SkStringPrintf and SkString::printf now are no longer limted by a static buffer

src/core/SkString.cpp

Index: src/core/SkString.cpp
diff --git a/src/core/SkString.cpp b/src/core/SkString.cpp
index d93f662da3d8bc0a80ca96903752bbcc3977ba1e..99b14162f4d8d2744c0ad3e5761fc8ef327118eb 100644
--- a/src/core/SkString.cpp
+++ b/src/core/SkString.cpp
@@ -35,6 +35,48 @@ static const size_t kBufferSize = 1024;
         va_end(args);                                      \
     } while (0)
 
+static SkString v_skstring_printf(const char* format, va_list args) {
+#ifdef SK_BUILD_FOR_WIN
+    va_list args_copy;
+    va_copy(args_copy, args);
+    char buffer[1024];
+    int length = _vsnprintf_s(buffer, sizeof(buffer), _TRUNCATE, format, args_copy);
+    va_end(args_copy);
+    if (length >= 0 && length < (int)sizeof(buffer)) {
+        return SkString(buffer, length);
+    }
+    va_copy(args_copy, args);
+    length = _vscprintf(format, args);
+    va_end(args_copy);
+
+    SkString formattedOutput((size_t)length);
+    SkDEBUGCODE(int check = ) _vsnprintf_s(formattedOutput.writable_str(),
+                                           length + 1, _TRUNCATE, format, args);
+    SkASSERT(check == length);
+    SkASSERT(formattedOutput[length] == '\0');
+    return skstd::move(formattedOutput);
+#else  // C99/C++11 standard vsnprintf
+    // TODO: When all compilers support this, remove windows-specific code.
+    va_list args_copy;
+    va_copy(args_copy, args);
+    char buffer[1024];
+    int length = vsnprintf(buffer, sizeof(buffer), format, args);
+    va_end(args_copy);
+    if (length < 0) {
+        return SkString();
+    }
+    if (length < (int)sizeof(buffer)) {
+        return SkString(buffer, length);
+    }
+    SkString formattedOutput((size_t)length);
+    SkDEBUGCODE(int check = )
+            vsnprintf(formattedOutput.writable_str(), length + 1, format, args);
+    SkASSERT(check == length);
+    SkASSERT(formattedOutput[length] == '\0');
+    return skstd::move(formattedOutput);
+#endif
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkStrEndsWith(const char string[], const char suffixStr[]) {
@@ -537,11 +579,10 @@ void SkString::insertScalar(size_t offset, SkScalar value) {
 }
 
 void SkString::printf(const char format[], ...) {
-    char    buffer[kBufferSize];
-    int length;
-    ARGS_TO_BUFFER(format, buffer, kBufferSize, length);
-
-    this->set(buffer, length);
+    va_list args;
+    va_start(args, format);
+    *this = v_skstring_printf(format, args);
+    va_end(args);
 }
 
 void SkString::appendf(const char format[], ...) {
@@ -615,13 +656,14 @@ void SkString::swap(SkString& other) {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+// Improvement on SkStringPrintf to allow for arbitrarily long output.

[tomhudson, 2015/10/12 20:21:01]

This feels like a comment that belongs in the commit note, rather than the
source file. How can SkStringPrintf be an improvement on SkStringPrintf? Rather,
the change you're making is an improvement, right?

[hal.canary, 2015/10/12 21:38:24]

Done.

+// TODO: replace SkStringPrintf.
 SkString SkStringPrintf(const char* format, ...) {
-    SkString formattedOutput;
-    char buffer[kBufferSize];
-    SK_UNUSED int length;
-    ARGS_TO_BUFFER(format, buffer, kBufferSize, length);
-    formattedOutput.set(buffer);
-    return formattedOutput;
+    va_list args;
+    va_start(args, format);
+    SkString formattedOutput(v_skstring_printf(format, args));
+    va_end(args);
+    return skstd::move(formattedOutput);
 }
 
 void SkStrSplit(const char* str, const char* delimiters, SkTArray<SkString>* out) {