Speed up QVersitWriter 2.5x

Avoid round-tripping through Unicode for base-64 encoded data, on
ASCII-compatible codecs

4 files changed, 50 insertions, 4 deletions

diff --git a/src/versit/qvcard21writer.cpp b/src/versit/qvcard21writer.cpp
index 1f987d1611..31bbdd46be 100644
--- a/src/versit/qvcard21writer.cpp
+++ b/src/versit/qvcard21writer.cpp
@@ -67,6 +67,7 @@ void QVCard21Writer::encodeVersitProperty(const QVersitProperty& property)
     QVariant variant(property.variantValue());
 
     QString renderedValue;
+    QByteArray renderedBytes;
     bool useUtf8 = false;
 
     /* Structured values need to have their components backslash-escaped (in vCard 2.1, semicolons
@@ -102,7 +103,10 @@ void QVCard21Writer::encodeVersitProperty(const QVersitProperty& property)
         useUtf8 = encodeVersitValue(parameters, renderedValue);
     } else if (variant.type() == QVariant::ByteArray) {
         parameters.insert(QLatin1String("ENCODING"), QLatin1String("BASE64"));
-        renderedValue = QLatin1String(variant.toByteArray().toBase64().data());
+        if (mCodecIsAsciiCompatible) // optimize by not converting to unicode
+            renderedBytes = variant.toByteArray().toBase64();
+        else
+            renderedValue = QLatin1String(variant.toByteArray().toBase64().data());
     }
 
     // Encode parameters
@@ -121,7 +125,10 @@ void QVCard21Writer::encodeVersitProperty(const QVersitProperty& property)
         // one extra line break after the value are needed in vCard 2.1
         writeCrlf();
         writeString(QLatin1String(" "));
-        writeString(renderedValue, useUtf8);
+        if (renderedBytes.isEmpty())
+            writeString(renderedValue, useUtf8);
+        else
+            writeBytes(renderedBytes);
         writeCrlf();
     }
     writeCrlf();
diff --git a/src/versit/qvcard30writer.cpp b/src/versit/qvcard30writer.cpp
index 97ccc7a7d8..41d38cebdb 100644
--- a/src/versit/qvcard30writer.cpp
+++ b/src/versit/qvcard30writer.cpp
@@ -79,6 +79,7 @@ void QVCard30Writer::encodeVersitProperty(const QVersitProperty& property)
     writeString(QLatin1String(":"));
 
     QString renderedValue;
+    QByteArray renderedBytes;
     if (variant.canConvert<QVersitDocument>()) {
         QVersitDocument embeddedDocument = variant.value<QVersitDocument>();
         QByteArray data;
@@ -122,9 +123,16 @@ void QVCard30Writer::encodeVersitProperty(const QVersitProperty& property)
             }
         }
     } else if (variant.type() == QVariant::ByteArray) {
-        renderedValue = QLatin1String(variant.toByteArray().toBase64().data());
+        if (mCodecIsAsciiCompatible) // optimize by not converting to unicode
+            renderedBytes = variant.toByteArray().toBase64();
+        else
+            renderedValue = QLatin1String(variant.toByteArray().toBase64().data());
     }
-    writeString(renderedValue);
+
+    if (renderedBytes.isEmpty())
+        writeString(renderedValue);
+    else
+        writeBytes(renderedBytes);
     writeCrlf();
 }
 
diff --git a/src/versit/qversitdocumentwriter_p.cpp b/src/versit/qversitdocumentwriter_p.cpp
index 434b7052ef..21866049c7 100644
--- a/src/versit/qversitdocumentwriter_p.cpp
+++ b/src/versit/qversitdocumentwriter_p.cpp
@@ -93,6 +93,11 @@ void QVersitDocumentWriter::setCodec(QTextCodec *codec)
     // Hack so the encoder doesn't output a byte order mark for UTF-8.
     if (mCodec->name() == "UTF-8")
         mEncoder->fromUnicode(QString());
+
+    // UTF-(16|32)(LE|BE) are the only codecs where characters in the base64 range aren't encoded
+    // the same as in ASCII.  For ASCII compatible codecs, we can do some optimizations.
+    mCodecIsAsciiCompatible = !(mCodec->name().startsWith("UTF-16")
+                             || mCodec->name().startsWith("UTF-32"));
 }
 
 /*!
@@ -175,6 +180,31 @@ void QVersitDocumentWriter::encodeGroupsAndName(const QVersitProperty& property)
 
 /*!
   Writes \a value to the device.
+
+  This function tracks how many characters have been written to the line and folds (wraps) the line
+  according to RFC2425.
+  */
+void QVersitDocumentWriter::writeBytes(const QByteArray &value)
+{
+    int spaceRemaining = MAX_LINE_LENGTH - mCurrentLineLength;
+    int charsWritten = 0;
+    while (spaceRemaining < value.length() - charsWritten) {
+        // Write the first "spaceRemaining" characters
+        if (mDevice->write(value.mid(charsWritten, spaceRemaining)) < 0
+               || mDevice->write("\r\n ") < 0)
+            mSuccessful = false;
+        charsWritten += spaceRemaining;
+        spaceRemaining = MAX_LINE_LENGTH - 1; // minus 1 for the space at the front.
+        mCurrentLineLength = 1;
+    }
+
+    if (mDevice->write(value.mid(charsWritten)) < 0)
+        mSuccessful = false;
+    mCurrentLineLength += value.length() - charsWritten;
+}
+
+/*!
+  Writes \a value to the device.
   If \a useUtf8 is true, uses the UTF-8 codec instead of the one set in setCodec().
 
   This function tracks how many characters have been written to the line and folds (wraps) the line
diff --git a/src/versit/qversitdocumentwriter_p.h b/src/versit/qversitdocumentwriter_p.h
index 4c16acd242..ac43ec7242 100644
--- a/src/versit/qversitdocumentwriter_p.h
+++ b/src/versit/qversitdocumentwriter_p.h
@@ -87,6 +87,7 @@ protected:
     QVersitDocument::VersitType mType;
     QIODevice* mDevice;
     QTextCodec* mCodec;
+    bool mCodecIsAsciiCompatible;
     QTextEncoder* mEncoder;
     QTextEncoder* mUtf8Encoder;
     bool mSuccessful;