Add SkASSERTF.

include/core/SkTypes.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 SkTypes_DEFINED
 #define SkTypes_DEFINED
 
@@ skipping 97 matching lines @@
     #define SkDEBUGF(args)
     #define SkDECLAREPARAM(type, var)
     #define SkPARAM(var)
 
     // unlike SkASSERT, this guy executes its condition in the non-debug build
     #define SkAssertResult(cond)        cond
 #endif
 
 #define SkFAIL(message)                 SK_ALWAYSBREAK(false && message)
 
+// We want to evaluate cond only once, and inside the SkASSERT somewhere so we see its string form.
+// So we use the comma operator to make an SkDebugf that always returns false: we'll evaluate cond,
+// and if it's true the assert passes; if it's false, we'll print the message and the assert fails.
+#define SkASSERTF(cond, fmt, ...)       SkASSERT((cond) || (SkDebugf(fmt"\n", __VA_ARGS__), false))
+
 #ifdef SK_DEVELOPER
     #define SkDEVCODE(code)             code
 #else
     #define SkDEVCODE(code)
 #endif
 
 #ifdef SK_IGNORE_TO_STRING
     #define SK_TO_STRING_NONVIRT()
     #define SK_TO_STRING_VIRT()
     #define SK_TO_STRING_PUREVIRT()
@@ skipping 529 matching lines @@
 private:
     void*       fPtr;
     size_t      fSize;  // can be larger than the requested size (see kReuse)
     uint32_t    fStorage[(kSize + 3) >> 2];
 };
 // Can't guard the constructor because it's a template class.
 
 #endif /* C++ */
 
 #endif