Add pinned versions of *ToFixed.

include/private/SkFixed.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkFixed_DEFINED
 #define SkFixed_DEFINED
 
 #include "SkScalar.h"
+#include "math.h"
+
 #include "SkTypes.h"
 
 /** \file SkFixed.h
 
     Types and macros for 16.16 fixed point
 */
 
 /** 32 bit signed integer used to represent fractions values with 16 bits to the right of the decimal point
 */
 typedef int32_t             SkFixed;
 #define SK_Fixed1           (1 << 16)
 #define SK_FixedHalf        (1 << 15)
 #define SK_FixedMax         (0x7FFFFFFF)
 #define SK_FixedMin         (-SK_FixedMax)
 #define SK_FixedPI          (0x3243F)
 #define SK_FixedSqrt2       (92682)
 #define SK_FixedTanPIOver8  (0x6A0A)
 #define SK_FixedRoot2Over2  (0xB505)
 
 #define SkFixedToFloat(x)   ((x) * 1.52587890625e-5f)
-#if 1
-    #define SkFloatToFixed(x)   ((SkFixed)((x) * SK_Fixed1))
-#else
-    // pins over/under flows to max/min int32 (slower than just a cast)
-    static inline SkFixed SkFloatToFixed(float x) {
-        int64_t n = x * SK_Fixed1;
-        return (SkFixed)n;
-    }
-#endif
+#define SkFloatToFixed(x)   ((SkFixed)((x) * SK_Fixed1))
+
+// Pins over/under flows to SK_FixedMax/SK_FixedMin (slower than just a cast).
+static inline SkFixed SkFloatPinToFixed(float x) {
+    x *= SK_Fixed1;
+    // Casting float to int outside the range of the target type (int32_t) is undefined behavior.
+    if (x >= SK_FixedMax) return SK_FixedMax;
+    if (x <= SK_FixedMin) return SK_FixedMin;
+    const SkFixed result = static_cast<SkFixed>(x);
+    SkASSERT(truncf(x) == static_cast<float>(result));
+    return result;
+}
 
 #ifdef SK_DEBUG
     static inline SkFixed SkFloatToFixed_Check(float x) {
         int64_t n64 = (int64_t)(x * SK_Fixed1);
         SkFixed n32 = (SkFixed)n64;
         SkASSERT(n64 == n32);
         return n32;
     }
 #else
     #define SkFloatToFixed_Check(x) SkFloatToFixed(x)
 #endif
 
 #define SkFixedToDouble(x)  ((x) * 1.52587890625e-5)
 #define SkDoubleToFixed(x)  ((SkFixed)((x) * SK_Fixed1))
 
+// Pins over/under flows to SK_FixedMax/SK_FixedMin (slower than just a cast).
+static inline SkFixed SkDoublePinToFixed(double x) {
+    x *= SK_Fixed1;
+    // Casting double to int outside the range of the target type (int32_t) is undefined behavior.
+    if (x >= SK_FixedMax) return SK_FixedMax;
+    if (x <= SK_FixedMin) return SK_FixedMin;
+    const SkFixed result = static_cast<SkFixed>(x);
+    SkASSERT(trunc(x) == static_cast<double>(result));
+    return result;
+}
+
 /** Converts an integer to a SkFixed, asserting that the result does not overflow
     a 32 bit signed integer
 */
 #ifdef SK_DEBUG
     inline SkFixed SkIntToFixed(int n)
     {
         SkASSERT(n >= -32768 && n <= 32767);
         // Left shifting a negative value has undefined behavior in C, so we cast to unsigned before
         // shifting.
         return (unsigned)n << 16;
@@ skipping 74 matching lines @@
     #undef SkFloatToFixed
     #define SkFloatToFixed(x)  SkFloatToFixed_arm(x)
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 #if SK_SCALAR_IS_FLOAT
 
 #define SkFixedToScalar(x)          SkFixedToFloat(x)
 #define SkScalarToFixed(x)          SkFloatToFixed(x)
+#define SkScalarPinToFixed(x)       SkFloatPinToFixed(x)
 
 #else   // SK_SCALAR_IS_DOUBLE
 
 #define SkFixedToScalar(x)          SkFixedToDouble(x)
 #define SkScalarToFixed(x)          SkDoubleToFixed(x)
+#define SkScalarPinToFixed(x)       SkDoublePinToFixed(x)
 
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 typedef int64_t SkFixed3232;   // 32.32
 
 #define SkIntToFixed3232(x)       (SkLeftShift((SkFixed3232)(x), 32))
 #define SkFixed3232ToInt(x)       ((int)((x) >> 32))
 #define SkFixedToFixed3232(x)     (SkLeftShift((SkFixed3232)(x), 16))
 #define SkFixed3232ToFixed(x)     ((SkFixed)((x) >> 16))
 #define SkFloatToFixed3232(x)     ((SkFixed3232)((x) * (65536.0f * 65536.0f)))
 
 #define SkScalarToFixed3232(x)    SkFloatToFixed3232(x)
 
 #endif