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

src/core/SkString.cpp

 
 /*
  * 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.
  */
 
 
 #include "SkAtomics.h"
@@ skipping 17 matching lines @@
 
 #define ARGS_TO_BUFFER(format, buffer, size, written)      \
     do {                                                   \
         va_list args;                                      \
         va_start(args, format);                            \
         written = VSNPRINTF(buffer, size, format, args);   \
         SkASSERT(written >= 0 && written < SkToInt(size)); \
         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[]) {
     SkASSERT(string);
     SkASSERT(suffixStr);
     size_t  strLen = strlen(string);
     size_t  suffixLen = strlen(suffixStr);
     return  strLen >= suffixLen &&
             !strncmp(string + strLen - suffixLen, suffixStr, suffixLen);
 }
@@ skipping 482 matching lines @@
     this->insert(offset, p, buffer + sizeof(buffer) - p);
 }
 
 void SkString::insertScalar(size_t offset, SkScalar value) {
     char    buffer[SkStrAppendScalar_MaxSize];
     char*   stop = SkStrAppendScalar(buffer, value);
     this->insert(offset, buffer, stop - buffer);
 }
 
 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[], ...) {
     char    buffer[kBufferSize];
     int length;
     ARGS_TO_BUFFER(format, buffer, kBufferSize, length);
 
     this->append(buffer, length);
 }
 
@@ skipping 53 matching lines @@
 
 void SkString::swap(SkString& other) {
     this->validate();
     other.validate();
 
     SkTSwap<Rec*>(fRec, other.fRec);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+// 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) {
     const char* end = str + strlen(str);
     while (str != end) {
         // Find a token.
         const size_t len = strcspn(str, delimiters);
         out->push_back().set(str, len);
         str += len;
         // Skip any delimiters.
         str += strspn(str, delimiters);
     }
 }
 
 #undef VSNPRINTF
 #undef SNPRINTF