Use for-range loop in pngwrite (vcl)

Change-Id: I957fb399fd1dc630c9a6bdcffe530921eaf66e2d
Reviewed-on: https://gerrit.libreoffice.org/49278Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>

vcl/source/gdi/pngwrite.cxx

@@ -261,24 +261,21 @@ bool PNGWriterImpl::Write(SvStream& rOStm)
     rOStm.WriteUInt32(0x89504e47);
     rOStm.WriteUInt32(0x0d0a1a0a);
 
-    std::vector< vcl::PNGWriter::ChunkData >::iterator aBeg(maChunkSeq.begin());
-    std::vector< vcl::PNGWriter::ChunkData >::iterator aEnd(maChunkSeq.end());
-    while (aBeg != aEnd)
+    for (auto const& chunk : maChunkSeq)
     {
-        sal_uInt32 nType = aBeg->nType;
+        sal_uInt32 nType = chunk.nType;
     #if defined(__LITTLEENDIAN) || defined(OSL_LITENDIAN)
         nType = OSL_SWAPDWORD(nType);
     #endif
         sal_uInt32 nCRC = rtl_crc32(0, &nType, 4);
-        sal_uInt32 nDataSize = aBeg->aData.size();
+        sal_uInt32 nDataSize = chunk.aData.size();
         if (nDataSize)
-            nCRC = rtl_crc32(nCRC, &aBeg->aData[0], nDataSize);
+            nCRC = rtl_crc32(nCRC, &chunk.aData[0], nDataSize);
         rOStm.WriteUInt32(nDataSize);
-        rOStm.WriteUInt32(aBeg->nType);
+        rOStm.WriteUInt32(chunk.nType);
         if (nDataSize)
-            rOStm.WriteBytes(&aBeg->aData[0], nDataSize);
+            rOStm.WriteBytes(&chunk.aData[0], nDataSize);
         rOStm.WriteUInt32(nCRC);
-        ++aBeg;
     }
     rOStm.SetEndian(nOldMode);
     return mbStatus;