Fix bounds of checking if a radii are too long for a side.

BUG=skia:4692,skia:4413
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1617763003

Review URL: https://codereview.chromium.org/1617763003

3 files changed, 46 insertions, 37 deletions

diff --git a/fuzz/FuzzScaleToSides.cpp b/fuzz/FuzzScaleToSides.cpp
index 88a2b920b0..de98562225 100644
--- a/fuzz/FuzzScaleToSides.cpp
+++ b/fuzz/FuzzScaleToSides.cpp
@@ -19,23 +19,22 @@ DEF_FUZZ(ScaleToSides, fuzz) {
     float radius1 = fuzz->nextF(),
           radius2 = fuzz->nextF(),
           width   = fuzz->nextF();
-    SkDebugf("%g %g %g\n", radius1, radius2, width);
 
     if (!std::isfinite(radius1) ||
         !std::isfinite(radius2) ||
-        !std::isfinite(width))
+        !std::isfinite(width)   ||
+        radius1 <= 0.0f         ||
+        radius2 <= 0.0f         ||
+        width <= 0.0f)
     {
         fuzz->signalBoring();
     }
 
-    if (width <= 0.0f) {
-        fuzz->signalBoring();
-    }
-
     double scale = (double)width / ((double)radius1 + (double)radius2);
-    if (scale >= 1.0) {
+    if (scale >= 1.0 || scale <= 0.0) {
         fuzz->signalBoring();
     }
+    SkDebugf("%g %g %g %g\n", radius1, radius2, width, scale);
     ScaleToSides::AdjustRadii(width, scale, &radius1, &radius2);
 
     // TODO(mtklein): add fuzz->keepResult()
diff --git a/src/core/SkScaleToSides.h b/src/core/SkScaleToSides.h
index 77637a3ac2..c3fa172f67 100644
--- a/src/core/SkScaleToSides.h
+++ b/src/core/SkScaleToSides.h
@@ -14,7 +14,7 @@
 
 class ScaleToSides {
 public:
-    // This code assumes that a and b fit in in a float, and therefore the resulting smaller value
+    // This code assumes that a and b fit in a float, and therefore the resulting smaller value
     // of a and b will fit in a float. The side of the rectangle may be larger than a float.
     // Scale must be less than or equal to the ratio limit / (*a + *b).
     // This code assumes that NaN and Inf are never passed in.
@@ -24,8 +24,7 @@ public:
         *a = (float)((double)*a * scale);
         *b = (float)((double)*b * scale);
 
-        // This check is conservative. (double)*a + (double)*b >= (double)(*a + *b)
-        if ((double)*a + (double)*b > limit) {
+        if (*a + *b > limit) {
             float* minRadius = a;
             float* maxRadius = b;
 
@@ -48,14 +47,16 @@ public:
             // reduced by one ULP to be less than limit - newMinRadius.
             // Note: nexttowardf is a c99 call and should be std::nexttoward, but this is not
             // implemented in the ARM compiler.
-            if ((double)newMaxRadius + (double)newMinRadius > limit) {
+            if (newMaxRadius + newMinRadius > limit) {
                 newMaxRadius = nexttowardf(newMaxRadius, 0.0);
             }
             *maxRadius = newMaxRadius;
         }
 
-        SkASSERTF(*a >= 0.0f && *b >= 0.0f, "a: %g, b: %g", *a, *b);
-        SkASSERTF((*a + *b) <= limit, "limit: %g, a: %g, b: %g", limit, *a, *b);
+        SkASSERTF(*a >= 0.0f && *b >= 0.0f, "a: %g, b: %g, limit: %g, scale: %g", *a, *b, limit,
+                  scale);
+        SkASSERTF(*a + *b <= limit, "\nlimit: %.10f, a: %.10f, b: %.10f, scale: %.20f",
+                  limit, *a, *b, scale);
     }
 };
 #endif // ScaleToSides_DEFINED
diff --git a/tests/ScaleToSidesTest.cpp b/tests/ScaleToSidesTest.cpp
index 60e82be529..513f0c98b6 100644
--- a/tests/ScaleToSidesTest.cpp
+++ b/tests/ScaleToSidesTest.cpp
@@ -7,23 +7,27 @@
 
 #include "SkScaleToSides.h"
 
-#include <cfloat>
+#include <algorithm>
 #include "Test.h"
 
 DEF_TEST(ScaleToSides, reporter) {
-    float interestingValues[] = {
-        0.0f,
-        0.5f,
-        1.0f,
-        2.0f,
-        3.0f,
-        33.0f,
-        33554430.0f,
-        33554431.0f,
-        33554464.0f,
-        333333332.0f,
-        333333333.0f,
-        333333334.0f,
+    double interestingValues[] = {
+        // From skp bitbucket
+        111.60000228881836,
+        55.800003051757813,
+        0.99999996581812677920,
+        0.0,
+        0.5,
+        1.0,
+        2.0,
+        3.0,
+        33.0,
+        33554430.0,
+        33554431.0,
+        33554464.0,
+        333333332.0,
+        333333333.0,
+        333333334.0,
         FLT_MAX,
         FLT_EPSILON,
         FLT_MIN
@@ -31,16 +35,21 @@ DEF_TEST(ScaleToSides, reporter) {
 
     int numInterestingValues = (int)SK_ARRAY_COUNT(interestingValues);
 
-    for (int i = 0; i < numInterestingValues; i++) {
-        for (int j = 0; j < numInterestingValues; j++) {
-            for (int k = 0; k < numInterestingValues; k++) {
-                float radius1 = interestingValues[i];
-                float radius2 = interestingValues[j];
-                float width = interestingValues[k];
-                if (width > 0.0f) {
-                    double scale = (double)width / ((double)radius1 + (double)radius2);
-                    if (scale < 1.0) {
-                        ScaleToSides::AdjustRadii(width, scale, &radius1, &radius2);
+    for (int s = 0; s <= numInterestingValues; s++) {
+        for (int i = 0; i < numInterestingValues; i++) {
+            for (int j = 0; j < numInterestingValues; j++) {
+                for (int k = 0; k < numInterestingValues; k++) {
+                    float radius1 = (float)interestingValues[i];
+                    float radius2 = (float)interestingValues[j];
+                    double width = interestingValues[k];
+                    double scale = width / ((double)radius1 + (double)radius2);
+                    if (width > 0.0) {
+                        if (s != 0) {
+                            scale = std::min(scale, interestingValues[s-1]);
+                        }
+                        if (scale < 1.0 && scale > 0.0) {
+                            ScaleToSides::AdjustRadii(width, scale, &radius1, &radius2);
+                        }
                     }
                 }
             }