709 + 29825 };
+        const SkScalar rad = 12814;
+        const SkVector vec[] = { { rad, rad }, { 0, rad }, { rad, rad }, { 0, rad } };
+        rr.setRectRadii(bounds, vec);
+    }
+
+    {
+        // crbug.com//463920
+        SkRect r = SkRect::MakeLTRB(0, 0, 1009, 33554432.0);
+        SkVector radii[4] = {
+            { 13.0f, 8.0f }, { 170.0f, 2.0 }, { 256.0f, 33554432.0 }, { 110.0f, 5.0f }
+        };
+        SkRRect rr;
+        rr.setRectRadii(r, radii);
+
+        REPORTER_ASSERT(reporter, (double) rr.radii(SkRRect::kUpperRight_Corner).fY +
+                                  (double) rr.radii(SkRRect::kLowerRight_Corner).fY <=
+                                  rr.height());
+    }
 }
 
 static void test_empty_crbug_458524(skiatest::Reporter* reporter) {
@@ -660,6 +677,6 @@ DEF_TEST(RoundRect, reporter) {
     test_round_rect_contains_rect(reporter);
     test_round_rect_transform(reporter);
     test_issue_2696(reporter);
-    test_tricky_radii_crbug_458522(reporter);
+    test_tricky_radii(reporter);
     test_empty_crbug_458524(reporter);
 }
-- 
2.34.1