fixed size of buffer returned by wxFormatConverter (it was too large before)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@59939 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/buffer.h

@@ -330,6 +330,17 @@ public:
 
         return true;
     }
+
+    void shrink(size_t len)
+    {
+        wxASSERT_MSG( this->m_data->m_owned, "cannot shrink non-owned buffer" );
+        wxASSERT_MSG( this->m_data->m_ref == 1, "can't shrink shared buffer" );
+
+        wxASSERT( len <= this->length() );
+
+        this->m_data->m_length = len;
+        this->data()[len] = 0;
+    }
 };
 
 WXDLLIMPEXP_TEMPLATE_INSTANCE_BASE( wxCharTypeBuffer<char> )

interface/wx/buffer.h

@@ -200,8 +200,27 @@ public:
 
         Can only be called on buffers that don't share data with another
         buffer (i.e. reference count of the data is 1).
+
+        @see shrink()
      */
     bool extend(size_t len);
+
+    /**
+        Shrinks the buffer to have size @a len and NUL-terminates the string
+        at this length.
+
+        Can only be called on buffers that don't share data with another
+        buffer (i.e. reference count of the data is 1).
+
+        @param len Length to shrink to. Must not be larger than current length.
+
+        @note The string is not reallocated to take less memory.
+
+        @since 2.9.0
+
+        @see extend()
+     */
+    bool shrink(size_t len);
 };
 
 /**

src/common/strvararg.cpp

@@ -152,7 +152,7 @@ public:
         m_nCopied = 0;
     }
 
-    wxCharTypeBuffer<CharType> Convert(const CharType *format)
+    wxScopedCharTypeBuffer<CharType> Convert(const CharType *format)
     {
         // this is reset to NULL if we modify the format string
         m_fmtOrig = format;
@@ -263,12 +263,14 @@ public:
         // format
         if ( m_fmtOrig )
         {
-            return wxCharTypeBuffer<CharType>::CreateNonOwned(m_fmtOrig);
+            return wxScopedCharTypeBuffer<CharType>::CreateNonOwned(m_fmtOrig);
         }
         else
         {
-            // NULL-terminate converted format string:
-            *m_fmtLast = 0;
+            // shrink converted format string to actual size (instead of
+            // over-sized allocation from CopyAllBefore()) and NUL-terminate
+            // it:
+            m_fmt.shrink(m_fmtLast - m_fmt.data());
             return m_fmt;
         }
     }