[composer] Fix incorrect calculation of frame thickness for labels

Previously entire frame width was considered when calculating
the margin for the label item. Only half the frame width should be
used, since half is drawn outside the item rect.

Author: nyalldawson

src/core/composer/qgscomposerlabel.cpp

@@ -92,7 +92,7 @@ void QgsComposerLabel::paint( QPainter* painter, const QStyleOptionGraphicsItem*
   //antialiasing on
   painter->setRenderHint( QPainter::Antialiasing, true );
 
-  double penWidth = hasFrame() ? pen().widthF() : 0;
+  double penWidth = hasFrame() ? ( pen().widthF() / 2.0 ) : 0;
   QRectF painterRect( penWidth + mMargin, penWidth + mMargin, rect().width() - 2 * penWidth - 2 * mMargin, rect().height() - 2 * penWidth - 2 * mMargin );
 
   QString textToDraw = displayText();
@@ -286,7 +286,7 @@ void QgsComposerLabel::adjustSizeToText()
   double textWidth = QgsComposerUtils::textWidthMM( mFont, displayText() );
   double fontHeight = QgsComposerUtils::fontHeightMM( mFont );
 
-  double penWidth = hasFrame() ? pen().widthF() : 0;
+  double penWidth = hasFrame() ? ( pen().widthF() / 2.0 ) : 0;
 
   double width = textWidth + 2 * mMargin + 2 * penWidth + 1;
   double height = fontHeight + 2 * mMargin + 2 * penWidth;